Antibacterial activities of inorganic agents on six bacteria associated with oral infections by two susceptibility tests

Bifunctional Cu-incorporated carbon nanospheres via in-situ complexation strategy as efficient toluene adsorbents and antibacterial agents

Carbon adsorbents have been widely used to remove indoor volatile organic compounds (VOCs), however, the proliferation of bacteria on the carbon adsorbents may deteriorate the indoor air quality and thus pose a serious threat to human health. Herein, we report the synthesis of antibacterial porous carbon spheres (carbonized aminophenol-formaldehyde resin, CAF) with well-dispersed Cu species via an in situ incorporation of Cu2+ during the polymerization of 3-aminophenol-formaldehyde resin followed by a thermal carbonization and reduction process. Compared with CAF, the Cu/CAF-x nanocomposites with Cu loading show a much higher specific surface area (>700 m2 g-1vs. 569 m2 g-1 for CAF). In addition, the pore size of Cu/CAF-x is ranging from 0.7 to 1.68 nm, which is exactly conducive to adsorb the toluene molecules. As a result, the toluene adsorption capacity is improved from 123.50 mg g-1 for CAF to >170 mg g-1 for Cu/CAF-x. More importantly, such adsorbents possess excellent antibacterial performance, the Cu/CAF-10 (10 wt% of Cu loading) with a concentration of 50 μg mL-1 can completely kill the E. coli within 30 min. Our work paves the way to the development of bifunctional adsorbents with both efficient VOCs adsorption and excellent antibacterial performance.

Electrodeposited Zinc Coatings for Biomedical Application: Morphology, Corrosion and Biological Behaviour

The improvement of biodegradable metals is currently an active and promising research area for their capabilities in implant manufacturing. However, controlling their degradation rate once their surface is in contact with the physiological media is a challenge. Surface treatments are in the way of addressing the improvement of this control. Zinc is a biocompatible metal present in the human body as well as a metal widely used in coatings to prevent corrosion, due to its well-known metal protective action. These two outstanding characteristics make zinc coating worthy of consideration to improve the degradation behaviour of implants. Electrodeposition is one of the most practical and common technologies to create protective zinc coatings on metals. This article aims to review the effect of the different parameters involved in the electrochemical process on the topography and corrosion characteristics of the zinc coating. However, certainly, it also provides an actual and comprehensive description of the state-of-the-art of the use of electrodeposited zinc for biomedical applications, focusing on their capacity to protect against bacterial colonization and to allow cell adhesion and proliferation.

Bioinspired Synthesis of Zinc Molybdate Nanoparticles: An Efficient Material for Growth Inhibition of Escherichia coli, Staphylococcus aureus, and Dye Remediation

Zinc molybdate nanoparticles with molybdate are synthesized through green method with different salt precursors using Moringa oleifera leaf extract. Those nanoparticles had structural, vibrational, and morphological properties, which were determined by X-ray diffraction (XRD). The crystalline size of synthesized zinc molybdate was 24.9 nm. Fourier transform infrared (FTIR) spectroscopy and field emission scanning electron microscopy (FE-SEM) clearly showed the attachment of molybdate with ZnO. The synthesized nanomaterial was also characterized through UV-visible spectroscopy which had 4.40 eV band gap energy. Those nanoparticles were also characterized via thermogravimetric analysis (TGA-DTA) and photoluminance spectroscopy (PL). ZnMoO4 had photocatalytic property via methylene blue dye. After 190 minutes, the dye changed to colourless from blue colour. The degradation efficiency was around 92.8%. It also showed their antibacterial effect via Escherichia coli and Staphylococcusaureus bacterial strains. In the presence of light and air, nanoparticles of ZnMoO4 inhibit the growth of cells of E. coli and S. aureus bacterial strains because of ROS (reactive oxygen species) generation. Because of the formation of singlet oxygen (O2∗-), hydrogen oxide radical (-OH∗), and hydrogen peroxide (H2O2), ZnMoO4 showed photodegradation reaction against aq. solution of methylene blue dye at 6 pH with constant time interval. With time, the activity of ZnMoO4 also decreased because of the generation of a layer of hydrogen oxide (-OH) on nanomaterial surface, which could be washed with ethanol and distilled water. After drying, the catalytic Zinc molybdate nanoparticles could be reused again in the next catalytic reaction.

