Synthesis, characterization of ZnO-chitosan nanocomposites and evaluation of its antifungal activity against pathogenic Candida albicans

Advancements in nanoparticle-based therapies for multidrug-resistant candidiasis infections: a comprehensive review

Candida auris, a rapidly emerging multidrug-resistant fungal pathogen, poses a global health threat, with cases reported in over 47 countries. Conventional detection methods struggle, and the increasing resistance ofC. auristo antifungal agents has limited treatment options. Nanoparticle-based therapies, utilizing materials like silver, carbon, zinc oxide, titanium dioxide, polymer, and gold, show promise in effectively treating cutaneous candidiasis. This review explores recent advancements in nanoparticle-based therapies, emphasizing their potential to revolutionize antifungal therapy, particularly in combatingC. aurisinfections. The discussion delves into mechanisms of action, combinations of nanomaterials, and their application against multidrug-resistant fungal pathogens, offering exciting prospects for improved clinical outcomes and reduced mortality rates. The aim is to inspire further research, ushering in a new era in the fight against multidrug-resistant fungal infections, paving the way for more effective and targeted therapeutic interventions.

Mesoporous zinc oxide-based drug delivery system offers an antifungal and immunoregulatory strategy for treating keratitis

Fungal keratitis is a refractory eye disease that is prone to causing blindness. Fungal virulence and inflammatory responses are two major factors that accelerate the course of fungal keratitis. However, the current antifungal drugs used for treatment usually possess transient residence time on the ocular surface and low bioavailability deficiencies, which limit their therapeutic efficacy. In this work, natamycin (NATA)-loaded mesoporous zinc oxide (Meso-ZnO) was synthesized for treating Aspergillus fumigatus keratitis with excellent drug-loading and sustained drug release capacities. In addition to being a carrier for drug delivery, Meso-ZnO could restrict fungal growth in a concentration-dependent manner, and the transcriptome analysis of fungal hyphae indicated that it inhibited the mycotoxin biosynthesis, oxidoreductase activity and fungal cell wall formation. Meso-ZnO also promoted cell migration and exhibited anti-inflammatory role during fungal infection by promoting the activation of autophagy. In mouse models of fungal keratitis, Meso-ZnO/NATA greatly reduced corneal fungal survival, alleviated tissue inflammatory damage, and reduced neutrophils accumulation and cytokines expression. This study suggests that Meso-ZnO/NATA can be a novel and effective treatment strategy for fungal keratitis.

Evaluation of Cytotoxicity and Antimicrobial Activity of Experimental Composites Containing Chitosan-Silver Oxide Particles Against Two Main Pathogenic Bacteria in Periodontal Disease

INTRODUCTION

Bacterial biofilm is known as the main cause of periodontal disease. Generally, the anaerobic Gram-negative, such as Porphyromonas gingivalis and Fusobacterium nucleatum, are considered the most identified bacteria.

OBJECTIVE

This study aimed to investigate the antimicrobial effect and cytotoxicity of two experimental composites containing chitosan-silver oxide (CH-Ag2O) particles.

MATERIALS AND METHODS

Four experimental groups, including Ag2O and CH, along with two composites of CH-Ag2O 20 and CH-Ag2O 60 mg, were prepared. Antimicrobial activity was performed against Porphyromonas gingivalis (ATCC#33277) and Fusobacterium nucleatum (ATCC#25586) using the agar dilution method. Moreover, the cytotoxicity assay was performed on human gingival fibroblasts (HGF) by the use of the MTT method. The obtained data were analyzed with descriptive methods, one-way ANOVA, and Tukey's LSD tests.

RESULTS

The antibacterial activity of both composites was higher than both CH and Ag2O, and the greatest antibacterial properties were presented in CH-Ag2O 60. In all three measurements (24, 48, and 72 h), the greatest cytotoxicity was seen in Ag2O, followed by CH, CH-Ag2O 20, and CHAg2O 60 in descending order, respectively. The cytotoxicity of these components was related to the concentration and not to the time of exposure. The results showed that Ag2O in 3.7 and 7.5 μg/ml concentrations and CH-containing groups in 250 and 500 μg/ml were toxic to the cultured HGF.

CONCLUSION

The experimental composite containing CH-Ag2O 60 showed the greatest antibacterial properties against two periodontal pathogens evaluated. In order to clarify the clinical significance of composite cytotoxicity, further clinical studies are necessary.

Formulation and antibacterial properties of lollipops containing of chitosan- zinc oxide nano particles on planktonic and biofilm forms of Streptococcus mutans and Lactobacillus acidophilus

This study aimed to formulate and characterize the experimental lollipops containing chitosan- zinc oxide nanoparticles (CH-ZnO NPs) and investigate their antimicrobial effects against some cariogenic bacteria. The CH-ZnO NPs were synthesized and characterized by X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR) analysis, and Transmission electron microscope (TEM). Then, four groups were made, including lollipops coated with 2 and 4 ml of CH-ZnO NPs, 0.7 ml CH-ZnO NPs incorporated lollipops, and those with no CH-ZnO NPs. Their antibacterial effectiveness against Streptococcus mutans and Lactobacillus acidophilus was evaluated by direct contact test and tissue culture plate method in planktonic and biofilm phases, respectively. Chlorhexidine mouthrinse (CHX) was used as a positive control group. In the planktonic phase, the antibacterial properties of both groups coated with CH-ZnO NPs were comparable and significantly higher than incorporated ones. There was no significant difference between CHX and the lollipops coated with 4 ml of NPs against S. mutans and CHX and two coated groups against L. acidophilus. None of the experimental lollipops in the biofilm phase could reduce both bacteria counts. The experimental lollipops coated with 2 and 4 ml of CH-ZnO NPs could reveal favorable antimicrobial properties against two cariogenic bacteria in the planktonic phase.

