Chitosan nanoparticles loaded with the antimicrobial peptide temporin B exert a long-term antibacterial activity in vitro against clinical isolates of Staphylococcus epidermidis

pH/Hyal-responsive vancomycin-loaded chitooligosaccharide nanoparticles for intracellular MRSA infection treatment

Staphylococcus aureus (S. aureus) is recognized as among the most critical bacterial pathogens globally. A significant portion of the complications associated with S. aureus infections arises from its ability to persist inside host phagocytes, particularly macrophages, making the eradication of intracellular S. aureus vital for therapeutic success. Regrettably, many antibiotics exhibit limited penetration into cells, underscoring the necessity for efficient intracellular delivery mechanisms. In this study, vancomycin-loaded chitooligosaccharide nanoparticles (COS@Van) coated with hyaluronic acid (HA), were engineered to function as an active-targeting antibiotic carrier recorded as HA/COS@Van. The HA coating serves as an external shell, which 1) covers the positive surface charge of COS NPs, thereby enhancing their biocompatibility and extending circulation time, and 2) facilitates targeted delivery to macrophages through specific interactions with the CD44 receptor. Confocal laser scanning microscopy (CLSM) and flow cytometry (FCM) experiments confirmed that HA/COS could effectively accumulate in methicillin-resistant S. aureus (MRSA) infected macrophages. Additionally, when administered intravenously in mouse models, HA/COS demonstrated markedly increased accumulation in the liver, the primary location of infected macrophages. These findings highlight the active-targeting capabilities of HA/COS both in vitro and in vivo settings. Consequently, after being loaded with Van, HA/COS@Van exhibited superior efficacy in killing intracellular MRSA in vitro, as compared to free Van. Furthermore, HA/COS@Van also demonstrated enhanced bactericidal activity in both mouse acute peritonitis model and mouse organ infection model. Therefore, this active-targeting delivery system may hold promise in advancing therapeutic outcomes for infections related to intracellular pathogens.

Developing antibacterial HB43 peptide-loaded chitosan nanoparticles for biofilm treatment

Biofilm-associated infections on medical devices are challenging to treat. Therefore, innovative treatment approaches are needed to penetrate biofilms and eliminate bacteria. With this study, we developed chitosan nanoparticles (CNPs) encapsulating the antibacterial peptide HB43 at increasing CNP/peptide ratios (from 1 to 4 % for P1-CNP, P2-CNP, and P4-CNP, respectively) using the ion gelation method. Our goal was to enhance antibacterial drug delivery inside a methicillin-resistant Staphylococcus aureus (MRSA) biofilm. Our analysis showed a direct correlation between the encapsulation efficacy of HB43 and the physical properties of the CNPs, such as size and zeta potential. P1-CNP was identified as the optimal formulation, characterized by its small size, high encapsulation efficiency, and cationic surface charge. Release studies indicated that HB43 was released in a sustained manner particularly under acidic conditions, which enhanced therapeutic efficacy. We tested the P1-CNP in culture media with pH levels of 7.4 and 5.5 to assess the pH responsiveness of the CNPs and mimic the infection environment. Both conditions showed that the HB43 loaded-CNPs effectively reduced bacterial populations in a dose-dependent manner, with up to a 99.99 % reduction in bacterial load. This study offers a promising new strategy for managing biofilm-associated infections and addressing antibiotic resistance by using CNPs loaded with HB43.

Optimization of Achillea millefolium-Infused Chitosan Nanocarriers for Antibacterial and Dye Degradation Applications

The demand for plant-based nanocarriers and nanodrugs is increasing due to their versatile nature and compatibility. This research focuses on the optimization of Achillea millefolium-infused chitosan (CS) nanocarriers for antibacterial and dye degradation applications, emphasizing the novelty of this approach. Different dilutions of A. millefolium were loaded into low-molecular (LM)- and high-molecular-weight-CS nanocarriers using the ionotropic gelation method. The synthesized drug-loaded CS nanocarriers were characterized using ultraviolet (UV)-visible (Vis) spectroscopy, scanning electron microscopy, dynamic light scattering, Fourier-Transform Infrared, and high-performance liquid chromatography. The optimized nanocarriers were further analyzed for encapsulation efficiency (EE), antibacterial activity, and dye degradation capacity. The EE of the drug-loaded CS nanocarriers ranged from 15% to 100%. Notably, the LM-weight-CS-based nanocarriers demonstrated a significant dye degradation capacity, achieving an impressive 83% degradation rate for methylene orange (MO). Moreover, these nanoparticles (NPs) exhibited superior efficacy compared to un-immobilized counterparts. The A. millefolium-CS NPs also significantly enhanced the zone of inhibition against Escherichia coli and Staphylococcus aureus, demonstrating strong antibacterial potential. These results underscore the enhanced ability of the CS NP formulation to inhibit microbial growth and effectively degrade dyes. The combination of A. millefolium and CS NPs showcases potential for innovative therapeutic applications, particularly in wastewater treatment and antimicrobial therapies. This study provides novel insights into the development of effective plant-based nanocarriers, paving the way for future research in this field.

Stigmurin encapsulated PLA-PEG ameliorates its therapeutic potential, antimicrobial and antiproliferative activities

In light of growing global challenge posed by antimicrobial resistance, it is very important to explore alternatives that can target pathogenic microorganisms. One such strategy involves the use of antimicrobial peptides (AMPs) and Stigmurin is one such AMP present in Brazilian scorpion Tityus stigmurus which possesses antimicrobial, antiproliferative and antiparasitic activity. The study commenced with successful synthesis and characterization of Stigmurin and its analogues, designated S1 and S2. Studies on Stigmurin and its analogues have demonstrated that analogues exhibit enhanced antimicrobial efficacy but often lead to increased hemolysis, limiting their therapeutic application. To prevent the associated toxicity of these peptides, PLA-PEG di-block copolymer was synthesised to prepare nanoparticles (E-WT, E1, and E2) with an average diameter of approximately 160-180 nm. The core of the research involved evaluating the antimicrobial (Bacillus subtilis), antibiofilm (B. subtilis and Pseudomonas aeruginosa), antiproliferative (HEK293 and RAW264.7) and hemolytic activity of the peptides. In addition to the experimental work, in silico analysis using structural models was conducted to further understand their potential interactions. The findings demonstrated that the analogue peptides exhibit enhanced antimicrobial and antibiofilm activity compared to the wild-type Stigmurin. Moreover, encapsulating the peptides in PLA-PEG nanoparticles maintained the antimicrobial activity against B. subtilis. Further, encapsulation significantly reduced hemolysis as well as cytotoxicity by 10-20%, thereby improving their safety profile.

Future applications of cyclic antimicrobial peptides in drug delivery

INTRODUCTION

Cyclic antimicrobial peptides (CAMPs) are gaining attention as promising candidates in advanced drug delivery systems due to their structural stability, resistance to proteolytic degradation, and versatile therapeutic potential. Their unique properties enable applications that extend beyond combating multidrug-resistant (MDR) pathogens. Their amphipathic and cell-penetrating properties allow them to efficiently transport drugs across cellular membranes.

AREAS COVERED

This review explores the structural advantages and mechanisms of action of CAMPs, emphasizing their role in drug delivery. The literature analysis (2010-2024) from PubMed, Scopus, and Web of Science highlights developments in CAMP-conjugated therapies, liposomal formulations, and encapsulation systems. The review also examines their antimicrobial potency, amphipathic and cell-penetrating properties, and integration into nanocarrier technologies to enhance drug stability, bioavailability, and precision targeting. Challenges such as toxicity, scalability, and cost are also discussed. CAMPs have the potential to revolutionize drug delivery through their robustness and multifunctionality, particularly in precision medicine.

EXPERT OPINION

Future advancements in peptide engineering, nanotechnology, and AI-driven design are expected to enhance CAMPs' therapeutic specificity, reduce toxicity, and broaden their applications, including oncology and gene therapy, paving the way for their integration into next-generation therapeutics.