Recent advances of antibacterial starch-based materials

Starch has attracted a lot of attention because it is biodegradable, renewable, nontoxic and low cost. By adding antibacterial substances to starch, starch-based materials have antibacterial properties. The composite with other materials can improve the comprehensive performance of starch-based materials, thus broadening the application field of the material. In this paper, we focus on antibacterial starch-based materials and review their preparation and applications. It was found that antibacterial starch-based materials were most widely used in packaging, followed by medicine, and the research on smart starch-based materials was relatively less. This review may provide some reference value for subsequent studies of starch-based materials.

Exploring the Co-Crystallization of Kojic Acid with Silver(I), Copper(II), Zinc(II), and Gallium(III) for Potential Antibacterial Applications

Co-crystallization of kojic acid (HKA) with silver(I), copper(II), zinc(II), or gallium(III) salts yielded three 1D coordination polymers and one 0D complex in which kojic acid was present as a neutral or anionic terminal or bridging ligand. All reactions were conducted mechanochemically via ball milling and manual grinding, or via slurry. All solids were fully characterized via single-crystal and/or powder X-ray diffraction. As kojic acid is a mild antimicrobial compound that is widely used in cosmetics, and the metal cations possess antibacterial properties, their combinations were tested for potential antibacterial applications. The minimal inhibition concentrations (MICs) and minimal biocidal concentrations (MBCs) for all compounds were measured against standard strains of the bacteria P. aeruginosa, S. aureus, and E. coli. All compounds exerted appreciable antimicrobial activity in the order of silver, zinc, copper, and gallium complexes.

Antimicrobial Agents Based on Metal Complexes: Present Situation and Future Prospects

The rise in antimicrobial resistance is a cause of serious concern since the ages. Therefore, a dire need to explore new antimicrobial entities that can combat against the increasing threat of antibiotic resistance is realized. Studies have shown that the activity of the strongest antibiotics has reduced drastically against many microbes such as microfungi and bacteria (Gram-positive and Gram-negative). A ray of hope, however, was witnessed in early 1940s with the development of new drug discovery and use of metal complexes as antibiotics. Many new metal-based drugs were developed from the metal complexes which are potentially active against a number of ailments such as cancer, malaria, and neurodegenerative diseases. Therefore, this review is an attempt to describe the present scenario and future development of metal complexes as antibiotics against wide array of microbes.

Innovative Investigation of Zinc Oxide Nanoparticles Used in Dentistry

Dental caries is a major lifestyle concern as dental components affect the face of an individual. The issue of tooth decay occurs in every age group throughout the globe. Researchers are probing incipient implements and techniques to develop filling agents for decayed teeth. Zinc oxide (ZnO) powder is utilized mostly as a filling agent. Nanotechnology enhanced the efficiency of compounds of metal oxides utilized for dental caries. The present study aims to investigate the properties of ZnO nanoparticles (NPs) synthesized chemically (using ZnCl2 and NaOH) as well as biologically (using aqueous leaf extract of Murraya paniculata). The XRD patterns confirm that ZnO NPs have a hexagonal crystalline structure with particle sizes of 47 nm and 55 nm for chemically and biologically synthesized NPs, respectively. The FE-SEM data confirm the nanorod and spherical/cubical shape morphologies for the chemically and biologically synthesized ZnO NPs, respectively. FTIR data show the peaks between 4000 and 450 cm−1 of the functional groups of –OH, C-O, –C-H-, and Zn-O bonds. The UV–Vis absorption study indicates a peak around 370 nm and a hump around 360 nm corresponding to the chemically and biologically synthesized ZnO NPs, respectively. An antibacterial bioassay was performed and compared with commercially available ZnO bulk powder against tooth decaying pathogens, viz., Streptococcus mutans, Staphylococcus aureus, E. coli, and Lactobacillus fermentum, and found that both ZnO NPs had results closer to those of the standard drug (rifampicin). Thus, the synthesized ZnO NPs may be utilized as nano-drugs for the application of tooth decaying filling agents. Even biologically synthesized ZnO NPs may be considered more environmentally friendly and less toxic to human health concerns.

