Synergistic effects between silver nanoparticles and antibiotics and the mechanisms involved

Controlling the formation of fast-growing silver nanocubes in non-polar solvents

The key to the most efficient nanostructures is a deep understanding and control of all factors influencing the reaction mechanism. To realize the full potential of a synthesis of Ag nanocubes in a non-polar solvent mixture, the factors that determine the results are thoroughly investigated. In this hot-injection approach, an Ag precursor reacts with a Cl precursor to form AgCl and multiply twinned (MT) Ag nanoparticles. The AgCl is then reduced to single crystalline Ag nanoparticles while the MT nanoparticles are oxidized. As a result, the single crystals grow into nanocubes. Previously unidentified factors like the catalytic influence of Fe(III) ions and the in situ formation of HCl, which leads to an undefined chloride content, are revealed. A high reproducibility is achieved by controlling the amount of Fe(III) ions and adding a stable Cl source. Thoroughly investigating and combining the effects of chloride concentration with temperature and oxidative etching allows for adjusting the edge length of the nanocubes in the range of 40 to 100 nm and improving their uniformity. These findings lead to a robust protocol for producing non-polar silver nanocubes with sharp edges, low polydispersity, tunable size, and thus tunable optical properties in a short reaction time.

Silver Nanoparticles (AgNPs) from Lysinibacillus sp. Culture Broths: Antibacterial Activity, Mechanism Insights, and Synergy with Classical Antibiotics

Antibiotic-resistant bacteria pose problems for infection prevention and treatment, so developing new procedures or substances against infection is mandatory. Silver nanomaterials are among the more promising antibacterial agents. Herein, we describe the biogenic synthesis of silver nanoparticles (AgNPs) using culture broths from an undescribed species of Lysinibacillus. Culture broths with or without NaCl and from the exponential and stationary growth phases produced four AgNP types. Nanoparticles' shapes were quasi-spherical, with core sizes of 7.5-14.7 nm and hydrodynamic diameters of 48.5-80.2 nm. All the AgNPs contained Ag0 crystals and some AgCl ones. Moreover, their coronas presented different proportions of carbohydrates, proteins, and aliphatic compounds. The AgNPs were good antibacterial agents against six bacterial species, three Gram-positive and three Gram-negative, with MICs of 0.3-9.0 µg/mL. Their activity was higher against the Gram-negative bacteria and particularly against Pseudomonas aeruginosa. These AgNPs acted synergistically with several of the fifteen tested antibiotics. Interestingly, AgNP combinations with some of these inhibited the growth of antibiotic-resistant bacteria, as in the case of S. epidermidis for streptomycin and S. aureus for colistin. The ROS production by E. coli and S. aureus when treated with most AgNPs suggested different mechanisms for bacterial killing depending on the AgNP.

Harnessing Silver Nanoclusters to Combat Staphylococcus aureus in the Era of Antibiotic Resistance

Background/Objectives: In the race to develop new antibiotics to combat multidrug-resistant bacteria, particularly the ESKAPE pathogens which pose a significant threat to public health, silver nanoclusters (AgNCs) have emerged as a promising alternative. This article focuses on the potential of novel silver nanoclusters as an antimicrobial agent against Staphylococcus aureus, a high-priority pathogen known for its ability to cause persistent nosocomial infections and develop protective biofilms. Methods: In this study, we successfully synthesized AgNCs at pH 7 using an eco-friendly photoreduction method with poly acrylic acid (PAA) and poly methacrylic acid (PMAA) as stabilizers. This methodology produced fluorescent AgNCs, demonstrating their stability in aqueous solutions for at least three months and highlighting the effectiveness of PAA and PMAA as stabilizing agents. The AgNCs were incubated with S. aureus suspension, and the antimicrobial capability at different concentrations and times of incubation were determined. Also, the AgNCs hemocompatibility was studied by exposing the clusters to rat blood cells. Results: The in vitro assays revealed that AgNCs capping with PAA or PMAA has antimicrobial activity in low doses (the determination of minimum inhibitory concentration (MIC): 0.2 µg/mL, and the determination of minimum bactericidal concentration (MBC): 2 µg/mL) and without cytotoxicity (hemolysis less than 10%) to rat blood cells until 1 µg/mL. In the presence of both AgNCs (5 µg/mL), bacterial growth was completely inhibited within just 3 h. Conclusions: The findings of this study highlight the potential of silver nanoclusters as effective antimicrobial agents against S. aureus. Their stability, low toxicity, and rapid bactericidal activity make them promising candidates for further development in antimicrobial applications.

Fluoridated silver nanocomposites for caries management: an in-vitro assessment of the cytological and antibacterial profiles

BACKGROUND

Silver nanoparticles (AgNPs) have antibacterial properties with potential applications in managing dental caries. Functionalization with fluoride may further enhance AgNPs' antibacterial efficacy. This study evaluated the impact of fluoridated AgNPs coated with various surface moieties on their safety profile and antibacterial effects against cariogenic bacteria as a potential anti-cariogenic treatment.

METHODS

AgNP synthesis followed citrate and gallic acid reduction methods with polyethylene glycol (PEG) and polyvinylpyrrolidone coating. Functionalizing AgNPs with sodium fluoride (NaF) proceeded. Testing the safety of synthesized compounds was done on human gingival fibroblasts and oral epithelial cells. Meanwhile, minimum inhibitory concentration (MIC) determination against Streptococcus mutans was executed to verify antibacterial activity.

RESULTS

Gallic-reduced AgNPs revealed higher yielding capacity than citrate-AgNPs. Cytologically, PEGylation reinforced citrate-AgNPs stability and improved IC50 range up to ∼ 4.2 × 1016 µg/mL and 64.3 µg/mL on fibroblastic and epithelial lineages. PEGylated AgNPs counteracted the cytotoxicity of free NaF with antagonistic combinational effect of NaF@PEG gallic-AgNPs on gingival fibroblasts. Microbiologically, AgNPs recorded an enhanced antimicrobial activity of ∼ 5.3 ± 2.3 µg/mL averaged MIC against Streptococcus mutans. Furthermore, fluoridation of PEG gallic-AgNPs depicted an additive antimicrobial propensity.

CONCLUSIONS

This dual action nanoplatform successfully integrates fluoride and silver components, reducing fluoride concentrations to safety range while maximizing silver's antibacterial properties. Engineered NaF@PEGylated nanosilver formulation represents promising anti-cariogenic strategy that optimizes therapeutic efficacy while maintaining biological safety.

Harnessing bioactive nanocurcumin and curcumin nanocomposites to combat microbial pathogens: a comprehensive review

The alarming rise in bacterial infections including those caused by multidrug-resistant pathogens has garnered the attention of the scientific community, compelling them to explore as novel and effective alternatives to combat these infections. Moreover, the emerging viruses such as Influenza A virus subtype H1N1 (A/H1N1), Middle East Respiratory Syndrome Coronavirus (MERS-CoV), Ebolavirus, recent coronavirus (SARS-CoV-2), etc. also has a significant impact all over the world. Therefore, the management of all such infections without any side effects is one of the most important challenges for the scientific community. Hence, the development of novel and effective antimicrobial agents is a need of the hour. In this context, Curcuma longa, commonly known as turmeric, has been used as traditional medicine for centuries to manage and treat such infections. Its bioactive constituent, curcumin has garnered significant attention in medicine due to its multifunctional bioactivities. Apart from antimicrobial properties, it also possesses potent antioxidant and anti-inflammatory activities. However, available reports suggest that its low solubility, stability, and biocompatibility limit its use. Moreover, on the other hand, it has been reported that these limitations associated with the use of curcumin can be resolved by transforming it into its nano-form, specifically curcumin nanoparticles. Recent advancements have brought curcumin nanoparticles into the spotlight, showcasing superior properties and a broad spectrum of antimicrobial applications. In this review, we have mainly focused on antimicrobial potential of curcumin and nanocurcumin, mechanisms underpinning their antimicrobial actions. Moreover, other aspects of toxicity and safety guidelines for nano-based products have been also discussed.

Silver Nanoparticles as Antimicrobial Agents in Veterinary Medicine: Current Applications and Future Perspectives

Silver nanoparticles (AgNPs) have gained significant attention in veterinary medicine due to their antimicrobial properties and potential therapeutic applications. Silver has long been recognized for its ability to combat a wide range of pathogens, and when engineered at the nanoscale, silver's surface area and reactivity are greatly enhanced, making it highly effective against bacteria, viruses, and fungi. This narrative review aimed to summarize the evidence on the antimicrobial properties of AgNPs and their current and potential clinical applications in veterinary medicine. The antimicrobial action of AgNPs involves several mechanisms, including, among others, the release of silver ions, disruption of cell membranes and envelopes, induction of oxidative stress, inhibition of pathogens' replication, and DNA damage. Their size, shape, surface charge, and concentration influence their efficacy against bacteria, viruses, and fungi. As a result, the use of AgNPs has been explored in animals for infection prevention and treatment in some areas, such as wound care, coating of surgical implants, animal reproduction, and airway infections. They have also shown promise in preventing biofilm formation, a major challenge in treating chronic bacterial infections. Additionally, AgNPs have been studied for their potential use in animal feed as a supplement to enhance animal health and growth. Research suggested that AgNPs could stimulate immune responses and improve the gut microbiota of livestock, potentially reducing the need for antibiotics in animal husbandry. Despite their promising applications, further research is necessary to fully understand the safety, efficacy, and long-term effects of AgNPs on animals, humans, and the environment.