Sustainable remediation of toxic congo red dye pollution using bio based carbon nanocomposite: Modelling and performance evaluation

Remediation of synthetic dyes found in aqueous environment poses a serious challenge for treatment due to their resistance to chemical and biological degradation. This research study investigated the application of Chitosan-ZnO-Seaweed bio nanocomposite in the remediation of congo red. The novel bionanocomposite was characterised by FTIR, SEM, TEM, EDS and XRD studies. The FTIR spectra and SEM images indicated the adsorption of congo red onto the synthesized bionanocomposite. The batch wise experimental studies were done to explore the influence of process variables on removal of congo red from synthetic wastewater and to determine optimized conditions. Under optimized conditions of pH 3, temperature 40 °C, initial congo red concentration 50 mg/L, bionanocomposite quantity 0.03 g/L and interaction period 30 min, the bionanocomposite removed 95.64% of congo red. Thermodynamic studies were carried out and the parameters, ΔH° and ΔS° were found to be 38.386 kJ/mol and 0.1451 kJ/mol. K, respectively. The isotherm and kinetic study showed that monolayer Langmuir model was obeyed (R2 = 0.968) and the experimental value of congo red adsorption correlated well with pseudo second order model (R2 = 0.9938) respectively. The maximum adsorption capacity was found to be 303.03 mg/g. Protonated amino group of chitosan, hydroxyl group of seaweed accounts for congo red adsorption along with zinc oxide.

Fabrication of Antibacterial and Antioxidant ZnO-Impregnated Amine-Functionalized Chitosan Bio-Nanocomposite Membrane for Advanced Biomedical Applications

Developing a variety of safe and effective functioning wound dressings is a never-ending objective. Due to their exceptional antibacterial activity, biocompatibility, biodegradability, and healing-promoting properties, functionalized chitosan nanocomposites have attracted considerable attention in wound dressing applications. Herein, a novel bio-nanocomposite membrane with a variety of bio-characteristics was created through the incorporation of zinc oxide nanoparticles (ZnONPs) into amine-functionalized chitosan membrane (Am-CS). The developed ZnO@Am-CS bio-nanocomposite membrane was characterized by various analysis tools. Compared to pristine Am-CS, the developed ZnO@Am-CS membrane revealed higher water uptake and adequate mechanical properties. Moreover, increasing the ZnONP content from 0.025 to 0.1% had a positive impact on antibacterial activity against Gram-positive and Gram-negative bacteria. A maximum inhibition of 89.4% was recorded against Escherichia coli, with a maximum inhibition zone of 38 ± 0.17 mm, and was achieved by the ZnO (0.1%)@Am-CS membrane compared to 72.5% and 28 ± 0.23 mm achieved by the native Am-CS membrane. Furthermore, the bio-nanocomposite membrane demonstrated acceptable antioxidant activity, with a maximum radical scavenging value of 46%. In addition, the bio-nanocomposite membrane showed better biocompatibility and reliable biodegradability, while the cytotoxicity assessment emphasized its safety towards normal cells, with the cell viability reaching 95.7%, suggesting its potential use for advanced wound dressing applications.

Green nanocoating-based polysaccharides decorated with ZnONPs doped Egyptian kaolinite for antimicrobial coating paper

Paper coating plays an important role in the paper properties, printability and application. The nanocoating is a multifunction layer that provides the paper with unique features. In this work, nanocoating formulas were prepared using a green method and component. The nanocoating formulas were based on biopolymers nanostarch NSt and nanochitosan NCh (NCS) decorated with Egyptian kaolinite Ka doped with zinc nanoparticles NCS@xka/ZnONPs (x represents different ratios) support for multifunctional uses. The nanocoating formulas were characterized using a physiochemical analysis as well as a topographical study. FTIR, XRD, SEM and TEM techniques were used. Additionally, the antimicrobial activity of the tested samples was assessed against six microorganisms including Gram-negative and Gram-positive bacteria. The prepared nanocoating formulas affirmed excellent antimicrobial activity as a broad-spectrum antimicrobial active agent with excellent activity against all representative microbial communities. The nanocoating with the highest ratio of Ka/ZnONPs (NCS@40 ka/ZnONPs) showed excellent antimicrobial activity with an inhibition percentage of more than 70% versus all microorganisms presented. The paper was coated with the prepared suspensions and characterized concerning optical, mechanical and physical properties. When Ka/ZnONPs were loaded into NCS in a variety of ratios, the characteristics of coated paper were enhanced compared to blank paper. The sample NCS@40 ka/ZnONPs increased tensile strength by 11%, reduced light scattering by 12%, and improved brightness and whiteness by 1%. Paper coated with NCh suspension had 35.32% less roughness and 188.6% less porosity. When coated with the sample NCS@10 ka/ZnONPs, the coated paper's porosity was reduced by 94% and its roughness was reduced by 10.85%. The greatest reduction in water absorptivity was attained by coating with the same sample, with a reduction percentage of 132%.

Hybrid nanomaterial composed of chitosan, curcumin, ZnO and TiO2 for antibacterial therapies

Metal nanoparticles have been tremendously utilised, such as; antibacterial and anticancer agents. Although metal nanoparticles exhibits antibacterial and anticancer activity, but the drawback of toxicity on normal cells limits their clinical applications. Therefore, improving the bioactivity of hybrid nanomaterials (HNMs) and minimizing toxicity is of paramount importance for biomedical applications. Herein, a facile and simple double precipitation method was used to develop biocompatible and multifunctional HNM from antimicrobial chitosan, curcumin, ZnO and TiO₂. In HNM, biomolecules chitosan and curcumin were used to control the toxicity of ZnO and TiO₂ and improve their biocidal properties. The cytotxicological properties of the HNM was studied against human breast cancer (MDA-MB-231) and fibroblast (L929) cell lines. The antimicrobial activity of the HNM was examined against Escherichia coli and Staphylococcus aureus bacteria, via the well-diffusion method. In addition, the antioxidant property was evaluated by the radical scavenging method. These findings actively, support the ZTCC HNMs potential, as an innovative biocidal agent for applications in the clinical and healthcare sectors.