Dental resin composites with improved antibacterial and mineralization properties via incorporating zinc/strontium-doped hydroxyapatite as functional fillers

This study intends to improve the antibacterial and mineralization performance of photocurable dental resin composites (DRCs) to reduce the possibility of repair failure caused by secondary caries. To the end, functionalized hydroxyapatite (HAp), including Zn-doped (Zn/HAp) and Sr-doped HAp (Sr/HAp), were added into the bisphenol A glycidyl methacrylate and triethylene glycol dimethacrylate mixture, providing the DRCs with antibacterial and mineralization capacity, respectively. By controlling the total amount of inorganic filler at 70 wt%, these HAp powders were introduced into the resin matrix with barium glass powder (BaGP), while the ratios of HAp to aGP varied from 0:70 to 8:62. And the 8 wt% of HAp could be pure HAp, Zn/HAp, Sr/HAp, or Zn/HAp +Sr/HAp in different ratios (i.e. 2:6, 4:4, 6:2). Though the fillers varied, the obtained DRCs displayed similar micro-morphology, flexural strength (∼110 MPa) and modulus (∼7 GPa), and Vickers hardness (∼65). When the doping amounts of Sr²⁺/Zn²⁺reached 15 mol% of Ca²⁺in the Sr/HAp and Zn/HAp, the DRCs displayed a high antibacterial activity by killing ∼95%Staphylococcus aureus, and induced rich mineral deposition on surface in simulated body fluid. The incorporation of the Zn/HAp and Sr/HAp into the DRCs did not cause significant cytotoxicity, with L929 fibroblasts remaining >99% viability as cultured in extracts made from the DRCs. Therein, the DRC preparations containing both Zn/HAp and Sr/HAp have achieved improvements in both the biomineralization and antibacterial performance, as well as, having sufficient mechanical properties and excellent biocompatibility for dental restoration.

Antibacterial Activity of Electrodeposited Copper and Zinc on Metal Injection Molded (MIM) Micropatterned WC-CO Hard Metals

Antibacterial activity of electrodeposited copper and zinc both on flat and micropatterned hard metal tungsten carbide-cobalt (WC-Co) specimens was studied. Tribological wear was applied on electrodeposited specimens: coatings were completely removed from flat surfaces whereas only top of the micropillars was exposed to wear for the micropatterned specimens protecting the functional metal coating in between the micropillars. The growth of Staphylococcus aureus (S. aureus) Gram-positive bacterial species was studied on the specimens using a touch test mimicking bacterial transfer from the surfaces. Copper coated specimens prevented bacterial growth completely independent of wear or surface structure, i.e., even residual traces of copper were sufficient to prevent bacterial growth. Zinc significantly suppressed the bacterial growth both on flat and micropatterned specimens. However, adhesion of zinc was low resulting in an easy removal from the surface by wear. The micropatterned zinc specimens showed antibacterial activity as electrodeposited zinc remained intact on the sample surface between the micropillars. This was sufficient to suppress the growth of S. aureus. On the contrary, the flat zinc coated surfaces did not show any antibacterial activity after wear. Our results show that micropatterned hard metal specimens can be used to preserve antibacterial activity under tribological wear.

From Himba indigenous knowledge to engineered Fe2O3 UV-blocking green nanocosmetics

This contribution reports on the physical properties of the natural Namibian red Ochre used by the Himba Community in a form of a formulation, so called Otjize as a skin protective and beauty cream. The morphological and crystallographic studies of this red ochre validated its nano-scaled dominating phase of rhombohedral α-Fe₂O₃ nanocrystals with an additional hydrolized oxide component in a form of γ-FeOOH. The optical investigations showed that such a red ochre exhibits an exceptional UV filtration and a significant IR reflectivity substantiating its effectiveness as an effective UV-blocking & solar heat IR reflector in support of the low skin cancer rate within the Namibian Himba community. In addition, such nanocrystals exhibited a non-negligible antibacterial response against E. Coli & S. Aurus. This study seems confirming the effectiveness of the indigenous Otjize as an effective skin UV protection cream with a sound antimicrobial efficacy against e-Coli & S-Aurus.