Response Surface D-Optimal Design for Optimizing Fortimicins Production by Micromonospora olivasterospora and New Synergistic Fortimicin-A-Antibiotic Combinations

Fortimicins (FTMs) are fortamine-containing aminoglycoside antibiotics (AGAs) produced by M. olivasterospora DSM 43868 with excellent bactericidal activities against a wide range of Enterobacteriaceae and synergistic activity against multidrug-resistant (MDR) pathogens. Fortimicin-A (FTM-A), the most active member of FTMs, has the lowest susceptibility to inactivation by the aminoglycoside modifying enzymes (AMEs). Therefore, this study aimed to evaluate the antibacterial activity of FTM-A alone or in combination with other antibiotics against 18 non-clonal clinically relevant MDR Gram-positive and Gram-negative pathogens. This study also aimed to statistically optimize various environmental factors affecting its production using the response surface D-optimal design. Results showed that FTM-A/meropenem combination showed the highest synergistic bactericidal activity (61.1%) followed by its combination with cefotaxime and cefepime (38.8% each). However, FTM-A/gentamicin and FTM-A/doxycycline combinations showed mostly additive effects in 66.6% and 50% of the tested isolates, respectively. For FTM-A production optimization, maximum specific activity (µg/mg) to cell growth was achieved using aminoglycoside production medium followed by yeast extract-malt extract and M65 production medium. A D-optimal quadratic model consisting of 27 different media composition variations was used to predict an optimal composition for FTM-A production and verified experimentally. Lab verification of the model was carried out using HPLC analysis, resulting in a 10.5-fold increase in their production compared to the un-optimized conditions. The model revealed that the initial pH, incubation temperature, and incubation time significantly affected FTMs production (P-value < 0.05), however, the tested range of calcium carbonate 2-7 gL-1 and agitation rate (100-300 rpm) showed no significant effect (P-value > 0.05). In conclusion, the D-optimal design resulted in an effective model and optimized FTMs production on the shake flask level. FTM-A combinations with meropenem, cefotaxime, cefepime, and gentamicin showed mostly synergistic/additive effects and are advised for clinical evaluation.

Synergistic Antibacterial Effect of ZnO Nanoparticles and Antibiotics against Multidrug-resistant Biofilm Bacteria

BACKGROUND

The misuse of antibiotics leads to a global increase in antibiotic resistance. Therefore, it is imperative to search for alternative compounds to conventional antibiotics. ZnO nanoparticles (Zn NP) are one of these alternatives because they are an effective option to overcome biofilm bacterial cells and a novel way to overcome multidrug resistance in bacteria. The current research study aims to characterize the efficacy of ZnO nanoparticles alone and in combination with other antibacterial drugs against bacterial biofilms.

METHODS

ZnO NPs were prepared by co-precipitation method, and their anti-biofilm and antibacterial activities alone or combined with four types of broad-spectrum antibacterial (Norfloxacin, Colistin, Doxycycline, and Ampicillin) were evaluated against E. coli and S. aureus bacterial strains. Finally, the cytotoxicity and the hemolytic activity were evaluated.

RESULTS

ZnO NPs were prepared, and results showed that their size was around 10 nm with a spherical shape and a zeta potential of -21.9. In addition, ZnO NPs were found to have a strong antibacterial effect against Gram-positive and Gram-negative microorganisms, with a minimum inhibitory concentration (MIC) of 62.5 and 125 μg/mL, respectively. Additionally, they could eradicate biofilmforming microorganisms at a concentration of 125 μg/m. ZnO NPs were found to be non-toxic to erythrocyte cells. Still, some toxicity was observed for Vero cells at effective concentration ranges needed to inhibit bacterial growth and eradicate biofilm-forming organisms. When combined with different antibacterial, ZnO NP demonstrated synergistic and additive effects with colistin, and the MIC and MBEC of the combination decreased significantly to 0.976 μg/mL against planktonic and biofilm strains of MDR Gram-positive bacteria, resulting in significantly reduced toxicity.

CONCLUSION

The findings of this study encourage the development of alternative therapies with high efficacy and low toxicity. ZnO nanoparticles have demonstrated promising results in overcoming multi-drug resistant bacteria and biofilms, and their combination with colistin has shown a significant reduction in toxicity. Further studies are needed to investigate the potential of ZnO nanoparticles as a viable alternative to conventional antibiotics.

Nanotechnology: An avenue for combating fish parasites in aquaculture system

The intensification of aquaculture in recent years has led to the rise of infectious fish diseases caused by bacteria, viruses, and parasites. Parasitic diseases, in particular, are widespread and have significant economic impacts globally. Protozoan parasites like Ichthyophthirius multifiliis and Trichodina sp., myxozoans (cnidarians), monogeneans like Dactylogyrus sp. and Gyrodactylus sp., and crustacean parasites like Argulus sp. and Lernaea cyprinacea primarily cause these diseases. Despite advancements and new technologies aimed at understanding and treating these diseases, parasites remain a major health challenge in aquaculture. Traditional antiparasitic agents face limitations, including drug resistance and negative effects on non-target organisms. Recently, nanotechnology has emerged as a novel approach in aquaculture medicine, enabling the development of effective nanoparticles against pathogenic microbes. Silver nanoparticles (AgNPs) are particularly notable for their strong antimicrobial and antiparasitic properties due to their broad mechanisms of action. Although Argulus is a highly destructive crustacean parasite that financially burdens fish farmers, applying nanoparticles to manage this infection in aquaculture is still underexplored. Therefore, this review explores recent efforts to combat parasitic diseases with AgNPs and investigates their potential parasiticidal mechanisms of action, proposing them as a novel tool that could improve the management and control of argulosis diseases. The article underscores the benefits and challenges of this technology, emphasizing its significance in fostering improved health management for sustainable aquaculture.

Recent Advances in the Development of Metal/Metal Oxide Nanoparticle and Antibiotic Conjugates (MNP-Antibiotics) to Address Antibiotic Resistance: Review and Perspective

As per the World Health Organization (WHO), antimicrobial resistance (AMR) is a natural phenomenon whereby microbes develop or acquire genes that render them resistant. The rapid emergence and spread of this phenomenon can be attributed to human activity specifically, the improper and excessive use of antimicrobials for the treatment, prevention, or control of infections in humans, animals, and plants. As a result of this factor, many antibiotics have reduced effectiveness against microbes or may not work fully. Thus, there is a pressing need for the development of new antimicrobial agents in order to counteract antimicrobial resistance. Metallic nanoparticles (MNPs) are well known for their broad antimicrobial properties. Consequently, the use of MNPs with current antibiotics holds significant implications. MNPs, including silver nanoparticles (AgNPS), zinc oxide nanoparticles (ZnONPs), copper nanoparticles (CuNPs), and gold nanoparticles (AuNPs), have been extensively studied in conjunction with antibiotics. However, their mechanism of action is still not completely understood. The interaction between these MNPs and antibiotics can be either synergistic, additive, or antagonistic. The synergistic effect is crucial as it represents the desired outcome that researchers aim for and can be advantageous for the advancement of new antimicrobial agents. This article provides a concise and academic description of the recent advancements in MNP and antibiotic conjugates, including their mechanism of action. It also highlights their possible use in the biomedical field and major challenges associated with the use of MNP-antibiotic conjugates in clinical practice.

Bacterial Apoptosis-Like Death through Accumulation of Reactive Oxygen Species by Quercetin in Escherichia coli

The antimicrobial activity of the natural compounds from plant and food have well discovered since the interest on the beneficial effect of the natural compounds was risen. Quercetin, a flavonoid derived from vegetables, including onions, red leaf lettuces and cherries has been studied for diverse biological characteristics as anti-cancer and anti-microbial activities. The aim of current study is to investigate the specific antibacterial modes of action of quercetin against Escherichia coli. Quercetin decreased the E. coli cell viability and induced the severe damages (oxidative stress, DNA fragmentation) leading to cell death. Reactive oxygen species (ROS) generation was observed during the process, which we confirmed that oxidative stress was the key action of antibacterial activity of quercetin exerting its influence potently. Based on the results of Annexin V and Caspace FITC-VAD-FMK assay, the oxidative damage in E. coli has led to the bacterial apoptosis-like death in E. coli. To sum up, the contribution of ROS generation exerts crucial impact in antibacterial activity of quercetin.