Long-Lasting, Transparent Antibacterial Shield: A Durable, Broad-Spectrum Anti-Bacterial, Non-Cytotoxic, Transparent Nanocoating for Extended Wear Contact Lenses

The increasing incidence of serious bacterial keratitis, a sight-threatening condition often exacerbated by inadequate contact lens (CLs) care, highlights the need for innovative protective technology. This study introduces a long-lasting antibacterial, non-cytotoxic, transparent nanocoating for CLs via a solvent-free polymer deposition method, aiming to prevent bacterial keratitis. The nanocoating comprises stacked polymer films, with poly(dimethylaminomethyl styrene-co-ethylene glycol dimethacrylate) (pDE) as a biocompatible, antibacterial layer atop poly(2,4,6,8-tetramethyl-2,4,6,8-tetravinylcyclotetrasiloxane) (pV4D4) as an adhesion-promoting layer. The pD6E1-grafted (g)-pV4D4 film shows non-cytotoxicity toward two human cell lines and antibacterial activity of >99% against four bacteria, including methicillin-resistant Staphylococcus aureus (MRSA), an antibiotic-resistant bacteria and Pseudomonas aeruginosa, which causes ocular diseases. Additionally, the film demonstrates long-lasting antibacterial activity greater than 96% against MRSA for 9 weeks in phosphate-buffered saline. To the best knowledge, this duration represents the longest reported long-term stability with less than 5% decay of antibacterial performance among contact-killing antibacterial coatings. The film exhibits exceptional mechanical durability, retaining its antibacterial activity even after 15 washing cycles. The pD6E1-g-pV4D4-coated CL maintains full optical transmittance compared to that of pristine CL. It is expected that the unprecedentedly prolonged antibacterial performance of the coating will significantly alleviate the risk of infection for long-term CL users.

Surface modified proteins and peptides for targeted drug delivery

Surface modification of proteins and peptides has emerged as a promising strategy to enhance their therapeutic efficacy and target specificity. This chapter delves into the various techniques employed to modify the surface properties of these biomolecules, including chemical conjugation, site-specific mutagenesis, and peptide synthesis. The focus is on strategies that improve drug delivery to specific target sites, such as tumor cells or inflamed tissues. By modifying surface properties, it is possible to enhance drug stability, reduce immunogenicity, and prolong circulation time. This chapter explores the latest advancements in this field and discusses the potential applications of surface-modified proteins and peptides in the development of novel therapeutic agents.

Chitosan-Based Multifunctional Biomaterials as Active Agents or Delivery Systems for Antibacterial Therapy

Antibiotic therapy has been a common method for treating bacterial infections over the past century, but with the rise in bacterial resistance caused by antibiotic abuse, better control and more rational use of antibiotics have been increasingly demanded. At the same time, a journey to explore alternatives to antibiotic therapies has also been undertaken. Chitosan and its derivatives, materials with good biocompatibility, biodegradability, and excellent antibacterial properties, have garnered significant attention, and more and more studies on chitosan and its derivatives have been conducted in recent years. In this work, we aim to elucidate the biological properties of chitosan and its derivatives and to track their clinical applications, as well as to propose issues that need to be addressed and possible solutions to further their future development and application.

Tityus stigmurus-Venom-Loaded Cross-Linked Chitosan Nanoparticles Improve Antimicrobial Activity

The rapid resistance developed by pathogenic microorganisms against the current antimicrobial pool represents a serious global public health problem, leading to the search for new antibiotic agents. The scorpion Tityus stigmurus, an abundant species in Northeastern Brazil, presents a rich arsenal of bioactive molecules in its venom, with high potential for biotechnological applications. However, venom cytotoxicity constitutes a barrier to the therapeutic application of its different components. The objective of this study was to produce T. stigmurus-venom-loaded cross-linked chitosan nanoparticles (Tsv/CN) at concentrations of 0.5% and 1.0% to improve their biological antimicrobial activity. Polymeric nanoparticles were formed with a homogeneous particle size and spherical shape. Experimental formulation parameters were verified in relation to mean size (<180 nm), zeta potential, polydispersity index and encapsulation efficiency (>78%). Tsv/CN 1.0% demonstrated an ability to increase the antimicrobial venom effect against Staphylococcus aureus bacteria, exhibiting an MIC value of 44.6 μg/mL. It also inhibited different yeast species of the Candida genus, and Tsv/CN 0.5% and 1.0% led to a greater inhibitory effect of C. tropicalis and C. parapsilosis strains, presenting MIC values between 22.2 and 5.5 µg/mL, respectively. These data demonstrate the biotechnological potential of these nanosystems to obtain a new therapeutic agent with potential antimicrobial activity.

Three-Dimensional Melted Electrowriting Drug Coating Fibers for the Prevention of Device-Associated Infections: A Pilot Study

Medical device-related infections (DRIs), especially prevalent among critically ill patients, impose significant health and economic burdens and are mainly caused by bacteria. Severe infections often necessitate device removal when antibiotic therapy is inefficient, delaying recovery. To tackle this issue, PCL drug-eluting coated meshes were explored, and they were printed via melt electrowriting (MEW). These meshes were coated with gentamicin sulfate (GS) and tetracycline hydrochloride (TCH) and underwent FTIR analysis to confirm drug integration. Antimicrobial activity was assessed via agar diffusion assays and biofilm formation assays against bacterial strains: Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 43300, and Staphylococcus epidermidis ATCC 35984. FTIR analysis evidenced the presence of the drugs in the meshes. TCH displayed broad-spectrum antimicrobial activity against all strains, whereas GS was effective against all except S. aureus. These findings indicate the potential of cost-effective ultra-fine drug coating fibers for medical device applications, offering infection prevention during implantation. This preliminary study demonstrates the feasibility of producing drug-eluting fibers for DRI prevention through a non-toxic, fast, and cost-efficient technique, paving the way for enhanced patient care and reduced healthcare costs.

ULK1 Mediated Autophagy-Promoting Effects of Rutin-Loaded Chitosan Nanoparticles Contribute to the Activation of NF-κB Signaling Besides Inhibiting EMT in Hep3B Hepatoma Cells

Background

Liver cancer remains to be one of the leading causes of cancer worldwide. The treatment options face several challenges and nanomaterials have proven to improve the bioavailability of several drug candidates and their applications in nanomedicine. Specifically, chitosan nanoparticles (CNPs) are extremely biodegradable, pose enhanced biocompatibility and are considered safe for use in medicine.

Methods

CNPs were synthesized by ionic gelation, loaded with rutin (rCNPs) and characterized by ultraviolet-visible spectroscopy (UV-Vis), Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS) and transmission electron microscopy (TEM). The rCNPs were tested for their cytotoxic effects on human hepatoma Hep3B cells, and experiments were conducted to determine the mechanism of such effects. Further, the biocompatibility of the rCNPs was tested on L929 fibroblasts, and their hemocompatibility was determined.

Results

Initially, UV-vis and FTIR analyses indicated the possible loading of rutin on rCNPs. Further, the rutin load was quantitatively measured using Ultra-Performance Liquid Chromatography (UPLC) and the concentration was 88 µg/mL for 0.22 micron filtered rCNPs. The drug loading capacity (LC%) of the rCNPs was observed to be 13.29 ± 0.68%, and encapsulation efficiency (EE%) was 19.55 ± 1.01%. The drug release was pH-responsive as 88.58% of the drug was released after 24 hrs at the lysosomal pH 5.5, whereas 91.44% of the drug was released at physiological pH 7.4 after 102 hrs. The cytotoxic effects were prominent in 0.22 micron filtered samples of 5 mg/mL rutin precursor. The particle size for the rCNPs at this concentration was 144.1 nm and the polydispersity index (PDI) was 0.244, which is deemed to be ideal for tumor targeting. A zeta potential (ζ-potential) value of 16.4 mV indicated rCNPs with good stability. The IC50 value for the cytotoxic effects of rCNPs on human hepatoma Hep3B cells was 9.7 ± 0.19 μg/mL of rutin load. In addition, the increased production of reactive oxygen species (ROS) and changes in mitochondrial membrane potential (MMP) were observed. Gene expression studies indicated that the mechanism for cytotoxic effects of rCNPs on Hep3B cells was due to the activation of Unc-51-like autophagy-activating kinase (ULK1) mediated autophagy and nuclear factor kappa B (NF-κB) signaling besides inhibiting the epithelial-mesenchymal Transition (EMT). In addition, the rCNPs were less toxic on NCTC clone 929 (L929) fibroblasts in comparison to the Hep3B cells and possessed excellent hemocompatibility (less than 2% of hemolysis).