Metal Oxide Nanoparticles and Nanotubes: Ultrasmall Nanostructures to Engineer Antibacterial and Improved Dental Adhesives and Composites

Advances in nanotechnology have unlocked exclusive and relevant capabilities that are being applied to develop new dental restorative materials. Metal oxide nanoparticles and nanotubes perform functions relevant to a range of dental purposes beyond the traditional role of filler reinforcement-they can release ions from their inorganic compounds damaging oral pathogens, deliver calcium phosphate compounds, provide contrast during imaging, protect dental tissues during a bacterial acid attack, and improve the mineral content of the bonding interface. These capabilities make metal oxide nanoparticles and nanotubes useful for dental adhesives and composites, as these materials are the most used restorative materials in daily dental practice for tooth restorations. Secondary caries and material fractures have been recognized as the most common routes for the failure of composite restorations and bonding interface in the clinical setting. This review covers the significant capabilities of metal oxide nanoparticles and nanotubes incorporated into dental adhesives and composites, focusing on the novel benefits of antibacterial properties and how they relate to their translational applications in restorative dentistry. We pay close attention to how the development of contemporary antibacterial dental materials requires extensive interdisciplinary collaboration to accomplish particular and complex biological tasks to tackle secondary caries. We complement our discussion of dental adhesives and composites containing metal oxide nanoparticles and nanotubes with considerations needed for clinical application. We anticipate that readers will gain a complete picture of the expansive possibilities of using metal oxide nanoparticles and nanotubes to develop new dental materials and inspire further interdisciplinary development in this area.

Enhanced Optical and Antibacterial Activity of Hydrothermally Synthesized Cobalt-Doped Zinc Oxide Cylindrical Microcrystals

Cobalt (Co) doped zinc oxide (ZnO) microcrystals (MCs) are prepared by using the hydrothermal method from the precursor's mixture of zinc chloride (ZnCl2), cobalt-II chloride hexahydrate (CoCl2·6H2O), and potassium hydroxide (KOH). The smooth round cylindrical morphologies of the synthesized microcrystals of Co-doped ZnO show an increase in absorption with the cobalt doping. The antibacterial activity of the as-obtained Co-doped ZnO-MCs was tested against the bacterial strains of gram-negative (Escherichia coli, Klebsiella pneumonia) and gram-positive bacteria (Staphylococcus aureus, Streptococcus pyogenes) via the agar well diffusion method. The zones of inhibition (ZOI) for Co-doped ZnO-MCs against E. coli and K. pneumoniae were found to be 17 and 19 mm, and 15 and 16 mm against S. Aureus and S. pyogenes, respectively. The prepared Co-doped ZnO-MCs were thus established as a probable antibacterial agent against gram-negative bacterial strains.

A review: Pharmacological aspects of metal based 1,2,4-triazole derived Schiff bases

Clinical reports have highlighted the radical increase of antibiotic resistance. As a result, multidrug resistance has emerged as a serious threat to human health. Many organic compounds commonly used as drugs in the past, no longer have pure organic mode of action rather need bio-transformation or more activation. Bulk of research has shown that they need trace amount of metal ions incorporated within the chemistry of bioactive molecules for enhancement of their potentiality to fight aggressively against resistance. The deficiency of some metal ions can also be responsible for many diseases like growth retardation, pernicious anemia and heart diseases in infants. To overcome these problems, there is a need to introduce novel strategies which have new mechanism of action along with significant spectrum of biological activity, enhanced safety and efficacy. Bioinorganic compounds have played imperative role in developing the new strategy in the form of "Metal Based Drugs". In current years there have been momentous rise of interest in the application of metal based Schiff base compounds to treat various diseases which are difficult to be treated with conventional methodologies. The unique properties of metal chelates acting as an intermediate between conventional organic and inorganic compounds provided innovative opportunities in the field of pharmaceutical chemistry. In this review, we have exclusively focused on the search of metal based 1,2,4-triazole derived Schiff base compounds (synthesized, reported and reviewed in the past ten years) that possess various biological activities such as antifungal, antibacterial, antioxidant, antidiabetic, anthelmintic, anticancer, antiproliferative, cytotoxic and DNA-intercalation activity.

Potential therapeutic and pharmacological strategies for SARS-CoV2

BACKGROUND

At the end of 2019, the new Coronavirus disease 2019 (COVID-19) strain causing severe acute respiratory syndrome swept the world. From November 2019 till February 2021, this virus infected nearly 104 million, with more than two million deaths and about 25 million active cases. This has prompted scientists to discover effective drugs to combat this pandemic.

AREA COVERED

Drug repurposing is the magic bullet for treating severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). Therefore, several drugs have been investigated in silico, in vitro, as well as through human trials such as anti-SARS-CoV2 agents, or to prevent the complications resulting from the virus. In this review, the mechanisms of action of different therapeutic strategies are summarized. According to the WHO, different classes of drugs can be used, including anti-malarial, antiviral, anti-inflammatory, and anti-coagulant drugs, as well as angiotensin-converting enzyme inhibitors, antibiotics, vitamins, zinc, neutralizing antibodies, and convalescent plasma therapy. Recently, there are some vaccines which are approved against SARS-CoV2.