Eradication of Klebsiella pneumoniae pulmonary infection by silver oxytetracycline nano-structure

Targeted bactericidal nanosystems hold significant promise to improve the efficacy of existing antimicrobials for treatment of severe bacterial infections by minimizing the side effects and lowering the risk of antibiotic resistance development. In this work, Silver Oxytetracycline Nano-structure (Ag-OTC-Ns) was developed for selective and effective eradication of Klebsiella pneumoniae pulmonary infection. Ag-OTC-Ns were prepared by simple homogenization-ultrasonication method and were characterized by DLS, Zeta potential, TEM and FT-IR. The antimicrobial activity of Ag-OTC-Ns was evaluated in vitro using broth micro-dilution technique and time-kill methods. Our study showed that MICs of AgNO3, OTC, AgNPs and Ag-OTC-Ns were 100, 100, 50 and 6.25 µg/ml, respectively. Ag-OTC-Ns demonstrated higher bactericidal efficacy against the targeted Klebsiella pneumoniae at 12.5 µg/ml compared to the free Oxytetracycline, AgNO3 and AgNPs. In vivo results confirmed that, Ag-OTC-Ns could significantly eradicate K. pneumoniae from mice lung in compare with free Oxytetracycline, AgNO3 and AgNPs. In addition, Ag-OTC-Ns could effectually diminish the inflammatory biomarkers levels of Interferon Gamma and IL-12, and as a result it could effectively lower lung damage in K. pneumoniae infected mice. Ag-OTC-Ns has no significant toxicity on tested mice along the experimental period, there was no sign of behavioral abnormality in the surviving mice indicating that the Ag-OTC-Ns is safe at the used concentration. Furthermore, capability of 5 kGy Gamma ray to sterilize Ag-OTC-Ns solution without affecting it stability was proven.

Combinations of Cannabinoids with Silver Salts or Silver Nanoparticles for Synergistic Antibiotic Effects against Methicillin-Resistant Staphylococcus aureus

Silver has been shown to improve the antibiotic effects of other drugs against both Gram- positive and -negative bacteria. In this study, we investigated the antibiotic potential of cannabidiol (CBD), cannabichromene (CBC) and cannabigerol (CBG) and their acidic counterparts (CBDA, CBCA, CBGA) against Gram-positive bacteria and further explored the additive or synergistic effects of silver nitrate or silver nanoparticles using 96-well plate growth assays and viability (CFUs- colony-forming units). All six cannabinoids had strong antibiotic effects against MRSA with minimal inhibitory concentrations (MICs) of 2 mg/L for CBG, CBD and CBCA; 4 mg/L for CBGA; and 8 mg/L for CBC and CBDA. Using 96-well checkerboard assays, CBC, CBG and CBGA showed full or partial synergy with silver nitrate; CBC, CBDA and CBGA were fully synergistic with silver nanoparticles against MRSA. Using CFU assays, combinations of CBC, CBGA and CBG with either silver nitrate or silver nanoparticles, all at half or quarter MICs, demonstrated strong, time-dependent inhibition of bacterial growth (silver nitrate) and bactericidal effects (silver nanoparticles). These data will lead to further investigation into possible biomedical applications of specific cannabinoids in combination with silver salts or nanoparticles against drug-resistant Gram-positive bacteria.

Novel silver nanoparticle-antibiotic combinations as promising antibacterial and anti-biofilm candidates against multiple-antibiotic resistant ESKAPE microorganisms

HYPOTHESIS

The emergence of Multiple Antibiotic Resistance (MAR) in ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) pathogens is a global challenge to public health. The inherent antimicrobial nature of silver nanoparticles (AgNPs) makes them promising antimicrobial candidates against antibiotic-resistant pathogens. This study explores the combination of AgNPs with antibiotics (SACs) to create new antimicrobial agents effective against MAR ESKAPE microorganisms.

METHODS

AgNPs were synthesized using Streptococcus pneumoniae ATCC 49619 and characterized for structure and surface properties. The SACs were tested against ESKAPE microorganisms using growth kinetics and time-kill curve methods. The effect of SACs on bacterial biofilms and the disruption of cell membranes was determined. The in-vitro cytotoxicity effect of the AgNPs was also studied.

FINDINGS

The synthesized AgNPs (spherical, 7.37±4.55 nm diameter) were antimicrobial against MAR ESKAPE microorganisms. The SACs showed synergy with multiple conventional antibiotics, reducing their antibacterial concentrations up to 32-fold. Growth kinetics and time-kill studies confirmed the growth retardation effect and bactericidal activity of SACs. Mechanistic studies suggested that these biofilm-eradicating SACs probably resulted in the loss of bacterial cell membrane integrity, leading to leakage of the cytoplasmic content. The AgNPs were highly cytotoxic against skin melanoma cells but non-cytotoxic to normal Vero cells.

Synergistic Antibacterial Effects of Gallate Containing Compounds with Silver Nanoparticles in Gallate Crossed Linked PVA Hydrogel Films

Currently available silver-based antiseptic wound dressings have limited patient effectiveness. There exists a need for wound dressings that behave as comfortable degradable hydrogels with a strong antibiotic potential. The objectives of this project were to investigate the combined use of gallates (either epi gallo catechin gallate (EGCG), Tannic acid, or Quercetin) as both PVA crosslinking agents and as potential synergistic antibiotics in combination with silver nanoparticles. Crosslinking was assessed gravimetrically, silver and gallate release was measured using inductively coupled plasma and HPLC methods, respectively. Synergy was measured using 96-well plate FICI methods and in-gel antibacterial effects were measured using planktonic CFU assays. All gallates crosslinked PVA with optimal extended swelling obtained using EGCG or Quercetin at 14% loadings (100 mg in 500 mg PVA with glycerol). All three gallates were synergistic in combination with silver nanoparticles against both gram-positive and -negative bacteria. In PVA hydrogel films, silver nanoparticles with EGCG or Quercetin more effectively inhibited bacterial growth in CFU counts over 24 h as compared to films containing single agents. These biocompatible natural-product antibiotics, EGCG or Quercetin, may play a dual role of providing stable PVA hydrogel films and a powerful synergistic antibiotic effect in combination with silver nanoparticles.

Unveiling biological activities of biosynthesized starch/silver-selenium nanocomposite using Cladosporium cladosporioides CBS 174.62

BACKGROUND AND OBJECTIVES

Microbial cells capability to tolerate the effect of various antimicrobial classes represent a major worldwide health concern. The flexible and multi-components nanocomposites have enhanced physicochemical characters with several improved properties. Thus, different biological activities of biosynthesized starch/silver-selenium nanocomposite (St/Ag-Se NC) were assessed.

METHODOLOGY

The St/Ag-Se NC was biosynthesized using Cladosporium cladosporioides CBS 174.62 (C. cladosporioides) strain. The shape and average particle size were investigated using scanning electron microscope (SEM) and high-resolution transmission electron microscope (HR-TEM), respectively. On the other hand, the St/Ag-Se NC effect on two cancer cell lines and red blood cells (RBCs) was evaluated and its hydrogen peroxide (H2O2) scavenging effect was assessed. Moreover, its effects on various microbial species in both planktonic and biofilm growth forms were examined.

RESULTS

The St/Ag-Se NC was successfully biosynthesized with oval and spherical shape and a mean particle diameter of 67.87 nm as confirmed by the HR-TEM analysis. St/Ag-Se NC showed promising anticancer activity toward human colorectal carcinoma (HCT-116) and human breast cancer (MCF-7) cell lines where IC50 were 21.37 and 19.98 µg/ml, respectively. Similarly, little effect on RBCs was observed with low nanocomposite concentration. As well, the highest nanocomposite H2O2 scavenging activity (42.84%) was recorded at a concentration of 2 mg/ml. Additionally, Staphylococcus epidermidis (S. epidermidis) ATCC 12,228 and Candida albicans (C. albicans) ATCC 10,231 were the highly affected bacterial and fungal strains with minimum inhibitory concentrations (MICs) of 18.75 and 50 µg/ml, respectively. Moreover, the noticeable effect of St/Ag-Se NC on microbial biofilm was concentration dependent. A high biofilm suppression percentage, 87.5% and 68.05%, were recorded with S. epidermidis and Staphylococcus aureus (S. aureus) when exposed to 1 mg/ml and 0.5 mg/ml, respectively.

CONCLUSION

The biosynthesized St/Ag-Se NC showed excellent antioxidant activity, haemocompatibility, and anti-proliferative effect at low concentrations. Also, it exhibited promising antimicrobial and antibiofilm activities.