Antimicrobial Nano-Zinc Oxide Biocomposites for Wound Healing Applications: A Review

Chronic wounds are a major concern for global health, affecting millions of individuals worldwide. As their occurrence is correlated with age and age-related comorbidities, their incidence in the population is set to increase in the forthcoming years. This burden is further worsened by the rise of antimicrobial resistance (AMR), which causes wound infections that are increasingly hard to treat with current antibiotics. Antimicrobial bionanocomposites are an emerging class of materials that combine the biocompatibility and tissue-mimicking properties of biomacromolecules with the antimicrobial activity of metal or metal oxide nanoparticles. Among these nanostructured agents, zinc oxide (ZnO) is one of the most promising for its microbicidal effects and its anti-inflammatory properties, and as a source of essential zinc ions. This review analyses the most recent developments in the field of nano-ZnO–bionanocomposite (nZnO-BNC) materials—mainly in the form of films, but also hydrogel or electrospun bandages—from the different preparation techniques to their properties and antibacterial and wound-healing performances. The effect of nanostructured ZnO on the mechanical, water and gas barrier, swelling, optical, thermal, water affinity, and drug-release properties are examined and linked to the preparation methods. Antimicrobial assays over a wide range of bacterial strains are extensively surveyed, and wound-healing studies are finally considered to provide a comprehensive assessment framework. While early results are promising, a systematic and standardised testing procedure for the comparison of antibacterial properties is still lacking, partly because of a not-yet fully understood antimicrobial mechanism. This work, therefore, allowed, on one hand, the determination of the best strategies for the design, engineering, and application of n-ZnO-BNC, and, on the other hand, the identification of the current challenges and opportunities for future research.

Design, Synthesis, and Characterization of Novel Bis-Uracil Chitosan Hydrogels Modified with Zinc Oxide Nanoparticles for Boosting Their Antimicrobial Activity

A new series of hydrogels was successfully prepared by incorporating various substituted bisuracil (R-BU) linkages between chitosan Schiff's base chains (R-BU-CsSB) and between chitosan chains (R-BU-Cs). After protection of the amino groups of chitosan by benzaldehyde, yielding chitosan Schiff's base (CsSB), the reaction with epichlorohydrin was confined on the -OH on C6 to produce epoxy chitosan Schiff's base (ECsSB), which was reacted with R-BU to form R-BU-CsSB hydrogels, and finally, the bioactive amino groups of chitosan were restored to obtain R-BU-Cs hydrogels. Further, some R-BU-Cs-based ZnO nanoparticle (R-BU-Cs/ZnONPs) composites were also prepared. Appropriate techniques such as elemental analysis, FTIR, XRD, SEM, and EDX were used to verify their structures. Their inhibition potency against all the tested microbes were arranged as: ZnONPs bio-composites > R-BU-Cs hydrogels > R-BU-CsSB hydrogels > Cs. Their inhibition performance against Gram-positive bacteria was better than Gram-negative ones. Their minimum inhibitory concentration (MIC) values decreased as a function of the negative resonance effect of the substituents in the aryl ring of R-BU linkages in the hydrogels. Compared with Vancomycin, the ZnONPs bio-composites showed superior inhibitory effects against most of the tested Gram-negative bacteria, all inspected Gram-positive ones, and all investigated fungi.

HSBM-Produced Zinc Oxide Nanoparticles: Physical Properties and Evaluation of Their Antimicrobial Activity against Human Pathogens

This work examines the antibacterial and anticandidal activities of zinc oxide nanoparticles (ZNPs) synthesized by high-speed ball milling (HSBM), for short milling times: 0.5, 1, 1.5, and 2 h. First, ZNPs have been characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, and the Zetasizer analyzer. The HSBM results in semispherical ZNPs with some local agglomeration. We found that nanoparticles decrease in size continuously with milling time until they reach about 84% of their original size after only two hours; at 1000 rpm, HSBM reduces ZNP's average size by 6 nm/min. As particle size decreases, the X-ray diffracted patterns become broader and less intense while confirming that no phase transformation has occurred, proving HSBM's effectiveness in synthesizing nanoparticles on a large scale within a short period of time. According to FT-IR analysis, as material sizes change, the polarization charge of the ZNP surface changes as well, creating discrepancies in vibrational frequency, as demonstrated by the shifting of the IR spectra in the 300-600 cm^-1 frequency band. Raman responses have also been proven to depend on the particle size. Using the Agar well diffusion method, eleven microorganisms have been tested for the antimicrobial activity of ZNPs. Among the six Gram-negative tested bacteria, S. sonnei showed the largest inhibition zone of about 11.3 ± 0.6 mm with ZNPs measuring 148 nm in size (milled for 2 h), followed by E. coli ATCC 25922. Accordingly, S. aureus was the most susceptible Gram-positive bacteria, with inhibition zone size gradually increasing from 11.8 ± 0.3 mm to 13.5 ± 0.5 mm with decreasing nanoparticle size from 767 to 148 nm, while S. aureus ATCC 25923 was resistant to both milled and unmilled samples. Similar results were seen with candida, all milled ZNPs inhibited C. albicans, followed by C. tropicalis, whereas C. knisei was resistant to all ZNP sizes. In light of microorganism-ZNP interaction mechanisms, the obtained results have been discussed in depth.

Catalytic Reduction of Dyes and Antibacterial Activity of AgNPs@Zn@Alginate Composite Aerogel Beads

This work focuses on the preparation of aerogel composite beads based on Zn(II)-crosslinked alginate and loaded with different percentages of AgNPs using a simple approach. The obtained samples were evaluated in two different applications: the first application consists in their use as catalysts for the reduction of MB, MO, OG and CR dyes in a simple and binary system under the presence of NaBH₄. For this, several parameters affecting the catalytic behavior of these catalysts have been investigated and discussed such as the catalyst mass, AgNPs content, dye nature, and the selectivity of the catalyst in a binary system. The second application concerns their antibacterial activities towards two Gram-negative bacteria Escherichia coli (ATCC 25922), and Pseudomonas aeruginosa (ATCC 27853), and a Gram-positive bacteria Staphylococcus aureus (ATCC 25923). The physico-chemical properties of different samples were characterized by XRD, FTIR, SEM/EDS, and TGA analysis. The obtained results confirmed the presence of AgNPs on a highly porous alginate structure. The dispersion of a high percentage of AgNPs leads to the formation of nanoparticles on the outer surface of the alginate which led to their leaching after the catalytic test, while the composite having a low percentage of AgNPs showed good results through all dyes without leaching of AgNPs. For the antibacterial application of the different samples, it was shown that a composite with a higher percentage of AgNPs was the most effective against all bacteria.