EXPERT OPINION

A complete understanding of the structure and function of all viral proteins that play a fundamental role in viral infection, which contribute to the therapeutic intervention and the development of vaccine in order to reduce the mortality rate.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s40005-021-00520-4.

Utilization of induction furnace steel slag based iron oxide nanocomposites for antibacterial studies

Metals and metal oxide-based nanocomposites play a significant role over the control of microbes. In this study, antibacterial activity of iron oxide (Fe2O3) nanocomposites based on induction furnace (IF) steel slag has been carried out. IF steel slag is an industrial by-product generated from secondary steel manufacturing process and has various metal oxides which includes Al2O3 (7.89%), MnO (5.06), CaO (1.49%) and specifically Fe2O3 (14.30%) in higher content along with metalloid SiO2 (66.42). Antibacterial activity of iron oxide nanocomposites has been revealed on bacterial species such as Micrococcus luteus, Bacillus subtilis and Staphylococcus aureus. Micrococcus luteus has undergone maximum zone of inhibition (ZOI) of 12 mm for 10 mg/mL concentration of steel slag iron oxide nanocomposite. Growth inhibitory kinetics of bacterial species has been studied using ELISA microplate reader at 660 nm by varying the concentration of steel slag iron oxide nanocomposites. The results illustrate that IF steel slag is a potential material and can be utilized in building materials to increase the resistance against biodeterioration.

Graphic abstract

Antibacterial activity of an NIR-induced Zn ion release film

Photothermal therapy originated from using gold nanorods (GNRs) and near-infrared (NIR) irradiation has been widely used in the antibacterial field. Zn element exhibits antimicrobial activity against various bacterial and fungal strains. In this study, a bilayer film, consisting of GNRs as the inner layer and a polydopamine layer containing Zn element (PDA@Zn) as the outer layer, was deposited on the Ti surface. The results testified that all the GNR-modified surfaces had the same photothermal conversion efficiency. The Ti surface modified with GNR and PDA@Zn layers had better antibacterial activity against E. coli and S. aureus due to the GNR-induced photothermal effect and the antibacterial Zn element. Moreover, the accelerated release of Zn ions from the PDA@Zn layer was attributed to the GNR-induced high temperature under the NIR irradiation, which caused the concentration of Zn ions to be high enough to kill the surrounding bacteria. This study illustrates that a composite surface possessing both the contact and heat-responsive antibacterial property was constructed on titanium for potential clinical applications.

Evaluation of New Antimicrobial Materials Incorporating Ethyl Lauroyl Arginate or Silver into Different Matrices, and Their Safety in Use as Potential Packaging

A big challenge for today’s industry is antimicrobial preservation and the safety of food. An effective solution to this problem can be a modern invention such as antimicrobial packaging. In the presented research the antimicrobial activity of two new active films incorporating silver, as IONPURE IPL, and ethyl lauroyl arginate (LAE) were evaluated, by employing a low-density polyethylene (LDPE) matrix and a biofilm material, respectively. Additionally, LAE was also incorporated into polystyrene (PS) pads by two different methods: by spraying and by immersion of the PS pads into an aqueous LAE solution. LDPE films containing silver did not show any antimicrobial activity against Escherichia coli and Aspergillus flavus, whereas the biofilm containing LAE reduced the growth of Salmonella enterica but did not inhibit Aspergillus flavus. The active PS pads, both sprayed and immersed in LAE solution, also showed antimicrobial activity, causing a reduction of 99.99% of Pseudomonas putida growth. Thermal treatment at 180 °C for 6 and 15 min did not modify the antimicrobial activity of LAE against Salmonella enterica. Moreover, inductively coupled plasma-mass spectrometry (ICP-MS) analysis was performed to check the migration of silver from developed material intended for food packaging applications into food simulant.

Antibacterial activity and reinforcing effect of SiO2–ZnO complex cluster fillers for dental resin composites

The regular-shaped SiO₂-ZnO complex clusters constructed by spray-draying technology can enhance antibacterial activity while maintaining the mechanical and aesthetic properties of dental resin composites.