Nanoparticle-based platforms for targeted drug delivery to the pulmonary system as therapeutics to curb cystic fibrosis: A review

Cystic fibrosis (CF) is a genetic disorder of the respiratory system caused by mutation of the Cystic Fibrosis Trans-Membrane Conductance Regulator (CFTR) gene that affects a huge number of people worldwide. It results in difficulty breathing due to a large accumulation of mucus in the respiratory tract, resulting in serious bacterial infections, and subsequent death. Traditional drug-based treatments face hindered penetration at the site of action due to the thick mucus layer. Nanotechnology offers possibilities for developing advanced and effective treatment platforms by focusing on drugs that can penetrate the dense mucus layer, fighting against the underlying bacterial infections, and targeting the genetic cause of the disease. In this review, current nanoparticle-mediated drug delivery platforms for CF, challenges in therapeutics, and future prospects have been highlighted. The effectiveness of the different types of nano-based systems conjugated with various drugs to combat the symptoms and the challenges of treating CF are brought into focus. The toxic effects of these nano-medicines and the various factors that are responsible for their effectiveness are also highlighted.

Synergistic Effect of Silver Nanoparticles with Antibiotics for Eradication of Pathogenic Biofilms

BACKGROUND

The increase in nosocomial multidrug resistance and biofilm-forming bacterial infections led to the search for new alternative antimicrobial strategies other than traditional antibiotics. Silver nanoparticles (AgNP) could be a viable treatment due to their wide range of functions, rapid lethality, and minimal resistance potential. The primary aim of this study is to prepare silver nanoparticles and explore their antibacterial activity against biofilms.

METHODS

AgNPs with specific physicochemical properties such as size, shape, and surface chemistry were prepared using a chemical reduction technique, and then characterized by DLS, SEM, and FTIR. The activity of AgNPs was tested alone and in combination with some antibiotics against MDR Gram-negative and Gram-positive planktonic bacterial cells and their biofilms. Finally, mammalian cell cytotoxicity and hemolytic activity were tested using VERO and human erythrocytes.

RESULTS

The findings of this study illustrate the success of the chemical reduction method in preparing AgNPs. Results showed that AgNPs have MIC values against planktonic organisms ranging from 0.0625 to 0.125 mg/mL, with the greatest potency against gram-negative bacteria. It also effectively destroyed biofilm-forming cells, with minimal biofilm eradication concentrations (MBEC) ranging from 0.125 to 0.25 mg/ml. AgNPs also had lower toxicity profiles for the MTT test when compared to hemolysis to erythrocytes. Synergistic effect was found between AgNPs and certain antibiotics, where the MIC was dramatically reduced, down to less than 0.00195 mg/ml in some cases.

CONCLUSION

The present findings encourage the development of alternative therapies with high efficacy and low toxicity.

Bibliometric insights into the most influential papers on antibiotic adjuvants: a comprehensive analysis

Background: The utilization of antibiotic adjuvants presents a promising strategy for addressing bacterial resistance. Recently, the development of antibiotic adjuvants has attracted considerable attention from researchers in academia and industry. This study aimed to identify the most influential publications on antibiotic adjuvants and elucidate the hotspots and research trends in this field. Method: Original articles and reviews related to antibiotic adjuvants were retrieved from the Web of Science Core Collection database. The top 100 highly cited publications were selected and the visual analyses of publication outputs, countries, institutions, authors, journals, and keywords were conducted using Excel, VOSviewer, or CtieSpace software tools. Results: The top 100 cited publications concerning antibiotic adjuvants spanned the years 1977-2020, with citation counts ranging from 174 to 2,735. These publications encompassed 49 original articles and 51 reviews. The journal "Antimicrobial Agents and Chemotherapy" accounted for the highest number of publications (12%). The top 100 cited publications emanated from 39 countries, with the United States leading in production. Institutions in Canada and the United States exhibited the most substantial contributions to these highly cited publications. A total of 526 authors participated in these studies, with Robert E.W. Hancock, Laura J. V. Piddock, Xian-Zhi Li, Hiroshi Nikaido, and Olga Lomovskaya emerging as the most frequently nominated authors. The most common keywords included "E. coli", "P. aeruginosa", "S. aureus", "in-vitro activity", "antimicrobial peptide", "efflux pump inhibitor" "efflux pump", "MexAB-OprM" and "mechanism". These keywords underscored the hotspots of bacterial resistance mechanisms and the development of novel antibiotic adjuvants. Conclusion: Through the bibliometric analysis, this study identified the top 100 highly cited publications on antibiotic adjuvants. Moreover, the findings offered a comprehensive understanding of the characteristics and frontiers in this field.

Combatting resistance: Understanding multi-drug resistant pathogens in intensive care units

The escalating misuse and excessive utilization of antibiotics have led to the widespread dissemination of drug-resistant bacteria, posing a significant global healthcare crisis. Of particular concern is the increasing prevalence of multi-drug resistant (MDR) opportunistic pathogens in Intensive Care Units (ICUs), which presents a severe threat to public health and contributes to substantial morbidity and mortality. Among them, MDR ESKAPE pathogens account for the vast majority of these opportunistic pathogens. This comprehensive review provides a meticulous analysis of the current prevalence landscape of MDR opportunistic pathogens in ICUs, especially in ESKAPE pathogens, illuminating their resistance mechanisms against commonly employed first-line antibiotics, including polymyxins, carbapenems, and tigecycline. Furthermore, this review explores innovative strategies aimed at preventing and controlling the emergence and spread of resistance. By emphasizing the urgent need for robust measures to combat nosocomial infections caused by MDR opportunistic pathogens in ICUs, this study serves as an invaluable reference for future investigations in the field of antibiotic resistance.

The Green Synthesis of Silver Nanoparticles from Avena fatua Extract: Antifungal Activity against Fusarium oxysporum f.sp. lycopersici

Using plant extracts as eco-friendly reducing and stabilizing agents for the synthesis of nanoparticles has gained significant attention in recent years. The current study explores the green synthesis of silver nanoparticles (AgNPs) using the Avena fatua extract and evaluates their antifungal activity against Fusarium oxysporum f.sp. lycopersici (Fol), a fungal plant pathogen. A green and sustainable approach was adopted to synthesize silver nanoparticles before these nanoparticles were employed for anti-fungal activity. The primary indication that AgNPs had formed was performed using UV-vis spectroscopy, where a strong peak at 425 nm indicated the effective formation of these nanoparticles. The indication of important functional groups acting as reducing and stabilizing agents was conducted using the FTIR study. Additionally, morphological studies were executed via SEM and AFM, which assisted with more effectively analyzing AgNPs. Crystalline behavior and size were estimated using powder XRD, and it was found that AgNPs were highly crystalline, and their size ranged from 5 to 25 nm. Synthesized AgNPs exhibited significant antifungal activity against Fol at a concentration of 40 ppm. Furthermore, the inhibitory index confirmed a positive correlation between increasing AgNPs concentration and exposure duration. This study suggests that the combined phytochemical mycotoxic effect of the plant extract and the smaller size of synthesized AgNPs were responsible for the highest penetrating power to inhibit Fol growth. Moreover, this study highlights the potential of using plant extracts as reducing and capping agents for the green synthesis of AgNPs with antifungal properties. The study concludes that A. fatua extract can synthesize antifungal AgNPs as a sustainable approach with robust antifungal efficacy against Fol, underscoring their promising potential for integration into plant protection strategies.

Inorganic Nanoparticles: Tools to Emphasize the Janus Face of Amphotericin B

Amphotericin B is the oldest antifungal molecule which is still currently widely used in clinical practice, in particular for the treatment of invasive diseases, even though it is not devoid of side effects (particularly nephrotoxicity). Recently, its redox properties (i.e., both prooxidant and antioxidant) have been highlighted in the literature as mechanisms involved in both its activity and its toxicity. Interestingly, similar properties can be described for inorganic nanoparticles. In the first part of the present review, the redox properties of Amphotericin B and inorganic nanoparticles are discussed. Then, in the second part, inorganic nanoparticles as carriers of the drug are described. A special emphasis is given to their combined redox properties acting either as a prooxidant or as an antioxidant and their connection to the activity against pathogens (i.e., fungi, parasites, and yeasts) and to their toxicity. In a majority of the published studies, inorganic nanoparticles carrying Amphotericin B are described as having a synergistic activity directly related to the rupture of the redox homeostasis of the pathogen. Due to the unique properties of inorganic nanoparticles (e.g., magnetism, intrinsic anti-infectious properties, stimuli-triggered responses, etc.), these nanomaterials may represent a new generation of medicine that can synergistically enhance the antimicrobial properties of Amphotericin B.