Antimicrobial activity of the biologically synthesized zinc oxide nanoparticles against important rice pathogens

Global rice production is seriously affected by many abiotic and biotic factors. Among the aggressive rice pathogens, Xanthomonas oryzae pv. oryzae (X. o. pv. oryzae), Bipolaris oryzae (B. oryzae) and Sphaerulina oryzina (S. oryzina) cause bacterial leaf blight, brown leaf spot and narrow brown leaf spot diseases, respectively. The objective of this study was to evaluate the efficacy of biogenic zinc oxide nanoparticles (ZnO NPs) as antimicrobial agent to control rice pathogens. This is the first report of antifungal activity evaluation of ZnO NPs against B. oryzae and S. oryzina. A pre-characterized bacterial strain Escherichia sp. SINT7 was bio-prospected for synthesis of green ZnO NPs. The NPs were confirmed by a characteristic peak measured at 360.96 nm through UV-Vis spectroscopy. Further, the NPs were characterized to elucidate the surface capping molecules, crystallite structure and morphology by various spectroscopic and imaging techniques, which confirmed the spherical shape of NPs with size ranging from 13.07 to 22.25 nm. In vitro studies against X. o. pv. oryzae pathogen depicted the substantial antibacterial activity (up to 25.7 mm inhibition zone at 20 μg/ml NPs concentration). Similarly, ZnO NPs reduced the mycelial growth of B. oryzae and S. oryzina up to 72.68 and 95.78%, respectively at 50 μg/ml concentration on potato dextrose agar plates, while the mycelial biomass reduction was found to be 64.66 and 68. 49% for B. oryzae and S. oryzina, respectively on potato dextrose broth media as compared to control without the addition of NPs. The green ZnO NPs also significantly reduced the fungal spore germination and a disintegration of fungal hyphae for both fungal strains was observed under the microscope as a result of NPs treatment. Hence, it was concluded that biologically synthesized ZnO NPs are potential antimicrobials and could be compared in greenhouse pathogenicity assays with commercial pesticides to control rice pathogens.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-022-01251-y.

Synergistic effect of ZnO nanoparticles and hesperidin on the antibacterial properties of chitosan

In this study, hesperidin (HSP) biological agent, which has strong antioxidant properties, was successfully transferred to ZnO nanoparticles, which were first synthesized by the hydrothermal method. Then, chitosan (CS)/ZnO-HSP nanocomposites were produced by adding different ratios of the ZnO-HSPs to the biodegradable CS biopolymer by hydrothermal method. The resulting materials were characterized using various biophysical strategies, including X-ray diffraction (XRD), Fourier transform infrared spectrometry, scanning electron microscopy (SEM), and energy dispersive X-ray spectroscopy. The mean particle size of ZnO was estimated to be 29 nm from the XRD calculations and SEM measurements. The effect of the ZnO-HSPs on the thermal properties of pure CS was investigated by thermogravimetric analysis and differential scanning calorimetry techniques, and improvements were noted in the thermal properties of CS. While the T_g value of CS was 81 °C, this value increased by 13-94 °C with the addition of 6 wt% by weight of the ZnO-HSP. The antibacterial effect of materials was determined by the disc diffusion method. The ZnO-HSPs added to the CS caused the nanocomposites to have a remarkable effect against Escherichia coli and Staphylococcus aureus microorganisms. While the inhibition diameter of the CS against E. coli was 18.3, the same value increased to 22.3 for the composite containing 6 wt% the ZnO-HSP. The HSP increased the antioxidant capacity of both the ZnO-HSP particles and the CS/ZnO-HSP nanocomposites, reducing the toxic effects of ZnO nanoparticles. Thus, it was determined that the CS/ZnO-HSP nanocomposites did not have any cytotoxicity in healthy human cells. The fact that the produced nanocomposites exhibit antibacterial activity and do not harm human cells shows that they can be a safe product for health. From all these results, this triple hybrid system is hoped that it will be used in biomedical applications as a naturally-sourced, environmentally friendly, and cost-effective composite biomaterial by combining its antimicrobial and strong antioxidant properties.

Marine polysaccharide laminarin embedded ZnO nanoparticles and their based chitosan capped ZnO nanocomposites: Synthesis, characterization and in vitro and in vivo toxicity assessment

In the current scenario where more and more products containing nanomaterials are on the technological or pharmaceutical market, it is crucial to have a thorough knowledge of their toxicity before proposing possible applications. A proper analysis of the toxicity of the nanoproducts should include both in vitro and in vivo biological approaches and should consider that the synthesis and purification methods of nanomaterials may affect such toxicity. In the current work, the green synthesis of laminarin embedded ZnO nanoparticles (Lm-ZnO NPs) and their based chitosan capped ZnO nanocomposites (Ch-Lm-ZnO NCmps) is described for the first time. Furthermore, the evaluation of their in vitro cytotoxicity, phytotoxicity, and in vivo (Zebrafish embryo) toxicity was described. First, the green synthesized Lm-ZnO NPs and Ch-Lm-ZnO NCmps were fully physicochemically characterized. Lm-ZnO NPs were greatly agglomerated and had a spindle morphology ranging from 100 to 350 nm, while Ch-Lm-ZnO NCmps had irregular rod shape with flake-like structure clusters randomly aggregated with diverse sizes ranging from 20 to 250 nm. The in vitro cytotoxicity assessment of the green synthesized Lm-ZnO NPs and Ch-Lm-ZnO NCmps was carried out in normal human dermal fibroblasts (HDF) cells and human colon cancer (HT-29) cells by MTT assay. Lm-ZnO NPs and Ch-Lm-ZnO NCmps (0.1-500 μg/mL), significantly inhibited the viability of both cell lines, revealing dose-dependent cytotoxicity. Besides, the Lm-ZnO NPs and Ch-Lm-ZnO NCmps significantly affected seed germination and roots and shoots length of mung (Vigna radiata). Moreover, the zebrafish embryo toxicity of Lm-ZnO NPs and Ch-Lm-ZnO NCmps among the various concentrations used (0.1-500 μg/mL) caused deformities, increased mortality and decreased the survival rate of zebrafish embryo dose-dependently.