Conclusion

The synthesized rCNPs were pH-responsive and possessed the physicochemical properties suitable for tumor targeting. The particles were effectively cytotoxic on Hep3B cells in comparison to normal cells and possessed excellent hemocompatibility. The very low hemolytic profile of rCNPs indicates that the drug could be administered intravenously for cancer therapy.

Rapid eradication of vancomycin and methicillin-resistant Staphylococcus aureus by MDP1 antimicrobial peptide coated on photocrosslinkable chitosan hydrogel: in vitro antibacterial and in silico molecular docking studies

Introduction

Antibiotic resistance and weak bioavailability of antibiotics in the skin due to systemic administration leads to failure in eradication of vancomycin- and methicillin-resistant Staphylococcus aureus (VRSA and MRSA)-associated wound infections and subsequent septicemia and even death. Accordingly, this study aimed at designing a photocrosslinkable methacrylated chitosan (MECs) hydrogel coated by melittin-derived peptide 1 (MDP1) that integrated the antibacterial activity with the promising skin regenerative capacity of the hydrogel to eradicate bacteria by burst release strategy.

Methods

The MECs was coated with MDP1 (MECs-MDP1), characterized, and the hydrogel-peptide interaction was evaluated by molecular docking. Antibacterial activities of MECs-MDP1 were evaluated against VRSA and MRSA bacteria and compared to MECs-vancomycin (MECs-vanco). Antibiofilm activity of MECs-MDP1 was studied by our novel 'in situ biofilm inhibition zone (IBIZ)' assay, and SEM. Biocompatibility with human dermal fibroblast cells (HDFs) was also evaluated.

Results and Discussion

Molecular docking showed hydrogen bonds as the most interactions between MDP1 and MECs at a reasonable affinity. MECs-MDP1 eradicated the bacteria rapidly by burst release strategy whereas MECs-vanco failed to eradicate them at the same time intervals. Antibiofilm activity of MECs-MDP1 were also proved successfully. As a novel report, molecular docking analysis has demonstrated that MDP1 covers the structure of MECs and also binds to lysozyme with a reasonable affinity, which may explain the inhibition of lysozyme. MECs-MDP1 was also biocompatible with human dermal fibroblast skin cells, which indicates its safe future application. The antibacterial properties of a photocrosslinkable methacrylated chitosan-based hydrogel coated with MDP1 antimicrobial peptide were successfully proved against the most challenging antibiotic-resistant bacteria causing nosocomial wound infections; VRSA and MRSA. Molecular docking analysis revealed that MDP1 interacts with MECs mainly through hydrogen bonds with reasonable binding affinity. MECs-MDP1 hydrogels eradicated the planktonic state of bacteria by burst release of MDP1 in just a few hours whereas MECs-vanco failed to eradicate them. inhibition zone assay showed the anti-biofilm activity of the MECs-MDP1 hydrogel too. These findings emphasize that MECs-MDP1 hydrogel would be suggested as a biocompatible wound-dressing candidate with considerable and rapid antibacterial activities to prevent/eradicate VRSA/MRSA bacterial wound infections.

Antibacterial and in vitro anticancer activities of the antimicrobial peptide NRC-07 encapsulated in chitosan nanoparticles

Antimicrobial peptides (AMPs) are promising alternatives to conventional antibiotics and chemotherapy in the treatment of multidrug-resistant pathogens and drug-resistant cancers. Clinical application of AMPs is limited due to low stability and inefficient transport. Encapsulation in nanocarriers may improve their therapeutic potential. Chitosan nanoparticles (CS-NPs) are efficient carriers for proteins and peptides, improving the treatment of microbial infections and targeted drug delivery. We examined toxicity against cancer cell lines and antibacterial activities of the pleurocidin-like AMP NRC-07 upon encapsulation in CS-NPs by ionotropic gelation. The biological activities of various formulations of free and encapsulated NRC-07 and free nanoparticles were evaluated against Pseudomonas aeruginosa and breast cancer cells, using assays for cell viability and lactate dehydrogenase cytolysis with non-cancer cell lines as controls. NRC-07-containing nanoparticles decreased the bacterial and cancer cell viability in a concentration-dependent manner. Activities of encapsulated peptide were >2-fold higher than those of free NRC-07 peptide. Unloaded CS-NPs and free peptide were not cytotoxic against control cells. Encapsulation of NRC-07 into CS-NPs enhanced the antibacterial and selective cytotoxicity of the peptide, possibly enhancing anticancer activities. Encapsulation presents a promising tool for the development of efficient drug delivery systems.

Exploring the current landscape of chitosan-based hybrid nanoplatforms as cancer theragnostic

In the last decade, investigators have put significant efforts to develop several diagnostic and therapeutic strategies against cancer. Many novel nanoplatforms, including lipidic, metallic, and inorganic nanocarriers, have shown massive potential at preclinical and clinical stages for cancer diagnosis and treatment. Each of these nano-systems is distinct with its own benefits and limitations. The need to overcome the limitations of single-component nano-systems, improve their morphological and biological features, and achieve multiple functionalities has resulted in the emergence of hybrid nanoparticles (HNPs). These HNPs integrate multicomponent nano-systems with diagnostic and therapeutic functions into a single nano-system serving as promising nanotools for cancer theragnostic applications. Chitosan (CS) being a mucoadhesive, biodegradable, and biocompatible biopolymer, has emerged as an essential element for the development of HNPs offering several advantages over conventional nanoparticles including pH-dependent drug delivery, sustained drug release, and enhanced nanoparticle stability. In addition, the free protonable amino groups in the CS backbone offer flexibility to its structure, making it easy for the modification and functionalization of CS, resulting in better drug targetability and cell uptake. This review discusses in detail the existing different oncology-directed CS-based HNPs including their morphological characteristics, in-vitro/in-vivo outcomes, toxicity concerns, hurdles in clinical translation, and future prospects.

Strong Activity and No Resistance Induction Exerted by Cell-Free Supernatants from Lacticaseibacillus rhamnosus against Mono-Species and Dual-Species Biofilms of Wound Pathogens in In Vivo-like Conditions

It is widely agreed that microbial biofilms play a major role in promoting infection and delaying healing of chronic wounds. In the era of microbial resistance, probiotic strains or their metabolic products are emerging as an innovative approach for the treatment of hard-to-heal (chronic) wounds due to their antimicrobial, healing, and host immune-modulatory effects. In this study, we aimed to investigate the potential of cell-free supernatants (CFS) from Lacticaseibacillus rhamnosus GG against mono- and dual-species biofilms of wound pathogens in a 3D in vitro infection model. Mature biofilms of Pseudomonas aeruginosa and Staphylococcus aureus were obtained on collagen scaffolds in the presence of a simulant wound fluid (SWF) and treated with CFS at different doses and time intervals. At 1:4 dilution in SWF, CFS caused a marked reduction in the colony forming-unit (CFU) numbers of bacteria embedded in mono-species biofilms as well as bacteria released by the biofilms in the supernatant. CFU count and electron microscopy imaging also demonstrated a marked antibiofilm effect against dual-species biofilms starting from 8 h of incubation. Furthermore, CFS exhibited acceptable levels of cytotoxicity at 24 h of incubation against HaCaT cells and, differently from ciprofloxacin, failed to induce resistance after 15 passages at sub-inhibitory concentrations. Overall, the results obtained point to L. rhamnosus GG postbiotics as a promising strategy for the treatment of wound biofilms.