Antimicrobial Peptide Synergies for Fighting Infectious Diseases

Antimicrobial peptides (AMPs) are essential elements of thehost defense system. Characterized by heterogenous structures and broad-spectrumaction, they are promising candidates for combating multidrug resistance. Thecombined use of AMPs with other antimicrobial agents provides a new arsenal ofdrugs with synergistic action, thereby overcoming the drawback of monotherapiesduring infections. AMPs kill microbes via pore formation, thus inhibitingintracellular functions. This mechanism of action by AMPs is an advantage overantibiotics as it hinders the development of drug resistance. The synergisticeffect of AMPs will allow the repurposing of conventional antimicrobials andenhance their clinical outcomes, reduce toxicity, and, most significantly,prevent the development of resistance. In this review, various synergies ofAMPs with antimicrobials and miscellaneous agents are discussed. The effect ofstructural diversity and chemical modification on AMP properties is firstaddressed and then different combinations that can lead to synergistic action,whether this combination is between AMPs and antimicrobials, or AMPs andmiscellaneous compounds, are attended. This review can serve as guidance whenredesigning and repurposing the use of AMPs in combination with other antimicrobialagents for enhanced clinical outcomes.

The Antibacterial Effectiveness of Citrullus lanatus-Mediated Stannous Nanoparticles on Streptococcus mutans

Introduction Dental caries is a prevalent oral health issue caused by the colonization of Streptococcus mutans in the oral cavity. Citrullus lanatus, commonly known as watermelon, is rich in bioactive compounds that possess antibacterial potential. In this study, we aimed to synthesize stannous chloride (SnCl2) nanoparticles (NPs) mediated by Citrullus lanatus extract and investigate their antibacterial effectiveness against Streptococcus mutans. Materials and method Stannous nanoparticles (SnNPs) synthesized by the green method were achieved by using the watermelon extract. Dilute stannous chloride solution was obtained by adding 0.45 g of stannous (Sn) chloride (Cl) powder to 60 mL of water, which was subjected to an orbital shaker with the watermelon extract. The nanoparticles obtained were subjected to characterization using antimicrobial testing, Fourier transform infrared (FTIR) spectroscopy, energy-dispersive X-ray (EDAX) analysis, and scanning electron microscopy (SEM). Agar well diffusion method was used against specific strains of S. aureus, S. mutans, and Escherichia coli. Results The novel nanoparticles demonstrated promising antibacterial activity against S. mutans providing 10 mm of inhibitory action. Conclusion Due to its abundance of naturally occurring bioactive chemicals and improved efficacy against S. mutans, watermelon extract can be utilized to create stannous nanoparticles as opposed to the use of toxic chemicals. They can also be employed as oral administration systems.

Effects of Sulforaphene on the Cariogenic Properties of Streptococcus Mutans In Vitro and Dental Caries Development In Vivo

Sulforaphene (SFE) is a common nutritional supplement with antibacterial, anti-cancer, and anti-inflammatory effects. However, the effects of SFE on the cariogenicity of Streptococcus mutans and dental caries have not been reported. The objectives of this study were to investigate the caries-controlling potential of SFE. The effects of SFE on S. mutans were investigated using the broth microdilution method, crystal violet staining, SEM observation, acid tolerance assays, lactic acid quantification, and polysaccharide measurements. A rat caries model was established to evaluate the caries-controlling effects and biocompatibility of SFE in vivo. SFE inhibited S. mutans growth and biofilm formation. Furthermore, SFE restrained the cariogenic properties of S. mutans, including its acid production, acid tolerance, and extracellular polysaccharide production, without affecting the bacterial viability at sub-inhibitory levels. In the rat caries model, SFE significantly arrested the onset and development of dental caries. Moreover, no visible hemolytic phenomenon or cytotoxicity was detected in the SFE groups. After four weeks of SFE treatment, all rats remained in apparent good health with no significant differences in weight gain; their hemogram and biochemical parameters were normal; no pathological changes were observed in the oral mucosa, liver, or kidneys. In conclusion, SFE was safe and inhibited the development of caries effectively.

Insights into the Synergistic Antibacterial Activity of Silver Nitrate with Potassium Tellurite against Pseudomonas aeruginosa

The constant, ever-increasing antibiotic resistance crisis leads to the announcement of "urgent, novel antibiotics needed" by the World Health Organization. Our previous works showed a promising synergistic antibacterial activity of silver nitrate with potassium tellurite out of thousands of other metal/metalloid-based antibacterial combinations. The silver-tellurite combined treatment not only is more effective than common antibiotics but also prevents bacterial recovery, decreases the risk of future resistance chance, and decreases the effective concentrations. We demonstrate that the silver-tellurite combination is effective against clinical isolates. Further, this study was conducted to address knowledge gaps in the available data on the antibacterial mechanism of both silver and tellurite, as well as to give insight into how the mixture provides synergism as a combination. Here, we defined the differentially expressed gene profile of Pseudomonas aeruginosa under silver, tellurite, and silver-tellurite combination stress using an RNA sequencing approach to examine the global transcriptional changes in the challenged cultures grown in simulated wound fluid. The study was complemented with metabolomics and biochemistry assays. Both metal ions mainly affected four cellular processes, including sulfur homeostasis, reactive oxygen species response, energy pathways, and the bacterial cell membrane (for silver). Using a Caenorhabditis elegans animal model we showed silver-tellurite has reduced toxicity over individual metal/metalloid salts and provides increased antioxidant properties to the host. This work demonstrates that the addition of tellurite would improve the efficacy of silver in biomedical applications. IMPORTANCE Metals and/or metalloids could represent antimicrobial alternatives for industrial and clinical applications (e.g., surface coatings, livestock, and topical infection control) because of their great properties, such as good stability and long half-life. Silver is the most common antimicrobial metal, but resistance prevalence is high, and it can be toxic to the host above a certain concentration. We found that a silver-tellurite composition has antibacterial synergistic effect and that the combination is beneficial to the host. So, the efficacy and application of silver could increase by adding tellurite in the recommended concentration(s). We used different methods to evaluate the mechanism for how this combination can be so incredibly synergistic, leading to efficacy against antibiotic- and silver-resistant isolates. Our two main findings are that (i) both silver and tellurite mostly target the same pathways and (ii) the coapplication of silver with tellurite tends not to target new pathways but targets the same pathways with an amplified change.

Nanosilver: An Old Antibacterial Agent with Great Promise in the Fight against Antibiotic Resistance

Antibiotic resistance in bacteria is a major problem worldwide that costs 55 billion USD annually for extended hospitalization, resource utilization, and additional treatment expenditures in the United States. This review examines the roles and forms of silver (e.g., bulk Ag, silver salts (AgNO3), and colloidal Ag) from antiquity to the present, and its eventual incorporation as silver nanoparticles (AgNPs) in numerous antibacterial consumer products and biomedical applications. The AgNP fabrication methods, physicochemical properties, and antibacterial mechanisms in Gram-positive and Gram-negative bacterial models are covered. The emphasis is on the problematic ESKAPE pathogens and the antibiotic-resistant pathogens of the greatest human health concern according to the World Health Organization. This review delineates the differences between each bacterial model, the role of the physicochemical properties of AgNPs in the interaction with pathogens, and the subsequent damage of AgNPs and Ag+ released by AgNPs on structural cellular components. In closing, the processes of antibiotic resistance attainment and how novel AgNP-antibiotic conjugates may synergistically reduce the growth of antibiotic-resistant pathogens are presented in light of promising examples, where antibiotic efficacy alone is decreased.

Antimicrobial properties of the essential oil of Schinus areira (Aguaribay) against planktonic cells and biofilms of S. aureus

The essential oil (EO) of Schinus areira L. (Anacardiaceae) leaves has shown antibacterial activity against Staphylococcus aureus. In this study we aimed to unravel the mechanisms of its antibacterial action by using bacterial cells and model membranes. First, the integrity of S. aureus membrane was evaluated by fluorescence microscopy. It was observed an increase in the permeability of cells that was dependent on the EO concentration as well as the incubation time. For a deep evaluation of the action of the EO on the lipids, its effect on the membrane fluidity was evaluated on DMPC (1,2-dimyristoyl-sn-glycero-3-phosphocholine): DMPG (1,2-dimyristoyl-sn-glycero-3-phospho-1'-rac-glycerol) (5:1) liposomes by dynamic scattering light and by using Laurdan doped liposomes. The results indicate that EO produces changes in lipid membrane packing, increasing the fluidity, reducing the cooperative cohesive interaction between phospholipids and increasing access of water or the insertion of some components of the EO to the interior of the membrane. In addition, the potential effect of EO on intracellular targets, as the increase of cytosolic reactive oxygen species (ROS) and DNA damage, were evaluated. The EO was capable of increasing the production of ROS as well as inducing a partial degradation of DNA. Finally, the effect of EO on S. aureus biofilm was tested. These assays showed that EO was able to inhibit the biofilm formation, and also eradicate preformed biofilms. The results show, that the EO seems to have several bacterial targets involved in the antibacterial activity, from the bacterial membrane to DNA. Furthermore, the antibacterial action affects not only planktonic cells but also biofilms; reinforcing the potential application for this EO.