Ca2Fe2O5 powder antifungal activity to the Candida utilis culture upon its growth

This study reports the impact of Ca₂Fe₂O₅ porous powder on the yeast Candida utilis-as a fungal model-at different phases of growth, i.e., early exponential (6 h), mid-log (11 h), and stationary (17 h) phases. Ca₂Fe₂O₅ inhibited the cell growth in a time-dependent manner. After 120 min incubation, the fungicidal activity of porous powder was observed, i.e., log reduction of 2.81 and 2.58 for 11 and 17 h cultures, respectively, reaching the maximum of 4 log reduction after 7 days. Nevertheless, the 6 h culture of C. utilis showed enhanced resistance to Ca₂Fe₂O₅ with a ≤ 0.4 log reduction during the 7 days exposure. Our results not only showed that Ca₂Fe₂O₅ has the potential to effectively eliminate the C. utilis cell growth but also indicated the importance of the yeast culture physiological state for resistance to Ca₂Fe₂O₅. To the best of our knowledge, this is the first study that evaluated the fungicidal activity of Ca₂Fe₂O₅ porous powder on C. utilis and the impact of the C. utilis phase of growth on the cell susceptibility.

Accelerative effect of nanohydrogels based on chitosan/ZnO incorporated with citral to heal the infected full-thickness wounds; an experimental study

Antimicrobial-resistant is a major challenge in to treat infected wounds, and new formulations should be produced. Citral (Citl), chitosan (Chsn), and zinc oxide (ZnO) nanoparticles may accelerate the wound healing process in terms of their antibacterial properties. This new study aimed to investigate the effects of ointments produced from ZnO/Chsn/Citl nanoparticles (NPs) to treat the infected wounds. Following the preparation of ZnO/Chsn/Citl-NPs, swelling behavior, the release of citral, toxicity, and antibacterial properties were evaluated. Base ointment, mupirocin, and ointments made from Chsn-NPs, Chsn/Citl-NPs, and ZnO/Chsn/Citl-NPs were used to treat the mice. The ointments' effects on wound contraction, total bacterial count, and immunofluorescence staining for TNF-α, TGF-β, and bFGF were tested. The synthesis of ZnO/Chsn/Citl-NPs was validated by XRD, FT-IR, DLS, and TEM findings. In higher dilutions, chitosan/citral and ZnO/Chsn/Citl-NPs indicated better antibacterial activity. Nanoparticles were safe up to concentration of the 0.5 mg/mL. The mice in Chsn/Citl and ZnO/Chsn/Citl-NPs treated groups showed higher (P < 0.05) wound contraction ratio and expressions for bFGF, and lower total bacterial count and expressions for TGF-β and TNF-α compared to control mice. Ointments prepared from ZnO/Chsn/Citl-NPs could compete with the commercial ointment of mupirocin and can be used to treat infected wounds after clinical studies.

Zinc oxide nanoparticles-impregnated chitosan surfaces for covalent immobilization of trypsin: Stability & kinetic studies

Trypsin (Try, EC. 3.4.21.4) was effectively immobilized on the surface of glutaraldehyde(GA)-activated ZnO/Chitosan nanocomposite through covalent attachment via Schiff-base linkages. Size, structure, surface morphology, & percentage elemental composition of the prepared ZnO nanoparticles and chitosan-coated ZnO nanocomposite were studied by UV-Visible spectroscopy, Fourier-transform infrared spectroscopy (FTIR), X-Ray diffraction analysis (XRD), transmission electron microscopy (TEM), Scanning electron microscopy (SEM), and Energy-Dispersive X-Ray Microanalysis (EDAX) techniques. Optimal immobilization conditions (incubation time (16 h), enzyme concentration (1.8 mg/ml), and pH (7.8)) were investigated to obtain the maximum expressed activity of the immobilized trypsin. Immobilized & solubilized trypsin exhibited the optimum catalytic activity at pH 8.5, 60 °C, and pH 7.8, 45 °C respectively. Kinetic parameters (K_m, V_max) of immobilized (27.12 μM, 8.82 μM/min) & free trypsin (25.76 μM, 4.16 μM/min) were determined, indicating that efficiency of trypsin improves after immobilization. Immobilized trypsin preserved 67% of initial activity at 50 °C during 2 h of incubation & sustained nearly 50% of catalytic activity until the 9th repeated cycle of utilization. Moreover, immobilized trypsin retained 50% of enzymatic activity after 90 days of storage at 4 °C. Hence, the current findings suggest that ZnO/Chitosan-GA-Trypsin would be a promising biocatalyst for large-scale biotechnological applications.

Facile fabrication of ternary MWCNTs/ZnO/Chitosan nanocomposite for enhanced photocatalytic degradation of methylene blue and antibacterial activity

Developing a cheap, stable and effective photocatalyst is necessary for remediation of persistent organic pollutants. To address this challenge, we proposed a unique interfacial engineering technique and proper bandgap matching strategy to synthesize MWCNTs/ZnO/Chitosan ternary nanocomposite for effective photocatalytic application. The features of the prepared samples were determined by FESEM, TEM, EDX, elemental mapping, AFM, FT-IR, XRD, UV–Vis spectroscopy and BET surface analysis. The obtained results showed successful fabrication of synthesized nanocomposites with enhanced surface area. Degradation effect of nanostructures on methylene blue (MB) and antibacterial activity against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Bacillus subtilis (B. subtilis) pathogenic strains were investigated. The proposed photocatalytic mechanism illustrated the electron transfer facilitated by MWCNTs/ZnO/Chitosan structure which results in spatial separation of electron–hole pairs. Compared with ZnO and ZnO/Chitosan, the prepared MWCNTs/ZnO/Chitosan ternary nanocomposite showed high usage of UV illumination and superior separation of photogenerated electron–hole pairs. MWCNTs/ZnO/Chitosan illustrated 86.26% adsorption rate and outstanding increased photocatalytic activity on MB degradation efficiency of 98.76% after 20 min. Stability of photocatalyst reached from 98.76% initial decolorization to 85% at the fourth cycle. In addition, the ternary nanocomposite also exhibited remarkable bactericidal activity against gram-positive (S. aureus) and (B. subtilis) and gram-negative (E. coli) bacteria strains. Due to the obtained results, the prepared nanocomposite would be an efficient candidate photocatalyst with antibacterial properties.