New Antimicrobial Strategies Based on Metal Complexes

Traditional organic antimicrobials mainly act on specific biochemical processes such as replication, transcription and translation. However, the emergence and wide spread of microbial resistance is a growing threat for human beings. Therefore, it is highly necessary to design strategies for the development of new drugs in order to target multiple cellular processes that should improve their efficiency against several microorganisms, including bacteria, viruses or fungi. The present review is focused on recent advances and findings of new antimicrobial strategies based on metal complexes. Recent studies indicate that some metal ions cause different types of damages to microbial cells as a result of membrane degradation, protein dysfunction and oxidative stress. These unique modes of action, combined with the wide range of three-dimensional geometries that metal complexes can adopt, make them suitable for the development of new antimicrobial drugs.

Polymeric Nanoparticles of Pistacia lentiscus var. chia Essential Oil for Cutaneous Applications

Polymeric nanoparticles (NPs) encapsulating Pistacia lentiscus L. var. chia essential oil (EO) were prepared by a solvent evaporation method, in order to obtain a novel carrier for administration on the skin. The specific EO exhibits antimicrobial and anti-inflammatory properties thus stimulating considerable interest as a novel agent for the treatment of minor skin inflammations. The incorporation into nanoparticles could overcome the administration limitations that inserts the nature of the EO. Nanoparticles were prepared, utilizing poly(lactic acid) (PLA) as shell material, due to its biocompatibility and biodegradability, while the influence of surfactant type on NPs properties was examined. Two surfactants were selected, namely poly(vinyl alcohol) (PVA) and lecithin (LEC) and NPs' physicochemical characteristics i.e. size, polydispersity index (PdI) and ζ-potential were determined, not indicating significant differences (p > 0.05) between PLA/PVA-NPs (239.9 nm, 0.081, -29.1 mV) and PLA/LEC-NPs (286.1 nm, 0.167, -34.5 mV). However, encapsulation efficiency (%EE) measured by GC-MS, was clearly higher for PLA/PVA-NPs than PLA/LEC-NPs (37.45% vs. 9.15%, respectively). Moreover PLA/PVA-NPs remained stable over a period of 60 days. The in vitro release study indicated gradual release of the EO from PLA/PVA-NPs and more immediate from PLA/LEC-NPs. The above findings, in addition to the SEM images of the particles propose a potential structure of nanocapsules for PLA/PVA-NPs, where shell material is mainly consisted of PLA, enclosing the EO in the core. However, this does not seem to be the case for PLA/LEC-NPs, as the results indicated low EO content, rapid release and a considerable percentage of humidity detected by SEM. Furthermore, the Minimum Inhibitory Concentration (MIC) of the EO was determined against Escherichia coli and Bacillus subtilis, while NPs, however did not exhibit considerable activity in the concentration range applied. In conclusion, the surfactant selection may modify the release of EO incorporated in NPs for topical application allowing its action without interfering to the physiological skin microbiota.

Antibacterial Activity of a Novel Biocomposite Chitosan/Graphite Based on Zinc-Grafted Mesoporous Silica Nanoparticles

INTRODUCTION

A novel biocomposite chitosan/graphite based on zinc-grafted mesoporous silica nanoparticles (CGZM-bio) was synthesized and the antibacterial activities of this compound along with that of Zn-MSN nanoparticles were investigated.

METHODS

The CGZM-bio biocomposite was synthesized using sol-gel and post-synthesis method under UV radiation. The characterizations of the samples were carried out using FTIR, XRD, SEM, and nitrogen adsorption and desorption. The antibacterial activity was carried out against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) after 18 h at 310 K.

RESULTS

The suspension samples of the Zn-MSN and CGZM-bio (2-100 µg.mL-1) presented antibacterial activities against S. aureus and E. coli. The minimum inhibitory concentration (MIC) values against E. coli for the Zn-MSN and CGZM-bio samples were 10 and 5 µg.mL-1, respectively, while the MIC against S. aureus for both nanomaterials was 10 µg.mL-1.

DISCUSSION

The antibacterial activities of these materials are due to the generation of radical oxygen species such as •OH, H2O2, and O2 2- during the UV radiation via the generation of the electron-hole pairs which in turn damage the bacteria cells. These nanomaterials may be used in biomedical devices as antibacterial agents.