Synergistic Antifungal Interaction between Pseudomonas aeruginosa LV Strain Metabolites and Biogenic Silver Nanoparticles against Candida auris

Candida auris has been found to be a persistent colonizer of human skin and a successful pathogen capable of causing potentially fatal infection, especially in immunocompromised individuals. This fungal species is usually resistant to most antifungal agents and has the ability to form biofilms on different surfaces, representing a significant therapeutic challenge. Herein, the effect of metabolites of Pseudomonas aeruginosa LV strain, alone and combined with biologically synthesized silver nanoparticles (bioAgNP), was evaluated in planktonic and sessile (biofilm) cells of C. auris. First, the minimal inhibitory and fungicidal concentration values of 3.12 and 6.25 μg/mL, respectively, were determined for F4a, a semi-purified bacterial fraction. Fluopsin C and indolin-3-one seem to be the active components of F4a. Like the semi-purified fraction, they showed a time- and dose-dependent fungicidal activity. F4a and bioAgNP caused severe changes in the morphology and ultrastructure of fungal cells. F4a and indolin-3-one combined with bioAgNP exhibited synergistic fungicidal activity against planktonic cells. F4a, alone or combined with bioAgNP, also caused a significant decrease in the number of viable cells within the biofilms. No cytotoxicity to mammalian cells was detected for bacterial metabolites combined with bioAgNP at synergistic concentrations that presented antifungal activity. These results indicate the potential of F4a combined with bioAgNP as a new strategy for controlling C. auris infections.

Antibacterial and biofilm-inhibitory effects of vancomycin-loaded mesoporous silica nanoparticles on methicillin-resistant staphylococcus aureus and gram-negative bacteria

The present study aimed to prepare and characterize vancomycin-loaded mesoporous silica nanoparticles (Van-MSNs) to detect inhibitory effects on the planktonic and biofilm forms of methicillin-resistant Staphylococcus aureus (MRSA) isolates, and study the biocompatibility and toxicity of Van-MSNs in vitro as well as antibacterial activity of Van-MSNs against Gram-negative bacteria. The inhibitory effects of Van-MSNs were investigated on MRSA using the determination of minimum inhibitory (MIC) and minimum biofilm-inhibitory concentrations (MBIC) as well as the effect on bacterial attachment. Biocompatibility was studied by examining the effect of Van-MSNs on the lysis and sedimentation rate of red blood cells (RBC). The interaction of Van-MSNs with human blood plasma was detected by the SDS-PAGE approach. The cytotoxic effect of the Van-MSNs on human bone marrow mesenchymal stem cells (hBM-MSCs) was evaluated by the MTT assay. The antibacterial effects of vancomycin and Van-MSNs on Gram-negative bacteria were also investigated using MIC determination using the broth microdilution method. Furthermore, bacteria outer membrane (OM) permeabilization was determined. Van-MSNs showed inhibitory effects on planktonic and biofilm forms of bacteria on all isolates at levels lower than MICs and MBICs of free vancomycin, but the antibiofilm effect of Van-MSNs was not significant. However, Van-MSNs did not affect bacterial attachment to surfaces. Van-loaded MSNs did not show a considerable effect on the lysis and sedimentation of RBC. A low interaction of Van-MSNs was detected with albumin (66.5 kDa). The hBM-MSCs viability in exposure to different levels of Van-MSNs was 91-100%. MICs of ≥ 128 µg/mL were observed for vancomycin against all Gram-negative bacteria. In contrast, Van-MSNs exhibited modest antibacterial activity inhibiting the tested Gram-negative bacterial strains, at concentrations of ≤ 16 µg/mL. Van-MSNs increased the OM permeability of bacteria that can increase the antimicrobial effect of vancomycin. According to our findings, Van-loaded MSNs have low cytotoxicity, desirable biocompatibility, and antibacterial effects and can be an option for the battle against planktonic MRSA.

Silver Is Not Equal to Silver: Synthesis and Evaluation of Silver Nanoparticles with Low Biological Activity, and Their Incorporation into C12Alanine-Based Hydrogel

A new type of silver nanoparticles (AgNPs) was prepared and comprehensively studied. Scanning electron microscopy (SEM) and dynamic light scattering (DLS) analyses indicated that 24 nm AgNPs with narrow size distribution were obtained while Z-potential confirms their good stability. The composites of the obtained AgNPs with nontoxic-nature-inspired hydrogel were formed upon cooling of the aqueous solution AgNPs and C₁₂Ala. The thermal gravimetric analysis (TGA) and the differential scanning calorimetry (DSC) do not show significant shifts in the characteristic temperature peaks for pure and silver-enriched gels, which indicates that AgNPs do not strongly interact with C₁₂Ala fibers, which was also confirmed by SEM. Both AgNPs alone and in the assembly with the gelator C₁₂Ala were almost biologically passive against bacteria, fungus, cancer, and nontumor human cells, as well as zebra-fish embryos. These studies proved that the new inactive AgNPs-doped hydrogels have potential for the application in therapy as drug delivery media.

Metallic Nanosystems in the Development of Antimicrobial Strategies with High Antimicrobial Activity and High Biocompatibility

Antimicrobial resistance is a major and growing global problem and new approaches to combat infections caused by antibiotic resistant bacterial strains are needed. In recent years, increasing attention has been paid to nanomedicine, which has great potential in the development of controlled systems for delivering drugs to specific sites and targeting specific cells, such as pathogenic microbes. There is continued interest in metallic nanoparticles and nanosystems based on metallic nanoparticles containing antimicrobial agents attached to their surface (core shell nanosystems), which offer unique properties, such as the ability to overcome microbial resistance, enhancing antimicrobial activity against both planktonic and biofilm embedded microorganisms, reducing cell toxicity and the possibility of reducing the dosage of antimicrobials. The current review presents the synergistic interactions within metallic nanoparticles by functionalizing their surface with appropriate agents, defining the core structure of metallic nanoparticles and their use in combination therapy to fight infections. Various approaches to modulate the biocompatibility of metallic nanoparticles to control their toxicity in future medical applications are also discussed, as well as their ability to induce resistance and their effects on the host microbiome.

Preparation of rutin-loaded mesoporous silica nanoparticles and evaluation of its physicochemical, anticancer, and antibacterial properties

BACKGROUND

The studies have shown that rutin has great potential as an anticancer and antimicrobial plant base agent; nevertheless, poor bioavailability and low aqueous solubility of rutin limit its application. One of the beneficial routes to increase the solubility and bioavailability of rutin is the development of nanoparticulate material. This study aimed to assess the anticancer and antibacterial effects of rutin-loaded mesoporous silica nanoparticles (RUT-MSNs).

METHODS

RUT-MSNs were prepared and physicochemically characterized. The cytotoxicity of RUT-MSNs on the HN5 cells as head and neck cancer cells was evaluated. The expression level of apoptosis-related genes such as Bcl-2 and Bax genes were evaluated. In addition, ROS production of RUT-MSNs treated cells was assessed. In addition, minimum inhibitory concentration (MIC), biofilm, and attachment inhibitory effects of RUT-MSNs compared with free rutin were assessed against different bacterial strains.

RESULTS

Transmission electron microscopy (TEM) showed mesoporous rod-shaped nanoparticles with an average particle size of less than 100 nm. RUT-MSNs displayed the cytotoxic effect with IC₅₀ of 20.23 µM in 48 h of incubation time (p < 0.05). The elevation in the ratio of Bax/Bcl-2 was displayed within the IC₅₀ concentration of RUT-MSNs in 48 h (p < 0.05). The antibacterial action of rutin was improved by loading rutin in MSNs to the nano-sized range in the MIC test.

CONCLUSION

The anticancer and antibacterial effects of RUT-MSNs were considerably more than rutin. RUT-MSNs inhibited the growth of HN5 cells by inducing apoptosis and producing ROS. These results suggest that RUT-MSNs may be useful in the treatment of cancers and infections.

Antibacterial Pathways in Transition Metal-Based Nanocomposites: A Mechanistic Overview

Across the planet, outbreaks of bacterial illnesses pose major health risks and raise concerns. Photodynamic, photothermal, and metal ion release effects of transition metal-based nanocomposites (TMNs) were recently shown to be highly effective in reducing bacterial resistance and upsurges in outbreaks. Surface plasmonic resonance, photonics, crystal structures, and optical properties of TMNs have been used to regulate metal ion release, produce oxidative stress, and generate heat for bactericidal applications. The superior properties of TMNs provide a chance to investigate and improve their antimicrobial actions, perhaps leading to therapeutic interventions. In this review, we discuss three alternative antibacterial strategies based on TMNs of photodynamic therapy, photothermal therapy, and metal ion release and their mechanistic actions. The scientific community has made significant efforts to address the safety, effectiveness, toxicity, and biocompatibility of these metallic nanostructures; significant achievements and trends have been highlighted in this review. The combination of therapies together has borne significant results to counter antimicrobial resistance (4-log reduction). These three antimicrobial pathways are separated into subcategories based on recent successes, highlighting potential needs and challenges in medical, environmental, and allied industries.