Effect of C7-3-Peptide-Loaded Chitosan Nanoparticles Against Multi-Drug-Resistant Neisseria gonorrhoeae

Introduction

The emergence of Neisseria gonorrhoeae-resistant strains represents one of the most urgent global threats. In this regard, C7-3 peptide is one of the anti-virulence therapies that has demonstrated promising anti-gonococcal activity. Accordingly, this research aimed to formulate C7-3 peptide and its derivatives in chitosan nanoparticles.

Methods

The peptide loaded chitosan nanoparticles were prepared using ion gelation method, and their physicochemical characteristics were investigated. The anti-gonococcal and antibiofilm activity of prepared NPs was assessed, and their cytotoxicity in human ovarian cells was evaluated.

Results

All prepared NPs were optimized for the smallest particle size of 136.9 to 168.3 nm. The EE% of C7-3, C7-3m1, and C7-3m2 CNPs reached 90.2, 92.5, and 91.8%, respectively. An in vitro release study demonstrated a continuous sustained-release pattern of C7-3 peptide from NPs. The SDS-PAGE assay confirmed the integrity of C7-3 peptide after the fabrication process. When comparing each peptide alone, the generated NPs demonstrated higher anti-gonococcal and anti-biofilm effectiveness against standard and resistant bacterial strains under anaerobic conditions. The cytotoxicity experiments revealed the cytocompatibility of NPs in HeLa cell lines. Given the advantages of enhanced anti-gonococcal activity of the C7-3 peptide and its derivatives when loaded with CNPs, as well as the antimicrobial properties of chitosan NPs, the reported NPs have great potential in the treatment of gonococcal infection.

ZnO/chitosan nanocomposites as a new approach for delivery LL37 and evaluation of the inhibitory effects against biofilm-producing Methicillin-resistant Staphylococcus aureus isolated from clinical samples

Modification surface of chitosan nanoparticles using ZnO nanoparticles is important interest in drug delivery because of the beneficial properties. In this study, we proposed a chitosan/ZnO nanocomposite for the targeted delivery of antibacterial peptide (LL37). Synthesized LL37-loaded chitosan/ZnO nanocomposite (CS/ZnO/LL37-NCs) was based on the ionotropic gelation method. The antibacterial activity of the synthesized platform versus Methicillin-resistant Staphylococcus aureus (MRSA) was determined by the microdilution method in 10 mM sodium phosphate buffer. The biofilm formation inhibitory was also evaluated using microtiter plate method. In addition, the ability of CS/ZnO/LL37-NCs on the icaA gene expression level was assessed by the Real-Time PCR. The loading and release investigations confirmed the suitability of CS/ZnO-NCs for LL37 encapsulation. Results showed 6 log10 CFU/ml reduction in MRSA treated with the CS/ZnO/LL37-NPs. Moreover, CS/ZnO/LL37-NCs showed 81 % biofilm formation inhibition than LL37 alone. Also, icaA gene expression decreased 1-fold in the face of CS/ZnO/LL37-NCs. In conclusion, the modification surface of chitosan nanoparticles with ZnO nanoparticles is a suitable chemical platform for the delivery of LL37 that could be used as a promising nanocarrier for enhancing the delivery of antibacterial peptide and improving the antibacterial activity of LL37.

Insights for the control of dried-fruit beetle Carpophilus hemipterus (Nitidulidae) using rosemary essential oil loaded in chitosan nanoparticles

Natural insecticidal products, essentially essential oils and their bioactive compounds are available as an excellent alternative method to control insect pests as well as they are less toxic to human health. However, due to their volatile constituents, encapsulation could be considered as the most suitable solution for their practical application. Therefore, this study aims to explore the insecticidal toxicity of chitosan nanoparticles loaded with Rosmarinus officinalis essential oil against adults of Carpophilus hemipterus. Chitosan nanoparticles were prepared by ionic gelation method with an encapsulation efficiency 41.543.1% and loading capacity 5.24G0.28%. Results revealed that chitosan nanoparticles loaded rosemary oil exhibited interesting insecticidal toxicity towards C. hemipterus adults in stored dates with 50.73% mortality. Overall, this work pointed out that the innovative design method based on chitosan-nanoparticles loaded rosemary oil can be promoted in integrated pest management program for stored date pests.

A novel antibacterial approach of Cecropin-B peptide loaded on chitosan nanoparticles against MDR Klebsiella pneumoniae isolates

Egypt has witnessed the emergence of multidrug-resistant (MDR) Klebsiella pneumoniae, which has posed a serious healthcare challenge. The proper treatment choice for MDR-KP infections is not well determined which renders the problem more complicated, thus making the control of such infections a serious challenge for healthcare professionals. This study aims to encapsulate the cationic antimicrobial peptide; Cecropin-B (Cec-B), to increase its lifetime, drug targeting, and efficacy and study the antimicrobial effect of free and encapsulated recombinant rCec-B peptide on multidrug-resistant K. pneumoniae (MDR-KP) isolates. Fifty isolates were collected from different clinical departments at Theodore Bilharz Research Institute. Minimal inhibitory concentrations (MICs) of rCec-B against MDR-KP isolates were determined by the broth microdilution test. In addition, encapsulation of rCec-B peptide into chitosan nanoparticles and studying its bactericidal effect against MDR-KP isolates were also performed. The relative expression of efflux pump and porin coding genes (ArcrB, TolC, mtdK, and Ompk35) was detected by quantitative PCR in treated MDR-KP bacterial isolates compared to untreated isolates. Out of 60 clinical MDR isolates, 50 were MDR-KP. 60% of the isolates were XDR while 40% were MDR. rCec-B were bactericidal on 21 isolates, then these isolates were subjected to treatment using free nanocapsule in addition to the encapsulated peptide. Free capsules showed a mild cytotoxic effect on MDR-KP at the highest concentration. MIC of encapsulated rCec-B was higher than the free peptide. The expression level of genes encoding efflux and porin (ArcrB, TolC, mtdK, and Ompk35) was downregulated after treatment with encapsulated rCec-B. These findings indicate that encapsulated rCec-B is a promising candidate with potent antibacterial activities against drug-resistant K. pneumoniae.

Fabrication of bioactive nanocomposites from chitosan, cress mucilage, and selenium nanoparticles with powerful antibacterial and anticancerous actions

Natural bioactive alternatives are the utmost requests from researchers to provide biosafe and effectual health-guarding agents. The biopolymers chitosan nanoparticles (NCT), mucilage of cress seed (GCm; Lepidium sativum), and GCm-mediated selenium nanoparticles (GCm/SeNPs) were innovatively employed for fabricating novel bioactive natural nanocomposites (NCs) with elevated bioactivities as bactericidal (against Salmonella typhimurium and Staphylococcus aureus) and anticancer (against CaCo-2 and HeLa cells). The SeNPs were successfully generated with GCm, and different NCs formulations were fabricated from NCT:GCm/SeNPs amalgam ratios including T1, T2, and T3 with 2:1, 1:1, and 1:2 ratios, respectively. The infrared analysis of synthesized molecules appointed apparent physical interactions among interacted molecules. The average particles' sizes and charges of molecules/NCs were (12.7, 316.4, 252.8, and 127.3 nm) and (-6.9, +38.7, +26.2, and -25.8 mV) for SeNPs, T1, T2, and T3, respectively. The biocidal assessment of NCs indicated that T1 was the strongest antibacterial formulation, whereas T3 was the superior anticancer amalgam. These NCs formulations could exceed the biocidal potentialities of standard biocides. T1-NC could cause severe destructions/deformations in challenged S. typhimurium within 9 h, whereas T3-NCs induced apparent fluorescent apoptosis signs in treated HeLa cells. The prospective applications innovatively designed biocidal natural NCs that are recommended for controlling pathogenic bacteria and fighting cancerous cells.