Nanoparticles as Anti-Microbial, Anti-Inflammatory, and Remineralizing Agents in Oral Care Cosmetics: A Review of the Current Situation

Many investigations have pointed out widespread use of medical nanosystems in various domains of dentistry such as prevention, prognosis, care, tissue regeneration, and restoration. The progress of oral medicine nanosystems for individual prophylaxis is significant for ensuring bacterial symbiosis and high-quality oral health. Nanomaterials in oral cosmetics are used in toothpaste and other mouthwash to improve oral healthcare performance. These processes cover nanoparticles and nanoparticle-based materials, especially domains of application related to biofilm management in cariology and periodontology. Likewise, nanoparticles have been integrated in diverse cosmetic produces for the care of enamel remineralization and dental hypersensitivity. This review summarizes the indications and applications of several widely employed nanoparticles in oral cosmetics, and describes the potential clinical implementation of nanoparticles as anti-microbial, anti-inflammatory, and remineralizing agents in the prevention of dental caries, hypersensitivity, and periodontitis.

C, N dual-doped ZnO nanofoams: a potential antimicrobial agent, an efficient visible light photocatalyst and SXAS studies

It is crucial to develop an environmentally friendly and low-cost method to treat industrial effluent that contains soluble dyes and microbes. Most of the photocatalysts have been studied using an external light source that increases the cost of the purification process of effluent. This study focuses on developing efficient solar photocatalytic nanofoams. The controlled growth of ZnO nanofoams (CNZ nanofoams) in a simple method of thermal oxidation using a soft template is reported. Prepared nanofoams are characterized using X-ray diffraction, scanning electon microscopy and synchrotron soft X-ray absorption spectroscopy. By photocatalysis studies under direct sunlight it was found that within 120 min CNZ nanofoams degraded 99% of the dye. In addition, antimicrobial studies of multi-drug-resistant E. Fergusonii isolated from wastewater was carried out. These antimicrobial results showed a good inhibition zone, indicating that prepared nanofoams are both an effective solar photocatalyst and an antimicrobial agent.

Antimicrobial materials properties based on ion-exchange 4A zeolite derivatives

Zeolites are nanoporous alumina silicates in a framework with cations, exhibiting ion-exchange properties with metal ions making them possible antimicrobial materials. The aim of this study was to evaluate the antimicrobial activity of ion-exchanged zeolites and the toxic potential of these materials. Zeolite-Co2+ and Li+ exhibited the most effective inhibition on Staphylococcus aureus growth than in other microorganisms (Escherichia coli and Pseudomonas aeroginosa) in low concentrations. Zeolite-Cu2+ presented higher zone of inhibition when tested against Candida albicans, while Zeolite-Zn2+ showed similar effectiveness among all the microorganisms. When ion-exchanged zeolites were used in effective concentrations to achieve antimicrobial activity, no alterations against bioindicators organisms as Artemia sp. and L. sativa were found and, in addition, they have non-significant result in terms of DNA cleavage activity. Zeolites have advantage of releasing slowly the metals loaded and this characteristic can to be considered promising as potential antimicrobial materials in concentrations safe for use.

Preparation of Chitosan/Corn Starch/Cinnamaldehyde Films for Strawberry Preservation

In this study, the casting method was used to make chitosan (CS)/corn starch/cinnamaldehyde film, and the preservation performance of the film was examined. The results showed that the tensile strength of the film can reach to 31.24 ± 0.22 MPa when the mass ratios of CS, corn starch, and glycerin were 2.5%, 7%, and 0.5% respectively. The addition of cinnamaldehyde made the films have great inhibitory effect on Botrytis cinerea, Rhizopus, and Escherichia coli. In particular, the film had a significant fresh-keeping effect on strawberries, which reduced the loss of nutritional value, when aiming at soluble solids, titratable acid value, weight loss rate, and other indexes of strawberries. Thus, the films can slow down the physiological changes of strawberries and extend their shelf life to 11 days. Therefore, this work demonstrates the noteworthy potential of these novel films, incorporating natural antimicrobial compounds as innovative solutions to be used in active food packaging to extend the shelf-life of food products.