Biofilm formation of pathogenic bacteria isolated from aquatic animals

Bacterial biofilm formation is one of the dynamic processes, which facilitates bacteria cells to attach to a surface and accumulate as a colony. With the help of biofilm formation, pathogenic bacteria can survive by adapting to their external environment. These bacterial colonies have several resistance properties with a higher survival rate in the environment. Especially, pathogenic bacteria can grow as biofilms and can be protected from antimicrobial compounds and other substances. In aquaculture, biofilm formation by pathogenic bacteria has emerged with an increased infection rate in aquatic animals. Studies show that Vibrio anguillarum, V. parahaemolyticus, V. alginolyticus, V. harveyi, V. campbellii, V. fischeri, Aeromonas hydrophila, A. salmonicida, Yersinia ruckeri, Flavobacterium columnare, F. psychrophilum, Piscirickettsia salmonis, Edwardsiella tarda, E. ictaluri, E. piscicida, Streptococcus parauberis, and S. iniae can survive in the environment by transforming their planktonic form to biofilm form. Therefore, the present review was intended to highlight the principles behind biofilm formation, major biofilm-forming pathogenic bacteria found in aquaculture systems, gene expression of those bacterial biofilms and possible controlling methods. In addition, the possibility of these pathogenic bacteria can be a serious threat to aquaculture systems.

Novel Antibacterial, Cytotoxic and Catalytic Activities of Silver Nanoparticles Synthesized from Acidophilic Actinobacterial SL19 with Evidence for Protein as Coating Biomolecule

Silver nanoparticles (AgNPs) have potential applications in medicine, photocatalysis, agriculture, and cosmetic fields due to their unique physicochemical properties and strong antimicrobial activity. Here, AgNPs were synthesized using actinobacterial SL19 strain, isolated from acidic forest soil in Poland, and confirmed by UV-vis and FTIR spectroscopy, TEM, and zeta potential analysis. The AgNPs were polydispersed, stable, spherical, and small, with an average size of 23 nm. The FTIR study revealed the presence of bonds characteristic of proteins that cover nanoparticles. These proteins were then studied by using liquid chromatography with tandem mass spectrometry (LC-MS/ MS) and identified with the highest similarity to hypothetical protein and porin with molecular masses equal to 41 and 38 kDa, respectively. Our AgNPs exhibited remarkable antibacterial activity against Escherichia coli and Pseudomonas aeruginosa. The combined, synergistic action of these synthesized AgNPs with commercial antibiotics (ampicillin, kanamycin, streptomycin, and tetracycline) enabled dose reductions in both components and increased their antimicrobial efficacy, especially in the case of streptomycin and tetracycline. Furthermore, the in vitro activity of the AgNPs on human cancer cell lines (MCF-7, A375, A549, and HepG2) showed cancer-specific sensitivity, while the genotoxic activity was evaluated by Ames assay, which revealed a lack of mutagenicity on the part of nanoparticles in Salmonella Typhimurium TA98 strain. We also studied the impact of the AgNPs on the catalytic and photocatalytic degradation of methyl orange (MO). The decomposition of MO was observed by a decrease in intensity of absorbance within time. The results of our study proved the easy, fast, and efficient synthesis of AgNPs using acidophilic actinomycete SL19 strain and demonstrated the remarkable potential of these AgNPs as anticancer and antibacterial agents. However, the properties and activity of such particles can vary by biosynthesized batch.

Dissolvable wound dressing loaded with silver nanoparticles together with ampicillin and ciprofloxacin

Aim: The current study is focused on the development of water-soluble wound dressings, which are potential dressings for the treatment of burn wounds. Materials & methods: Sodium alginate-based dissolvable wound dressings were prepared and loaded with silver nanoparticles and various antibiotics (ampicillin and ciprofloxacin) followed by characterization and in vitro antibacterial studies. Results & conclusions: The prepared sodium alginate-based dissolvable wound dressing exhibited good porosity, water uptake and moisture content, promising antibacterial activity, high absorption capacity of simulated wound exudates, excellent water vapor transmission rate in the range of 2000 to 5000 g/m² day^-1, sustained drug-release profiles and water solubility. The wound dressings were active against Proteus mirabilis, Staphylococcus aureus, Proteus vulgaris, Escherichia coli and Klebsiella aeruginosa strains of bacteria. The results obtained revealed the wound dressing as potential wound dressings for burn wounds and sensitive skin.

Synergetic Antimicrobial Effect of Silver Nanoparticles Conjugated with Iprodione against Valsa mali

Apple tree canker induced by Valsamali is a vital disease in apple production around the world, and it highlyimpacts the development of apple industry. It is of great significance to study the inhibition effect of common fungicides and develop new fungistats for comprehensive control of apple tree canker. In this experiment, the inhibition activity of five fungicides, including mancozeb, metalaxyl, iprodione, prochloraz, and difenoconazole along with biosynthesized nanosilver against V. mali, were measured with the mycelium growth rate and agar well diffusion methods. The results showed that iprodione exhibited the best inhibitory effect, the median inhibition concentration (IC₅₀) of iprodione and nanosilver was 0.62 μg.mL⁻¹ and 45.50 μg.mL⁻¹, the suppression rate achieved 67.93% at 200 μg.mL⁻¹ of nanosilver. Moreover, a remarkable additive and synergistic antimicrobial effect was verified when silver nanoparticles were conjugated with iprodione at 9:1, 8:2, 7:3, and 6:4 (v/v), and the toxicity ratio was 1.04, 1.13, 1.01, and 0.98, respectively. It is proven that biosynthesized silver nanoparticles could effectively inhibit Valsamali, and it is possible to develop and screen silver nanoparticle-based nano pesticides to manage plant diseases synthetically.

Effectiveness and Applications of a Metal-Coated HNT/Polylactic Acid Antimicrobial Filtration System

A broad-spectrum antimicrobial respiration apparatus designed to fight bacteria, viruses, fungi, and other biological agents is critical in halting the current pandemic's trajectory and containing future outbreaks. We applied a simple and effective electrodeposition method for metal (copper, silver, and zinc) coating the surface of halloysite nanotubes (HNTs). These nanoparticles are known to possess potent antiviral and antimicrobial properties. Metal-coated HNTs (mHNTs) were then added to polylactic acid (PLA) and extruded to form an mHNT/PLA 3D composite printer filament. Our composite 3D printer filament was then used to fabricate an N95-style mask with an interchangeable/replaceable filter with surfaces designed to inactivate a virus and kill bacteria on contact, thus reducing deadly infections. The filter, made of a multilayered antimicrobial/mHNT blow spun polymer and fabric, is disposable, while the mask can be sanitized and reused. We used several in vitro means of assessing critical clinical features and assessed the bacterial growth inhibition against commonly encountered bacterial strains. These tests demonstrated the capability of our antimicrobial filament to fabricate N95 masks and filters that possessed antibacterial capabilities against both Gram-negative and Gram-positive bacteria.

Synergistic Effects Between Metal Nanoparticles and Commercial Antimicrobial Agents: A Review

Nanotechnology has expanded into a broad range of clinical applications. In particular, metal nanoparticles (MNPs) display unique antimicrobial properties, a fundamental function of novel medical devices. The combination of MNPs with commercial antimicrobial drugs (e.g., antibiotics, antifungals, and antivirals) may offer several opportunities to overcome some disadvantages of their individual use and enhance effectiveness. MNP conjugates display multiple advantages. As drug delivery systems, the conjugates can extend the circulation of the drugs in the body, facilitate intercellular targeting, improve drug stabilization, and possess superior delivery. Concomitantly, they reduce the required drug dose, minimize toxicity, and broaden the antimicrobial spectrum. In this work, the common strategies to combine MNPs with clinically used antimicrobial agents are underscored. Furthermore, a comprehensive survey about synergistic antimicrobial effects, the mechanism of action, and cytotoxicity is depicted.