Transient Coatings from Nanoparticles Achieving Broad-Spectrum and High Antimicrobial Performance

Cationic and hydrophilic coatings based on casting and drying water dispersions of two different nanoparticles (NPs) onto glass are here described and evaluated for antimicrobial activity. Discoid cationic bilayer fragments (BF) surrounded by carboxy-methylcellulose (CMC) and poly (diallyl dimethyl ammonium) chloride (PDDA) NPs and spherical gramicidin D (Gr) NPs dispersed in water solution were cast onto glass coverslips and dried, forming a coating quantitatively evaluated against Pseudomonas aeruginosa, Staphylococcus aureus and Candida albicans. From plating and colony forming units (CFU) counting, all strains interacting for 1 h with the coatings lost viability from 10⁵ to 10⁶, to zero CFU, at two sets of Gr and PDDA doses: 4.6 and 25 μg, respectively, or, 0.94 and 5 μg, respectively. Combinations produced broad spectrum, antimicrobial coatings; PDDA electrostatically attached to the microbes damaging cell walls, allowing Gr NPs interaction with the cell membrane. This concerted action promoted optimal activity at low Gr and PDDA doses. Further washing and drying of the deposited dried coatings showed that they were washed out so that antimicrobial activity was no longer present on the glass surface. Significant applications in biomedical materials can be foreseen for these transient coatings.

Control and prevention of microbially influenced corrosion using cephalopod chitosan and its derivatives: A review

Microbially influenced corrosion (MIC) of metals is an important industrial problem, causing 300-500 billion dollars of economic loss worldwide each year. It is very challenging to prevent or control the MIC in the marine environment. Eco-friendly coatings embedded with corrosion inhibitors developed from natural products may be a successful approach for MIC prevention or control. As a natural renewable resource, cephalopod chitosan has a number of unique biological properties, such as antibacterial, antifungal and non-toxicity effects, which attract scientific and industrial interests for potential applications. Chitosan is a positively charged molecule, and the negatively charged bacterial cell wall is the target of its antimicrobial action. Chitosan binds to the bacterial cell wall and disrupts the normal functions of the membrane by, for example, facilitating the leakage of intracellular components and impeding the transport of nutrients into the cells. Interestingly, chitosan is an excellent film-forming polymer. Chitosan may be applied as an antimicrobial coating substance for the prevention or control of MIC. Furthermore, the antimicrobial chitosan coating can serve as a basal matrix, in which other antimicrobial or anticorrosive substances like chitosan nanoparticles, chitosan silver nanoparticles, quorum sensing inhibitors (QSI) or the combination of these compounds, can be embedded to achieve synergistic anticorrosive effects. A combination of field and laboratory experiments will be conducted to test this hypothesis for preventing or controlling MIC in the marine environment. Thus, the proposed review will identify new eco-friendly MIC inhibitors and will assay their potential in future applications in the anti-corrosion industry.

Glycosylation and Lipidation Strategies: Approaches for Improving Antimicrobial Peptide Efficacy

Antimicrobial peptides (AMPs) have recently gained attention as a viable solution for combatting antibiotic resistance due to their numerous advantages, including their broad-spectrum activity, low propensity for inducing resistance, and low cytotoxicity. Unfortunately, their clinical application is limited due to their short half-life and susceptibility to proteolytic cleavage by serum proteases. Indeed, several chemical strategies, such as peptide cyclization, N-methylation, PEGylation, glycosylation, and lipidation, are widely used for overcoming these issues. This review describes how lipidation and glycosylation are commonly used to increase AMPs’ efficacy and engineer novel AMP-based delivery systems. The glycosylation of AMPs, which involves the conjugation of sugar moieties such as glucose and N-acetyl galactosamine, modulates their pharmacokinetic and pharmacodynamic properties, improves their antimicrobial activity, and reduces their interaction with mammalian cells, thereby increasing selectivity toward bacterial membranes. In the same way, lipidation of AMPs, which involves the covalent addition of fatty acids, has a significant impact on their therapeutic index by influencing their physicochemical properties and interaction with bacterial and mammalian membranes. This review highlights the possibility of using glycosylation and lipidation strategies to increase the efficacy and activity of conventional AMPs.

Temporins: Multifunctional Peptides from Frog Skin

Temporins are short peptides secreted by frogs from all over the world. They exert antimicrobial activity, mainly against Gram-positive bacteria, including resistant pathogens; recent studies highlight other possible applications of these peptides as anticancer or antiviral agents. This review is meant to describe the main features of temporins produced by different ranid genera. Due to the abundance of published papers, we focus on the most widely investigated peptides. We report studies on their mechanism of action and three-dimensional structure in model systems mimicking bacterial membranes or in the presence of cells. The design and the antimicrobial activity of peptide analogues is also described, with the aim of highlighting elements that are crucial to improve the bioactivity of peptides while reducing their toxicity. Finally, a short section is dedicated to the studies aimed at applying these peptides as drugs, to produce new antimicrobial materials or in other technological uses.

Structural parameters of nanoparticles affecting their toxicity for biomedical applications: a review

Rapidly growing interest in using nanoparticles (NPs) for biomedical applications has increased concerns about their safety and toxicity. In comparison with bulk materials, NPs are more chemically active and toxic due to the greater surface area and small size. Understanding the NPs' mechanism of toxicity, together with the factors influencing their behavior in biological environments, can help researchers to design NPs with reduced side effects and improved performance. After overviewing the classification and properties of NPs, this review article discusses their biomedical applications in molecular imaging and cell therapy, gene transfer, tissue engineering, targeted drug delivery, Anti-SARS-CoV-2 vaccines, cancer treatment, wound healing, and anti-bacterial applications. There are different mechanisms of toxicity of NPs, and their toxicity and behaviors depend on various factors, which are elaborated on in this article. More specifically, the mechanism of toxicity and their interactions with living components are discussed by considering the impact of different physiochemical parameters such as size, shape, structure, agglomeration state, surface charge, wettability, dose, and substance type. The toxicity of polymeric, silica-based, carbon-based, and metallic-based NPs (including plasmonic alloy NPs) have been considered separately.

Effect of antimicrobial peptide conjugated surgical sutures on multiple drug-resistant microorganisms

Surgical site infections are commonly encountered as a risk factor in clinics that increase the morbidity of a patient after a surgical operation. Surgical sutures are one of the leading factor for the formation of surgical site infections that induce bacterial colonization by their broad surface area. Current strategies to overcome with surgical site infections consist utilization of antibiotic agent coatings such as triclosan. However, the significant increase in antibiotic resistance majorly decreases their efficiency against recalcitrant pathogens such as; Pseudomonas aeruginosa and Staphylococcus aureus. Therefore, the development of a multi drug-resistant antimicrobial suture without any cytotoxic effect to combat surgical site infections is vital. Antimicrobial peptides are the first defense line which has a broad range of spectrum against Gram-positive, and Gram-negative bacteria and even viruses. In addition, antimicrobial peptides have a rapid killing mechanism which is enhanced by membrane disruption and inhibition of functional proteins in pathogens without the development of antimicrobial resistance. In the scope of the current study, the antimicrobial effect of antimicrobial peptide conjugated poly (glycolic acid-co-caprolactone) (PGCL) sutures were investigated against P. aeruginosa and methicillin-resistant S. aureus (MRSA) strains by using antimicrobial peptide sequences of KRFRIRVRV-NH₂, RWRWRWRW-NH₂ and their dual combination (1:1). In addition, in vitro wound scratch assays were performed to evaluate the effect of antimicrobial peptide conjugated sutures on keratinocyte cell lines. Our results indicated that antimicrobial peptide modified sutures could be a potential novel medical device to overcome surgical site infections by the superior acceleration of wound healing.