Synthesis and characterization of PCU@C-Ag/AgCl nanoparticles as an antimicrobial material for respiratory tract infection

The pregnant cow urine (PCU) is an active source of antimicrobial agents that is used for fabricating chitosan coated Ag/AgCl nanoparticles (NPs) in the present study. These PCU@C-Ag/AgCl NPs were physicochemically characterized and evaluated for antimicrobial activity against selected respiratory tract infection (RTI) pathogens. The absorption band around 420 nm in UV-Visible spectrum indicated the presence of Ag NPs. The spherical shape of NPs was observed using TEM. Also, the crystalline structure was confirmed using the XRD pattern. The PCU@C-Ag/AgCl NPs showed strong antimicrobial activity against all tested RTI pathogens. In addition, FESEM analysis showed morphological changes in RTI bacterial pathogens. Thereby, PCU@C-Ag/AgCl NPs may be used as an antimicrobial material to treat RTIs in near future at clinical level.

Fabrication of nano-decorated ZnO-fibrillar chitosan exhibiting a superior performance as a promising replacement for conventional ZnO

In this research, bioactive nano-hybrids based on the nano-fibrillar chitosan-ZnO (NF-CS-ZnO) were synthesized to diminish the toxicity of ZnO-NPs. The successful formation of nano-hybrids was confirmed by FT-IR, UV-Vis, and FE-SEM analyses, showing a uniform spherical ZnO-NPs with an average diameter of 20-30 nm, homogeneously dispersed on NF-CS. The obtained results demonstrated a remarkable antibacterial activity of NF-CS-ZnO-0.6 nano-hybrid against E. coli and S. aureus and, interestingly, no cytotoxic on normal cells (even at a high concentration of 100 μg/mL). Furthermore, NF-CS hybridization efficiently decreased the up-regulation in Cas3, Cas9, and Il6 of inspected fishes compared to the ZnO-NPs. Histopathological examination revealed hepatocyte necrosis in the fish exposed to ZnO-NPs and hyperemia exposed to NF-CS-ZnO-0.6 nano-hybrid. Finally, NF-CS efficiently improved the bio-safety and bactericidal activity of ZnO-NPs; therefore, NF-CS-ZnO nano-hybrid is prominently recommended as a talented low-toxicity antibacterial agent replacement of conventional ZnO-NPs for use in different applications.

Diatomaceous earth/zinc oxide micro-composite assisted antibiotics in fungal therapy

As the second wave of COVID-19 hits South Asia, an increasing deadly complication 'fungal infections (such as Mycosis, Candida and Aspergillus) outbreak' has been raised concern about the insufficient technologies and medicals for its diagnosis and therapy. Biosilica based nano-therapy can be used for therapeutic efficacy, yet their direct role as antibiotic agent with biocompatibility and stability remains unclear. Here, we report that a diatomaceous earth (DE) framework semiconductor composite conjugated DE and in-house synthesized zinc oxide (DE-ZnO), as an antibiotic agent for the enhancement of antibiotic efficacy and persistence. We found that the DE-ZnO composite had enhanced antibiotic activity against fungi (A. fumigatus) and Gram-negative bacteria (E. coli, S. enterica). The DE-ZnO composite provides enhancing large surface areas for enhancement of target pathogen binding affinity, as well as produces active ions including reactive oxygen species and metal ion for breaking the cellular network of fungi and Gram-negative bacteria. Additionally, the toxicity of DE-ZnO with 3 time less amount of dosage is 6 times lower than the commercial SiO₂-ZnO. Finally, a synergistic effect of DE-ZnO and existing antifungal agents (Itraconazole and Amphotericin B) showed a better antifungal activity, which could be reduced the side effects due to the antifungal agents overdose, than a single antibiotic agent use. We envision that this DE-ZnO composite can be used to enhance antibiotic activity and its persistence, with less-toxicity, biocompatibility and high stability against fungi and Gram-negative bacteria which could be a valuable candidate in medical science and industrial engineering.

Caspofungin-resistance in Candida auris is cell wall-dependent phenotype and potential prevention by zinc oxide nanoparticles

Candida auris is an emergent nosocomial multi-drug-resistant yeast that represents a global health threat. Recently, C. auris clinical isolates with caspofungin resistance were identified. Mutation in FKS1 gene was determined as a mechanism of resistance. However, the ability of C. auris to develop acquired and cross-resistance has never been investigated. Herein, this resistance ability due to caspofungin and associate mechanisms were investigated. C. auris clinical isolate was successively cultured for 10 generations in the presence of caspofungin compared to fluconazole-treatment and untreated controls. This was followed by the analysis of target gene expression and phenotypic changes. The obtained results showed that caspofungin-treated C. auris exhibited elevated MIC50(caspofungin), slower growth, elevated chitin content, overexpression of caspofungin target genes, and cross-resistance to fluconazole. Interestingly, caspofungin exposure induced cell-cell adhesion and biofilm formation. C. auris gradually lost caspofungin resistance after removal of antifungal pressure, while keeping the overexpression of fungal cell wall-related genes including ALS5. We propose that C. auris ageing in the presence of caspofungin caused the development of persistent phenotypic changes in the fungal cell wall, leading to acquired and physical cross-resistance mechanisms. Surprisingly, formulation of caspofungin in zinc oxide nanoparticles prevented the aforementioned behavioral changes regardless of the pathogen generations.

LAY SUMMARY

Candida auris developed resistance against caspofungin. Our data indicated that this resistance mechanism is unique because of changes in the genes related to cell wall adhesions. Formulation of caspofungin in ZnO nanoparticles was able to overcome these phenotypic changes.

Biodegradable Chitosan Films with ZnO Nanoparticles Synthesized Using Food Industry By-Products—Production and Characterization

This work aimed to produce bionanocomposites of chitosan incorporated with zinc oxide nanoparticles (ZnO NPs) synthesized using food industry by-products and to characterize them. Such nanoparticles are highlighted due to their low cost, antimicrobial activity, accessibility, and sustainability synthesis. Four different levels of ZnO NPs (0, 0.5, 1.0, and 2.0% w/w of chitosan) were tested, and the bionanocomposites were characterized in terms of their hydrophobicity, mechanical, optical, and barrier properties. Overall, the incorporation of ZnO NPs changed the composites from brittle to ductile, with enhanced elongation at break and reduced Young Modulus and tensile strength. Thus, ZnO NPs acted as plasticizer, turning the films more flexible, due to the presence of organic compounds on the NPs. This also favored permeability of oxygen and of water vapor, but the good barrier properties were maintained. Optical properties did not change statistically with the ZnO NPs incorporation. Thus, the characterization presented in this paper may contribute to support a decision on the choice of the material’s final application.