Simonkolleite Coating on Poly(Amino Acids) to Improve Osteogenesis and Suppress Osteoclast Formation in Vitro

Zinc can enhance osteoblastic bone formation and stimulate osteogenic differentiation, suppress the differentiation of osteoclast precursor cells into osteoclasts, and inhibit pathogenic bacterial growth in a dose-dependent manner. In this study, simonkolleite, as a novel zinc resource, was coated on poly (amino acids) (PAA) via suspending PAA powder in different concentrations of zinc chloride (ZnCl₂) solution, and the simonkolleite-coated PAA (Zn–PAA) was characterized by SEM, XRD, FT-IR and XPS. Zinc ions were continuously released from the coating, and the release behavior was dependent on both the concentration of the ZnCl₂ immersing solution and the type of soak solutions (SBF, PBS and DMEM). The Zn–PAA was cultured with mouse bone marrow stem cells (BMSCs) through Transwell^TM plates, and the results indicated that the relative cell viability, alkaline phosphatase (ALP) activity and mineralization of BMSCs were significantly higher with Zn–PAA as compared to PAA. Moreover, the Zn–PAA was cultured with RAW264.7 cells, and the results suggested an inhibiting effect of Zn–PAA on the cell differentiation into osteoclasts. In addition, Zn–PAA exhibited an antibacterial activity against both S. aureus and E. coli. These findings suggest that simonkolleite coating with certain contents could promote osteogenesis, suppress osteoclast formation and inhibit bacteria, indicating a novel way of enhancing the functionality of synthetic bone graft material and identifying the underline principles for designing zinc-containing bone grafts.

Liquid Exfoliation of Atomically Thin Antimony Selenide as an Efficient Two-Dimensional Antibacterial Nanoagent

The ever-growing global crisis of multidrug-resistant bacteria has triggered a tumult of activity in the design and development of antibacterial formulations. Here, atomically thin antimony selenide nanosheets (Sb₂Se₃ NSs), a minimal-toxic and low-cost semiconductor material, were explored as a high-performance two-dimensional (2D) antibacterial nanoagent via a liquid exfoliation strategy integrating cryo-pretreatment and polyvinyl pyrrolidone (PVP)-assisted exfoliation. When cultured with bacteria, the obtained PVP-capped Sb₂Se₃ NSs exhibited intrinsic long-term antibacterial capability, probably due to the reactive oxygen species generation and sharp edge-induced membrane cutting during physical contact between bacteria and nanosheets. Upon near-infrared laser irradiation, Sb₂Se₃ NSs achieved short-time hyperthermia sterilization because of strong optical absorption and high photothermal conversion efficiency. By virtue of the synergistic effects of these two broad-spectrum antibacterial mechanisms, Sb₂Se₃ NSs exhibited high-efficiency inhibition of conventional Gram-negative Escherichia coli, Gram-positive methicillin-resistant Staphylococcus aureus, and wild bacteria from a natural water pool. Particularly, these three categories of bacteria were completely eradicated after being treated with Sb₂Se₃ NSs (300 μM) plus laser irradiation for only 5 min. In vivo wound healing experiment further demonstrated the high-performance antibacterial effect. In addition, Sb₂Se₃ NSs depicted excellent biocompatibility due to the biocompatible element constitute and bioinert PVP modification. This work enlightened that atomically thin Sb₂Se₃ NSs hold great promise as a broad-spectrum 2D antibacterial nanoagent for various pathogenic bacterial infections.

Study of potential biomedical application of sol-gel derived Zn-doped SiO2-hydroxypropyl cellulose nanohybrids

A series of Zn-doped hybrid materials based on silica from tetraethoxysilane (TEOS) and hydroxypropyl cellulose (HPC) were prepared by a sol-gel route. The structure, morphology and thermal behavior of synthesized hybrids were characterized by infrared (IR) spectroscopy, ultraviolet-visible spectroscopy (UV-Vis), transmission electron microscopy (TEM) and differential thermal analysis with thermogravimetric analysis (DTA/TG). The obtained materials were investigated for a potential biomedical application. The antibacterial properties of hybrids were investigated by measuring the inhibition zones formed around the materials containing different zinc content in presence of reference strains of Gram-positive and Gram-negative bacteria. The biocompatibility tests showed no cytotoxicity and genotoxicity, as well as no changes in actin cytoskeleton organization for hybrids with Zn content below 5 wt%.

Additively manufactured porous metallic biomaterials

Additively manufactured (AM, =3D printed) porous metallic biomaterials with topologically ordered unit cells have created a lot of excitement and are currently receiving a lot of attention given their great potential for improving bone tissue regeneration and preventing implant-associated infections.