Recent Approaches for Downplaying Antibiotic Resistance: Molecular Mechanisms

Antimicrobial resistance (AMR) is a ubiquitous public health menace. AMR emergence causes complications in treating infections contributing to an upsurge in the mortality rate. The epidemic of AMR in sync with a high utilization rate of antimicrobial drugs signifies an alarming situation for the fleet recovery of both animals and humans. The emergence of resistant species calls for new treatments and therapeutics. Current records propose that health drug dependency, veterinary medicine, agricultural application, and vaccination reluctance are the primary etymology of AMR gene emergence and spread. Recently, several encouraging avenues have been presented to contest resistance, such as antivirulent therapy, passive immunization, antimicrobial peptides, vaccines, phage therapy, and botanical and liposomal nanoparticles. Most of these therapies are used as cutting-edge methodologies to downplay antibacterial drugs to subdue the resistance pressure, which is a featured motive of discussion in this review article. AMR can fade away through the potential use of current cutting-edge therapeutics, advancement in antimicrobial susceptibility testing, new diagnostic testing, prompt clinical response, and probing of new pharmacodynamic properties of antimicrobials. It also needs to promote future research on contemporary methods to maintain host homeostasis after infections caused by AMR. Referable to the microbial ability to break resistance, there is a great ultimatum for using not only appropriate and advanced antimicrobial drugs but also other neoteric diverse cutting-edge therapeutics.

Antimicrobial Peptide Octominin-Encapsulated Chitosan Nanoparticles Enhanced Antifungal and Antibacterial Activities

Antimicrobial peptides (AMPs) have become a key solution for controlling multi-drug-resistant (MDR) pathogens, and the nanoencapsulation of AMPs has been used as a strategy to overcome challenges, such as poor stability, adverse interactions, and toxicity. In previous studies, we have shown the potent antimicrobial activity of Octominin against Candida albicans and Acinetobacter baumannii. This study is focused on the nanoencapsulation of Octominin with chitosan (CS) and carboxymethyl chitosan (CMC) as a drug delivery system using the ionotropic gelation technique. Octominin-encapsulated CS nanoparticles (Octominin-CNPs) had an average diameter and zeta potential of 372.80 ± 2.31 nm and +51.23 ± 0.38 mV, respectively, while encapsulation efficiency and loading capacity were 96.49 and 40.20%, respectively. Furthermore, Octominin-CNPs showed an initial rapid and later sustained biphasic release profile, and up to 88.26 ± 3.26% of the total Octominin release until 96 h. Transmission electron microscopy data showed the irregular shape of the Octominin-CNPs with aggregations. In vitro and in vivo toxicity of Octominin-CNPs was significantly lower than the Octominin at higher concentrations. The antifungal and antibacterial activities of Octominin-CNPs were slightly higher than those of Octominin in both the time-kill kinetic and microbial viability assays against C. albicans and A. baumannii, respectively. Mode of action assessments of Octominin-CNPs revealed that morphological alterations, cell membrane permeability alterations, and reactive oxygen species generation were slightly higher than those of Octominin at the tested concentrations against both C. albicans and A. baumannii. In antibiofilm activity assays, Octominin-CNPs showed slightly higher biofilm inhibition and biofilm eradication activities compared to that of Octominin. In conclusion, Octominin was successfully encapsulated into CS, and Octominin-CNPs showed lower toxicity and greater antimicrobial activity against C. albicans and A. baumannii compared to Octominin.

An Overview of the Potentialities of Antimicrobial Peptides Derived from Natural Sources

Antimicrobial peptides (AMPs) are constituents of the innate immune system in every kind of living organism. They can act by disrupting the microbial membrane or without affecting membrane stability. Interest in these small peptides stems from the fear of antibiotics and the emergence of microorganisms resistant to antibiotics. Through membrane or metabolic disruption, they defend an organism against invading bacteria, viruses, protozoa, and fungi. High efficacy and specificity, low drug interaction and toxicity, thermostability, solubility in water, and biological diversity suggest their applications in food, medicine, agriculture, animal husbandry, and aquaculture. Nanocarriers can be used to protect, deliver, and improve their bioavailability effectiveness. High cost of production could limit their use. This review summarizes the natural sources, structures, modes of action, and applications of microbial peptides in the food and pharmaceutical industries. Any restrictions on AMPs' large-scale production are also taken into consideration.

Taming the Devil: Antimicrobial Peptides for Safer TB Therapeutics

Tuberculosis (TB) is a highly contagious infection with extensive mortality and morbidity. The rise of TB-superbugs (drug-resistant strains) with the increase of their resistance to conventional antibiotics has prompted a further search for new anti-mycobacterial agents. It is difficult to breach the barriers around TB bacteria, including mycolic cell wall, granuloma, biofilm and mucus, by conventional antibiotics in a short span of time. Hence, there is an essential need for molecules with an unconventional mode of action and structure that can efficiently break the barriers around mycobacterium. Antimicrobial peptides (AMP) are essential components of innate immunity having cationic and amphipathic characteristics. Lines of evidence show that AMPs have good myco-bactericidal and antibiofilm activity against normal as well as antibiotic-resistant TB bacteria. These peptides have shown direct killing of bacteria by membrane lysis and indirect killing by activation of innate immune response in host cells by interacting with the component of the bacterial membrane and intracellular targets through diverse mechanisms. Despite a good anti-mycobacterial activity, some undesirable characteristics are also associated with AMP, including hemolysis, cytotoxicity, susceptibility to proteolysis and poor pharmacokinetic profile, and hence only a few clinical studies have been conducted with these biomolecules. The design of new combinatorial therapies, including AMPs and particulate drug delivery systems, could be new potential alternatives to conventional antibiotics to fight MDR- and XDRTB. This review outlined the array of AMP roles in TB therapy, possible mechanisms of actions, activities, and current advances in pragmatic strategies to improve challenges accompanying the delivery of AMP for tuberculosis therapeutics.

Chitosan-based delivery system enhances antimicrobial activity of chlorhexidine

Infected chronic skin wounds and other skin infections are increasingly putting pressure on the health care providers and patients. The pressure is especially concerning due to the rise of antimicrobial resistance and biofilm-producing bacteria that further impair treatment success. Therefore, innovative strategies for wound healing and bacterial eradication are urgently needed; utilization of materials with inherent biological properties could offer a potential solution. Chitosan is one of the most frequently used polymers in delivery systems. This bioactive polymer is often regarded as an attractive constituent in delivery systems due to its inherent antimicrobial, anti-inflammatory, anti-oxidative, and wound healing properties. However, lipid-based vesicles and liposomes are generally considered more suitable as delivery systems for skin due to their ability to interact with the skin structure and provide prolonged release, protect the antimicrobial compound, and allow high local concentrations at the infected site. To take advantage of the beneficial attributes of the lipid-based vesicles and chitosan, these components can be combined into chitosan-containing liposomes or chitosomes and chitosan-coated liposomes. These systems have previously been investigated for use in wound therapy; however, their potential in infected wounds is not fully investigated. In this study, we aimed to investigate whether both the chitosan-containing and chitosan-coated liposomes tailored for infected wounds could improve the antimicrobial activity of the membrane-active antimicrobial chlorhexidine, while assuring both the anti-inflammatory activity and cell compatibility. Chlorhexidine was incorporated into three different vesicles, namely plain (chitosan-free), chitosan-containing and chitosan-coated liposomes that were optimized for skin wounds. Their release profile, antimicrobial activities, anti-inflammatory properties, and cell compatibility were assessed in vitro. The vesicles comprising chitosan demonstrated slower release rate of chlorhexidine and high cell compatibility. Additionally, the inflammatory responses in murine macrophages treated with these vesicles were reduced by about 60% compared to non-treated cells. Finally, liposomes containing both chitosan and chlorhexidine demonstrated the strongest antibacterial effect against Staphylococcus aureus. Both chitosan-containing and chitosan-coated liposomes comprising chlorhexidine could serve as excellent platforms for the delivery of membrane-active antimicrobials to infected wounds as confirmed by improved antimicrobial performance of chlorhexidine.