Bioengineered chitosan-magnesium nanocomposite: A novel agricultural antimicrobial agent against Acidovorax oryzae and Rhizoctonia solani for sustainable rice production

Chitosan is a potent biopolymer having promising antimicrobial properties against phytopathogens. Recently, engineered nanomaterials (ENMs) have gained much attention due to their potential application in the plant disease management. In this study, we reported the green synthesis of chitosan-magnesium (CS-Mg) nanocomposite and its antimicrobial activity against two rice pathogens namely Acidovorax oryzae and Rhizoctonia solani for the first time. The green MgO nanoparticles synthesized by using a native Bacillus sp. strain RNT3, were used to fabricate CS-Mg nanocomposite utilizing one-pot synthesis method. The synthesis of CS-Mg nanocomposite was further confirmed by using UV-vis spectroscopy, whereas, FTIR and XRD analysis showed the capping of CS-Mg nanocomposites by different functional groups together with their crystalline structure, respectively. Besides, SEM and TEM images revealed the spherical shape along with the particles size ranging from 29 to 60 nm. Moreover, EDS analysis confirmed the elemental purity of nanocomposite. The CS-Mg nanocomposite showed remarkable antimicrobial activity against A. oryzae and R. solani and significantly inhibited the growth as compared to non-treated control. The ultrastructure studies showed damaged structure of cell wall and internal cellular organelles after treatment with 100 μg mL^-1 CS-Mg nanocomposite. The results of this study indicated that CS-Mg nanocomposite-based antimicrobial agents could be considered as promising nanopesticides against phytopathogens in plant disease management.

Comparison of antifungal and cytotoxicity activities of titanium dioxide and zinc oxide nanoparticles with amphotericin B against different Candida species: In vitro evaluation

BACKGROUND

Candida species are known to cause serious fungal infections that produce cutaneous, mucosal, and systemic infections. Nowadays, mortality and morbidity candidiasis in immunocompromised patients have increased. Nanotechnology is a new world-known technology and includes particles ranging from about 1 to 100 nanometers. The purpose of this study was to evaluate the antifungal and cytotoxicity activities of titanium dioxide nanoparticles (TiO2-NPs) and zinc oxide nanoparticles (ZnO-NPs) compared to amphotericin B (AmB) on different Candida spp in in vitro conditions.

METHODS

In the present study, susceptibility of different Candida species to TiO2-NPs and ZnO-NPs compared to AmB was determined by broth microdilution (BMD) and agar well diffusion methods. Cytotoxicity of TiO2-NPs and ZnO-NPs and amphotericin B was measured by MTT (3-(4, 5-Dimethylthiazol-2-yl)-2, 5-Diphenyltetrazolium Bromide) assay.

RESULTS

The results indicated that the TiO2-NPs and ZnO-NPs showed antifungal activities against pathogenic Candida spp. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of TiO2-NP ranges against Candida spp. were 128-256 µg/mL and 256-512 µg/mL, respectively. The MIC and MFC values of ZnO-NPs were 64-128 µg/mL and 256-512 µg/mL, respectively. However, MICs and MFCs of AmB were 8-16 µg/mL and 16-32 µg/mL, respectively. The MTT assay results showed that the CC50% belonged to ZnO-NPs 706.2 μg/mL, for TiO2-NPs 862.1 μg/mL, and for AmB 70.19 μg/mL, respectively.

CONCLUSION

Our findings showed that TiO2-NPs and ZnO-NPs had antifungal effects against all Candida species, yet the antifungal properties of TiO2-NPs and ZnO-NPs were significantly less than those of AmB. The CC50% of AmB was significantly lower than ZnO-NPs and TiO2-NPs.

Synthesis of alternan-stabilized zinc nanoparticles: morphological, thermal, antioxidant and antimicrobial characterization

This study aimed to synthesize zinc nanoparticles with antimicrobial and antioxidant activities using alternan (ZnNPs-Alt) produced by Lactobacillus reuteri E81 as the stabilizing agent. For the characterization of the ZnNPs-Alt, UV-vis spectroscopy, SEM, TEM and EDX analysis, XRD, FTIR and DSC analysis were applied. The functional role of ZnNPs-Alt was tested by determination of their antioxidant activities by DPPH and CUPRAC methodologies and their antibacterial and antifungal activities. Results of this study demonstrated that alternan was utilized as a successful stabilizer to produce crystalline, thermally stabile ZnNPs-Alt with a particle size of ∼ 100 nm. Importantly, strong antioxidant and antimicrobial activities were observed for ZnNPs-Alt in a concentration dependent manner. These findings confirmed the role of alternan as a stabilizing agent for the production of ZnNPs-Alt with functional roles.

Incorporation of Nonyl 3,4-Dihydroxybenzoate Into Nanostructured Lipid Systems: Effective Alternative for Maintaining Anti-Dermatophytic and Antibiofilm Activities and Reducing Toxicity at High Concentrations

Dermatophytosis is the most common mycosis worldwide, affecting approximately 20 to 25% of the population, regardless of gender, race, color, and age. Most antifungal agents used for the treatment of dermatophytosis belong to the azole and allylamine classes. Dermatophytes are reported to be resistant to most commercial drugs, especially microbial biofilms, in addition to their considerable toxicity. It should be emphasized the importance of looking for new molecules with reduced toxicity, as well as new targets and mechanisms of action. This work aims to incorporate nonyl 3,4-dihydroxybenzoate, a potent fungicide compound against planktonic cells and dermatophyte biofilms in nanostructured lipid systems (NLS), in order to reduce toxicity in high concentrations, improve its solubility and maintain its effectiveness. The compound was incorporated into NLS constituted by cholesterol, mixture of polyoxyethylene (23) lauryl ether (Brij^®98) and soybean phosphatidylcholine (Epikuron^® 200)], 2: 1 ratio and PBS (phosphate-buffered saline). The characterization of the incorporation was performed. Susceptibility tests were conducted according to document M38-A2 by CLSI (2008). The toxicity of the NLS compound was evaluated in HaCaT cell lines by the sulforhodamine B method and in alternative models Caenorhabditis elegans and zebrafish. Finally, its efficacy was evaluated against the mature Trichophyton rubrum and Trichophyton mentagrophytes biofilms. NLS and nonyl 3,4-dihydroxybenzoate loaded into NLS displayed sizes ranging from 137.8 ± 1.815 to 167.9 ± 4.070 nm; the polydispersity index (PDI) varying from 0.331 ± 0.020 to 0.377 ± 0.004 and zeta potential ranging from −1.46 ± 0.157 to −4.63 ± 0.398 mV, respectively. Polarized light microscopy results confirmed the formation of NLS of the microemulsion type. Nonyl incorporated into NLS showed minimum inhibitory concentration (MIC) values, ranging from 2 to 15.6 mg/L. The toxicity tests presented cell viability higher than 80% in all tested concentrations, as well as, a significantly increased of the survival of Caenorhabditis elegans and zebrafish models. Anti-biofilm tests proved the efficacy of the incorporation. These findings contribute significantly to the search for new antifungals and allow the systemic administration of the compound, since the incorporation can increase the solubility of non-polar compounds, improve bioavailability, effectiveness and reduce toxicity.