Restoration of antibacterial activity of inactive antibiotics via combined treatment with a cyanographene/Ag nanohybrid

The number of antibiotic-resistant bacterial strains is increasing due to the excessive and inappropriate use of antibiotics, which are therefore becoming ineffective. Here, we report an effective way of enhancing and restoring the antibacterial activity of inactive antibiotics by applying them together with a cyanographene/Ag nanohybrid, a nanomaterial that is applied for the first time for restoring the antibacterial activity of antibiotics. The cyanographene/Ag nanohybrid was synthesized by chemical reduction of a precursor material in which silver cations are coordinated on a cyanographene sheet. The antibacterial efficiency of the combined treatment was evaluated by determining fractional inhibitory concentrations (FIC) for antibiotics with different modes of action (gentamicin, ceftazidime, ciprofloxacin, and colistin) against the strains Escherichia coli, Pseudomonas aeruginosa, and Enterobacter kobei with different resistance mechanisms. Synergistic and partial synergistic effects against multiresistant strains were demonstrated for all of these antibiotics except ciprofloxacin, which exhibited an additive effect. The lowest average FICs equal to 0.29 and 0.39 were obtained for colistin against E. kobei and for gentamicin against E. coli, respectively. More importantly, we have experimentally confirmed for the first time, that interaction between the antibiotic's mode of action and the mechanism of bacterial resistance strongly influenced the combined treatment’s efficacy.

A C∧S-Cyclometallated Gold(III) Complex as a Novel Antibacterial Candidate Against Drug-Resistant Bacteria

The worldwide emergence and spread of infections caused by multidrug-resistant bacteria endangers the efficacy of current antibiotics in the clinical setting. The lack of new antibiotics in the pipeline points to the need of developing new strategies. Recently, gold-based drugs are being repurposed for antibacterial applications. Among them, gold(III) complexes have received increasing attention as metal-based anticancer agents. However, reports on their antibacterial activity are scarce due to stability issues. The present work demonstrates the antibacterial activity of the gold(III) complex 2 stabilized as C∧S-cycloaurated containing a diphenylphosphinothioic amide moiety, showing minimum inhibitory concentration (MIC) values that ranged from 4 to 8 and from 16 to 32 mg/L among Gram-positive and Gram-negative multidrug-resistant (MDR) pathogens, respectively. Complex 2 has a biofilm inhibitory activity of only two to four times than its MIC. We also describe for the first time a potent antibacterial synergistic effect of a gold(III) complex combined with colistin, showing a bactericidal effect in less than 2 h; confirming the role of the outer membrane as a permeability barrier. Complex 2 shows a low rate of internalization in Staphylococcus aureus and Acinetobacter baumannii; it does not interact with replication enzymes or efflux pumps, causes ultrastructural damages in both membrane and cytoplasmic levels, and permeabilizes the bacterial membrane. Unlike control antibiotics, complex 2 did not generate resistant mutants in 30-day sequential cultures. We detected lower cytotoxicity in a non-tumoral THLE-2 cell line (IC50 = 25.5 μM) and no acute toxicity signs in vivo after an i.v. 1-mg/kg dose. The characterization presented here reassures the potential of complex 2 as a new chemical class of antimicrobial agents.

Impact of a Novel Anticoccidial Analogue on Systemic Staphylococcus aureus Infection in a Bioluminescent Mouse Model

In this study, we investigated the potential of an analogue of robenidine (NCL179) to expand its chemical diversity for the treatment of multidrug-resistant (MDR) bacterial infections. We show that NCL179 exhibits potent bactericidal activity, returning minimum inhibitory concentration/minimum bactericidal concentrations (MICs/MBCs) of 1–2 µg/mL against methicillin-resistant Staphylococcus aureus, MICs/MBCs of 1–2 µg/mL against methicillin-resistant S. pseudintermedius and MICs/MBCs of 2–4 µg/mL against vancomycin-resistant enterococci. NCL179 showed synergistic activity against clinical isolates and reference strains of Acinetobacter baumannii, Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa in the presence of sub-inhibitory concentrations of colistin, whereas NCL179 alone had no activity. Mice given oral NCL179 at 10 mg/kg and 50 mg/kg (4 × doses, 4 h apart) showed no adverse clinical effects and no observable histological effects in any of the organs examined. In a bioluminescent S. aureus sepsis challenge model, mice that received four oral doses of NCL179 at 50 mg/kg at 4 h intervals exhibited significantly reduced bacterial loads, longer survival times and higher overall survival rates than the vehicle-only treated mice. These results support NCL179 as a valid candidate for further development to treat MDR bacterial infections as a stand-alone antibiotic or in combination with existing antibiotic classes.

Tailoring of Novel Azithromycin-Loaded Zinc Oxide Nanoparticles for Wound Healing

Skin is the largest mechanical barrier against invading pathogens. Following skin injury, the healing process immediately starts to regenerate the damaged tissues and to avoid complications that usually include colonization by pathogenic bacteria, leading to fever and sepsis, which further impairs and complicates the healing process. So, there is an urgent need to develop a novel pharmaceutical material that promotes the healing of infected wounds. The present work aimed to prepare and evaluate the efficacy of novel azithromycin-loaded zinc oxide nanoparticles (AZM-ZnONPs) in the treatment of infected wounds. The Box-Behnken design and response surface methodology were used to evaluate loading efficiency and release characteristics of the prepared NPs. The minimum inhibitory concentration (MIC) of the formulations was determined against Staphylococcus aureus and Escherichia coli. Moreover, the anti-bacterial and wound-healing activities of the AZM-loaded ZnONPs impregnated into hydroxyl propyl methylcellulose (HPMC) gel were evaluated in an excisional wound model in rats. The prepared ZnONPs were loaded with AZM by adsorption. The prepared ZnONPs were fully characterized by XRD, EDAX, SEM, TEM, and FT-IR analysis. Particle size distribution for the prepared ZnO and AZM-ZnONPs were determined and found to be 34 and 39 nm, respectively. The mechanism by which AZM adsorbed on the surface of ZnONPs was the best fit by the Freundlich model with a maximum load capacity of 160.4 mg/g. Anti-microbial studies showed that AZM-ZnONPs were more effective than other controls. Using an experimental infection model in rats, AZM-ZnONPs impregnated into HPMC gel enhanced bacterial clearance and epidermal regeneration, and stimulated tissue formation. In conclusion, AZM -loaded ZnONPs are a promising platform for effective and rapid healing of infected wounds.

Green, novel, and one-step synthesis of silver oxide nanoparticles: antimicrobial activity, synergism with antibiotics, and cytotoxic studies

Silver oxide nanoparticles (Ag2ONPs) were synthesized by a one-step, green, and novel method. Ag2ONPs were characterized independently as well as in mixtures with common antibiotics. The antibacterial activity of Ag2ONPs...

Biogenic Silver Nanoparticles: Synthesis and Application as Antibacterial and Antifungal Agents

The importance and need for eco-oriented technologies has increased worldwide, which leads to an enhanced development of methods for the synthesis of nanoparticles using biological agents. This review de-scribes the current approaches to the preparation of biogenic silver nanoparticles, using plant extracts and filtrates of fungi and microorganisms. The peculiarities of the synthesis of particles depending on the source of biocomponents are considered as well as physico-morphological, antibacterial and antifungal properties of the resulting nanoparticles which are compared with such properties of silver nanoparticles obtained by chemical synthesis. Special attention is paid to the process of self-assembly of biogenic silver nanoparticles.

Silver nanoparticles as a bioadjuvant of antibiotics against biofilm-mediated infections with methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa in chronic rhinosinusitis patients

Infectious diseases caused by antibiotic-resistant bacteria in planktonic and biofilm form are difficult to treat with conventional antibiotics. Silver nanoparticles (Ag NPs) can be used as alternatives to antibiotics and can alter the susceptibility of bacteria to antibiotics. Here, the antibacterial properties of 16 different antibiotics and Ag NPs, alone and in combination, were tested against clinical isolates of Pseudomonas aeruginosa (n=3), Staphylococcus aureus (n=3) and methicillin-resistant Staphylococcus aureus (MRSA) (n=2) isolated from chronic rhinosinusitis (CRS) patients. The microdilution method and resazurin assay were used to determine the minimum inhibitory concentration and minimum biofilm eradication concentration for planktonic and biofilm forms, respectively. Results showed that Ag NPs and gentamicin combinations had synergistic antibacterial activity against P. aeruginosa planktonic and biofilm forms and MRSA biofilms. Furthermore, additive effects against biofilms were seen for combinations of Ag NPs with tobramycin or ciprofloxacin against P. aeruginosa; with mupirocin against MRSA; and with augmentin, doxycycline, azithromycin and clindamycin against S. aureus. Moreover, additive effects against planktonic forms were observed for combinations of Ag NPs with tobramycin, ciprofloxacin, imipenem, ceftazidime and aztreonam against P. aeruginosa; with gentamicin or linezolid against MRSA; and with doxycycline or clindamycin against S. aureus. In conclusion, Ag NP-antibiotic combinations can result in enhanced antimicrobial action against P. aeruginosa, MRSA and S. aureus clinical isolates in planktonic and biofilm forms and can be used in the context of CRS with confirmed infection.