Encapsulation of Essential Oils in Nanocarriers for Active Food Packaging

Active packaging improves a packaging system's effectiveness by actively integrating additional components into the packaging material or the headspace around the packaging. Consumer demand and awareness have grown enough to replace chemical agents with natural active agents. Essential oils (EOs) are extensively distributed throughout nature but at low levels and sometimes with poor recovery yields, which poses an issue with their application in food. Due to the instability of EOs when added directly into a food product, they require encapsulation before being added to a packaging matrix such as liposomes, solid-lipid nanoparticles, nano-emulsions, cyclodextrins, and nanostructured lipid nano-carriers. This article is focused on the encapsulation of EOs in different types of nanocarriers. Nanocarriers can improve the efficiency of active substances by providing protection, stability, and controlled and targeted release. The advantages of the many types of nanocarriers that contain active substances that can be used to make antibacterial and antioxidant biopolymeric-based active packaging are discussed. A nanocarrier-encapsulated EO enables the controlled release of oil, stabilizing the packaging for a longer duration.

Genomewide Analysis and Biological Characterization of Cathelicidins with Potent Antimicrobial Activity and Low Cytotoxicity from Three Bat Species

Cathelicidins are potent antimicrobial peptides with broad spectrum antimicrobial activity in many vertebrates and an important component of the innate immune system. However, our understanding of the genetic variations and biological characteristics of bat cathelicidins is limited. In this study, we performed genome-level analysis of the antimicrobial peptide cathelicidins from seven bat species in the six families, listed 19 cathelicidin-like sequences, and showed that the number of functional cathelicidin genes differed among bat species. Based on the identified biochemical characteristics of bat cathelicidins, three cathelicidins, HA-CATH (from Hipposideros armiger), ML-CATH (from Myotis lucifugus), and PD-CATH (from Phyllostomus discolor), with clear antimicrobial signatures were chemically synthesized and evaluated antimicrobial activity. HA-CATH showed narrow-spectrum antibacterial activity against a panel of 12 reference bacteria, comprising 6 Gram-negative and 6 Gram-positive strains. However, ML-CATH and PD-CATH showed potent antibacterial activity against a broad spectrum of Gram-negative and Gram-positive bacteria with minimum inhibitory concentration (MIC) of 1 and 3 μg/mL, respectively, against Staphylococcus aureus. ML-CATH and PD-CATH also showed antifungal activities against Candida albicans and Cryptococcus cuniculi with MIC of 5 to 40 μg/mL, respectively, and 80% inhibition of the metabolism of Mucor hiemalis hyphae at 80 μg/mL, while displaying minimal cytotoxicity to HaCaT cells. Taken together, although the spectrum and efficacy of bat cathelicidins were species-dependent, the antimicrobial activity of ML-CATH and PD-CATH was comparable to that of other highly active cathelicidins in vertebrates while having negligible cytotoxicity to mammalian cells. ML-CATH and PD-CATH can be exploited as promising candidates for the development of antimicrobial therapeutics.

Nanobiotechnology with Therapeutically Relevant Macromolecules from Animal Venoms: Venoms, Toxins, and Antimicrobial Peptides

Some diseases of uncontrolled proliferation such as cancer, as well as infectious diseases, are the main cause of death in the world, and their causative agents have rapidly developed resistance to the various existing treatments, making them even more dangerous. Thereby, the discovery of new therapeutic agents is a challenge promoted by the World Health Organization (WHO). Biomacromolecules, isolated or synthesized from a natural template, have therapeutic properties which have not yet been fully studied, and represent an unexplored potential in the search for new drugs. These substances, starting from conglomerates of proteins and other substances such as animal venoms, or from minor substances such as bioactive peptides, help fight diseases or counteract harmful effects. The high effectiveness of these biomacromolecules makes them promising substances for obtaining new drugs; however, their low bioavailability or stability in biological systems is a challenge to be overcome in the coming years with the help of nanotechnology. The objective of this review article is to describe the relationship between the structure and function of biomacromolecules of animal origin that have applications already described using nanotechnology and targeted delivery.

Targeting foodborne pathogens via surface-functionalized nano-antimicrobials

The incorporation of antibiotics and bioactive compounds into non-toxic nanoparticles has been popularly used to produce effective antimicrobial nanocarriers against foodborne pathogens. These systems can protect antimicrobials against harsh environments, control their release, and increase their antimicrobial activities; however, their functions can be decreased by some major barriers. Intracellular localization of bacteria protects them from the host immune system and antimicrobial agents. Also, bacteria can cause constant infection by nestling in professional phagocytic cells. In the last years, surface functionalization of nanocarriers by passive and active modification methods has been applied for their protection against clearance from the blood, increasing both circulation time and uptake by target cells. For achieving this objective, different functional agents such as specifically targeted peptides internalize ligands, saccharide ligands, or even therapeutic molecules (e.g., antibodies or enzymes) are used. In this review, techniques for functionalizing the surface of antimicrobial-loaded nanocarriers have been described. This article offers a comprehensive review of the potential of functional nanoparticles to increase the performance of antimicrobials against foodborne pathogens through targeting delivery.

Melittin from Bee Venom Encapsulating Electrospun Fibers as a Potential Antimicrobial Wound Dressing Patches for Skin Infections

Skin infection compromises the body’s natural defenses. Several antibiotics are no longer effective owing to the evolution of antimicrobial-resistant (AMR) bacteria, hence, the constant development of novel antibacterial agents. Naturally occurring antibacterial agents may be potential candidates for AMR bacterial infection treatments; however, caution should be taken when administering such agents due to the high incidence of toxicity. A fibrous material system from a biocompatible polymer that could be used as a skin patch for skin infections treatment caused by AMR bacteria is proposed in this study. Bee venom’s active ingredient, melittin, was fabricated using electrospinning technology. Scanning electron microscopy showed that melittin-loaded fibers had smooth surfaces with no signs of beads or pores. The average diameter of this fibrous system was measured to be 1030 ± 160 nm, indicating its successful preparation. The melittin fibers’ drug loading and entrapment efficiency (EE%) were 49 ± 3 µg/mg and 84 ± 5%, respectively. This high EE% can be another successful preparatory criterion. An in vitro release study demonstrated that 40% of melittin was released after 5 min and achieved complete release after 120 min owing to the hydrophilic nature of the PVP polymer. A concentration of ≤10 µg/mL was shown to be safe for use on human dermal fibroblasts HFF-1 after 24-h exposure, while an antibacterial MIC study found that 5 μg/mL was the effective antimicrobial concentration for S. aureus, A. baumannii, E. coli and Candida albicans yeast. A melittin-loaded fibrous system demonstrated an antibacterial zone of inhibition equivalent to the control (melittin discs), suggesting its potential use as a wound dressing patch for skin infections.

Antimicrobial Activity Enhancers: Towards Smart Delivery of Antimicrobial Agents

The development of effective treatments against infectious diseases is an extensive and ongoing process due to the rapid adaptation of bacteria to antibiotic-based therapies. However, appropriately designed activity enhancers, including antibiotic delivery systems, can increase the effectiveness of current antibiotics, overcoming antimicrobial resistance and decreasing the chance of contributing to further bacterial resistance. The activity/delivery enhancers improve drug absorption, allow targeted antibiotic delivery, improve their tissue and biofilm penetration and reduce side effects. This review provides insights into various antibiotic activity enhancers, including polymer, lipid, and silver-based systems, designed to reduce the adverse effects of antibiotics and improve formulation stability and efficacy against multidrug-resistant bacteria.