Microwave-Assisted Green Synthesis and Antioxidant Activity of Selenium Nanoparticles Using Theobroma Cacao L. Bean Shell Extract

Selenium nanoparticles (SeNPs) are successfully synthesized through microwave heating by using Theobroma cacao L. bean shell extract as a stabilizing and capping agent. Response surface methodology is used to obtain optimal synthesis conditions. The effect of microwave power, irradiation time and amount of Na2SeO3 are evaluated on crystalline size by X-Ray Diffraction (XRD) and Z-potential by Dynamic Light Scattering (DLS) using a central composite design (CCD). Optimal synthesis conditions are determined as 15.6 min, 788.6 W and 0.14 g of sodium selenite using 50 mL of Theobroma cacao L. bean shell extract. The successful biosynthesis of SeNPs is confirmed by UV-visible and Fourier Transformed Infrared (FTIR) spectroscopic analyses. The XRD pattern and Raman spectra show the presence of trigonal and amorphous synthesized SeNPs. Spherical SeNPs are observed by Transmission Electron Microscopy (TEM) with a particle size of 1-3 nm in diameter, at least one order of magnitude lower than those previously reported. The obtained SeNPs can be stable up to 55 days at 4 °C. Additionally, the SeNPs show an excellent antioxidant performance by the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and ferric reducing antioxidant power (FRAP) methods, with potential application in different sectors, such as food, medical and pharmaceutical.

Antileishmanial activity and cytotoxicity of ZnO-based nano-formulations

INTRODUCTION

Nanoparticles (NPs) can be toxic due to their nano-range sizes. Zinc oxide (ZnO) has good biocompatibility and is commercially used in cosmetics. Moreover, ZnO NPs have potential biomedical uses, but their safety remains unclear.

METHODS

A range of doped ZnO NPs was evaluated for antileishmanial activity and in vitro toxicity in brine shrimp and human macrophages, and N-doped ZnO NPs were evaluated for in vivo toxicity in male BALB/C mice. N-doped ZnO NPs were administered via two routes: intra-peritoneal injection and topically as a paste. The dosages were 10, 50, and 100 mg/kg/day for 14 days.

RESULTS

Topical administration was safe at all dosages, but intra-peritoneal injection displayed toxicity at higher doses, namely, 50 and 100 mg/kg/day. The pathological results for the i.p. dose groups were mild to severe degenerative changes in parenchyma cells, increases in Kupffer cells, disappearance of hepatic plates, increases in cell size, ballooning, cytoplasmic changes, and nuclear pyknosis in the liver. Kidney histology was also altered in the i.p. administration group (dose 100 mg/kg/day), with inflammatory changes in the focal area. We associate pathological abnormalities with the presence of doped ZnO NPs at the diseased site, which was verified by PIXE analysis of the liver and kidney samples of the treated and untreated mice groups.

CONCLUSION

The toxicity of the doped ZnO NPs can serve as an essential determinant for the effects of ZnO NPs on environmental toxicity and can be used for guidelines for safer use of ZnO-based nanomaterials in topical treatment of leishmaniasis and other biomedical applications.

Preparation and characterization of hybrid chitosan-silver nanoparticles (Chi-Ag NPs); A potential antibacterial agent

In this study, a novel ecofriendly chitosan- silver nanoparticles hybrid was developed. Biological method using leaf extract of T. portulacifolium was used as reducing agent for its synthesis and the antibacterial efficiency of these hybrid nanoparticles were evaluated against the bacteria E. coli and S. marcescens organisms. The intense peak observed around 419 nm in the UV-Vis indicates the formation of silver nanoparticles. The XRD analysis showed that the hybrid chitosan-silver nanoparticles have a polycrystalline and face-centered cubic configuration. FTIR spectrum hybrid chitosan-silver nanoparticles indicated speaks vibration of NH and OH. The EDS analysis confirmed the presence of Ag, O, C and N elements in the prepared sample. The spherical shape was obtained from TEM analysis and it indicated that with average particles around 3.24 nm to 44.80 nm. The prepared hybrid chitosan-silver nanoparticles showed significant antibacterial activities against E. coli and S. marcescens. In addition, the surface membrane damages and surface morphology of test pathogens were visualized using FESEM analysis.

Zinc oxide nanoparticles: Biosynthesis, characterization, antifungal and cytotoxic activity

Zinc oxide nanoparticles (ZnO-NPs) are multifunctional oxide metal nanoparticles that have been considered by many due to their unique properties including UV filtration, semiconducting, antimicrobial, antifungal, and photocatalytic activity. In the present study, ZnO-NPs have been synthesized from Zn(SO₄)·7H₂O through the use of "green synthesis" method that utilizes Prosopis farcta aqueous extract. The characterization of synthesized ZnO-NPs have been performed by UV-Vis absorption, Fourier-Transform Infrared spectroscopy (FT-IR), Raman, Powder X-ray Diffraction (PXRD), Transmission Electron Microscopy (TEM), Field Emission Scanning Electron Microscopy (FESEM) and Energy Dispersive X-ray analysis (EDX). Results have illustrated that the synthesized nanoparticles contain a hexagonal shape and sheet form with sizes of 40-80 nm. The antifungal activity of ZnO-NPs against Candida albicans has shown that the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) were 128 and 256 μg/ml, respectively. The cytotoxicity activity of synthesized nanoparticles was tested on breast cancer cells (MCF7), while the IC₅₀ was calculated to be 90 μg/ml.