Overcoming Multidrug Resistance of Antibiotics via Nanodelivery Systems

Antibiotic resistance has become a threat to microbial therapies nowadays. The conventional approaches possess several limitations to combat microbial infections. Therefore, to overcome such complications, novel drug delivery systems have gained pharmaceutical scientists’ interest. Significant findings have validated the effectiveness of novel drug delivery systems such as polymeric nanoparticles, liposomes, metallic nanoparticles, dendrimers, and lipid-based nanoparticles against severe microbial infections and combating antimicrobial resistance. This review article comprises the specific mechanism of antibiotic resistance development in bacteria. In addition, the manuscript incorporated the advanced nanotechnological approaches with their mechanisms, including interaction with the bacterial cell wall, inhibition of biofilm formations, activation of innate and adaptive host immune response, generation of reactive oxygen species, and induction of intracellular effect to fight against antibiotic resistance. A section of this article demonstrated the findings related to the development of delivery systems. Lastly, the role of microfluidics in fighting antimicrobial resistance has been discussed. Overall, this review article is an amalgamation of various strategies to study the role of novel approaches and their mechanism to fight against the resistance developed to the antimicrobial therapies.

Role of nanomaterials in deactivating multiple drug resistance efflux pumps - A review

The changes in lifestyle and living conditions have affected not only humans but also microorganisms. As man invents new drugs and therapies, pathogens alter themselves to survive and thrive. Multiple drug resistance (MDR) is the talk of the town for decades now. Many generations of medications have been termed useless as MDR rises among the infectious population. The surge in nanotechnology has brought a new hope in reducing this aspect of resistance in pathogens. It has been observed in several laboratory-based studies that the use of nanoparticles had a synergistic effect on the antibiotic being administered to the pathogen; several resistant strains scummed to the stress created by the nanoparticles and became susceptible to the drug. The major cause of resistance to date is the efflux system, which makes the latest generation of antibiotics ineffective without reaching the target site. If species-specific nanomaterials are used to control the activity of efflux pumps, it could revolutionize the field of medicine and make the previous generation resistant medications active once again. Therefore, the current study was devised to assess and review nanoparticles' role on efflux systems and discuss how specialized particles can be designed towards an infectious host's particular drug ejection systems.

Nanoencapsulated Lippia rotundifolia antimicrobial peptide: synthesis, characterization, antimicrobial activity, and cytotoxicity evaluations

Antimicrobial peptides (AMP) are promising novel antibiotics but exhibit low stability and can be toxic. The AMP encapsulation can be used to protect the drug and control its release rates. The Lr-AMP1f encapsulated into chitosan nanoparticle (NP) by ionic gelation method reached 90% efficiency. The results indicated that the hydrodynamic particle size of NPs increased from 196.1 ± 3.14 nm (free NP) to 228.1 ± 12.22 nm (nanoencapsulated Lr-AMP1f), while the atomic force microscope showed the spherical shape. The Zeta potential of the nanoencapsulated Lr-AMP1f was high (+ 35 mV). These AMP-loaded NPs exhibited stability for up to 21 days of storage. The minimum inhibitory concentration (MIC) of free Lr-AMP1f was 8 µg/mL for E. coli and S. epidermidis. However, the nanoencapsulated Lr-AMP1f produced a bacteriostatic effect against both bacteria at 8 µg/mL. The MIC of nanoencapsulated Lr-AMP1f was 16 µg/mL for E. coli and 32 for S. epidermidis. Nanoencapsulated Lr-AMP1f was nontoxic to HEK293 cells. Promisingly, chitosan NP can be used as a vehicle for the antibacterial application of new AMP (Lr-AMP1f).

The Expanded Role of Chitosan in Localized Antimicrobial Therapy

Chitosan is one of the most studied natural origin polymers for biomedical applications. This review focuses on the potential of chitosan in localized antimicrobial therapy to address the challenges of current rising antimicrobial resistance. Due to its mucoadhesiveness, chitosan offers the opportunity to prolong the formulation residence time at mucosal sites; its wound healing properties open possibilities to utilize chitosan as wound dressings with multitargeted activities and more. We provide an unbiased overview of the state-of-the-art chitosan-based delivery systems categorized by the administration site, addressing the site-related challenges and evaluating the representative formulations. Specifically, we offer an in-depth analysis of the current challenges of the chitosan-based novel delivery systems for skin and vaginal infections, including its formulations optimizations and limitations. A brief overview of chitosan's potential in treating ocular, buccal and dental, and nasal infections is included. We close the review with remarks on toxicity issues and remaining challenges and perspectives.

Current Advances in Lipid and Polymeric Antimicrobial Peptide Delivery Systems and Coatings for the Prevention and Treatment of Bacterial Infections

Bacterial infections constitute a threat to public health as antibiotics are becoming less effective due to the emergence of antimicrobial resistant strains and biofilm and persister formation. Antimicrobial peptides (AMPs) are considered excellent alternatives to antibiotics; however, they suffer from limitations related to their peptidic nature and possible toxicity. The present review critically evaluates the chemical characteristics and antibacterial effects of lipid and polymeric AMP delivery systems and coatings that offer the promise of enhancing the efficacy of AMPs, reducing their limitations and prolonging their half-life. Unfortunately, the antibacterial activities of these systems and coatings have mainly been evaluated in vitro against planktonic bacteria in less biologically relevant conditions, with only some studies focusing on the antibiofilm activities of the formulated AMPs and on the antibacterial effects in animal models. Further improvements of lipid and polymeric AMP delivery systems and coatings may involve the functionalization of these systems to better target the infections and an analysis of the antibacterial activities in biologically relevant environments. Based on the available data we proposed which polymeric AMP delivery system or coatings could be profitable for the treatment of the different hard-to-treat infections, such as bloodstream infections and catheter- or implant-related infections.

Host Defense Peptides: Dual Antimicrobial and Immunomodulatory Action

The rapid rise of multidrug-resistant (MDR) bacteria has once again caused bacterial infections to become a global health concern. Antimicrobial peptides (AMPs), also known as host defense peptides (HDPs), offer a viable solution to these pathogens due to their diverse mechanisms of actions, which include direct killing as well as immunomodulatory properties (e.g., anti-inflammatory activity). HDPs may hence provide a more robust treatment of bacterial infections. In this review, the advent of and the mechanisms that lead to antibiotic resistance will be described. HDP mechanisms of antibacterial and immunomodulatory action will be presented, with specific examples of how the HDP aurein 2.2 and a few of its derivatives, namely peptide 73 and cG4L73, function. Finally, resistance that may arise from a broader use of HDPs in a clinical setting and methods to improve biocompatibility will be briefly discussed.

Biogenic and characterizations of new silver nanoparticles stabilized with indole acetic acid derived from Azospirillum brasilense MMGH-SADAT1, their bioactivity, and histopathological assessment in rats

An Egyptian rhizobacterium Azospirillum sp. isolated from Sadat city was able to produce indole acetic acid (IAA) up to (30.59 µg/ml). The isolate was identified biochemically and by 16S rRNA sequencing which showed 99.9% similarity to Azospirillum brasilense. The new isolate has been registered in Genbank with accession number MH179119.1. Extracted IAA was used as reducing or stabilizing agent of sliver nanoparticles (AgNPs). Successful fabrication of biogenic IAA-AgNPs was confirmed by Fourier Transform Infrared Spectrophotometer (FTIR) analysis of IAA which showed absorbance peak at 3434.78 cm^-1 due to the N-H stretch of primary amines. Highly resolution Transmission Electron Microscopy (HR-TEM) showed AgNPs coating or capping with IAA in spherical shaped with size ranged from 6.01 to 44.02 nm. Energy dispersive X-ray (EDX) analysis revealed that Ag⁺ ions were attached to the surface of IAA-AgNPs particles. HR-TEM examination showed cell wall damage of Citrobacter freundii cells after exposure to IAA-AgNPs leading to cell death. In vivo results showed that C. freundii infection of rats induced significant increase in liver and kidney functions and deleterious histopathological alteration in rat's tissues. However, treatment by extracted IAA and IAA-AgNPs could normalize the biochemical and histopathological alterations occurred in infected rats. This is the first study to prove that IAA extracted from Azospirillum brasilense is a hopeful capping agent for NPs which has potential to protect against pathogenic infections, nontoxic and/or safe on rat's metabolisms.