Anticandidal activity of biosynthesized silver nanoparticles: effect on growth, cell morphology, and key virulence attributes of Candida species

The antimicrobial effects of silver nanoparticles obtained through the royal jelly on the yeasts Candida guilliermondii NP-4

The effect of silver nanoparticles (Ag NPs) obtained in the presence of royal jelly (RJ) on the growth of yeast Candida guilliermondii NP-4, on the total and H+-ATPase activity, as well as lipid peroxidation process and antioxidant enzymes (superoxide dismutase (SOD), catalase) activity was studied. It has been shown that RJ-mediated Ag NPs have a fungicide and fungistatic effects at the concentrations of 5.4 µg mL-1 and 27 µg mL-1, respectively. Under the influence of RJ-mediated Ag NPs, a decrease in total and H+-ATPase activity in yeast homogenates by ~ 90% and ~ 80% was observed, respectively. In yeast mitochondria total and H+-ATPase activity depression was detected by ~ 80% and ~ 90%, respectively. The amount of malondialdehyde in the Ag NPs exposed yeast homogenate increased ~ 60%, the catalase activity increased ~ 70%, and the SOD activity-~ 30%. The obtained data indicate that the use of RJ-mediated Ag NPs have a diverse range of influence on yeast cells. This approach may be important in the field of biomedical research aimed at evaluating the development of oxidative stress in cells. It may also contribute to a more comprehensive understanding of antimicrobial properties of RJ-mediated Ag NPs and help control the proliferation of pathogenic fungi.

Reduction of biofilm and pathogenic microorganisms using curcumin-mediated photodynamic inactivation to prolong food shelf-life

Pathogenic microbial contamination (bacteria and fungi) in food products during production poses a significant global health risk, leading to food waste, greenhouse gas emissions, and aesthetic and financial losses. Bacteria and fungi, by forming solid biofilms, enhance their resistance to antimicrobial agents, thereby increasing the potential for cross-contamination of food products. Curcumin molecule-mediated photodynamic inactivation (Cur-m-PDI) technology has shown promising results in sterilizing microbial contaminants and their biofilms, significantly contributing to food preservation without compromising quality. Photosensitizers (curcumin) absorb light, leading to a chemical reaction with oxygen and producing reactive oxygen species (ROS) that effectively reduce bacteria, fungi, and biofilms. The mechanism of microorganism inhibition is caused by exposure to ROS generated via the type 1 pathway involving electron transfer (such as O2•-, H2O2, -OH•, and other radicals), the type 2 pathway involving energy transfer (such as 1O2), secondary ROS, and weakening of antioxidant enzymes. The effectiveness of the inactivation of microorganisms is influenced by the concentration of curcumin, light (source type and energy density), oxygen availability, and duration of exposure. This article reviews the mechanism of reducing microbial food contamination and inhibiting their biofilms through Cur-m-PDI. It also highlights future directions, challenges, and considerations related to the effects of ROS in oxidizing food, the toxicity of PDI to living cells and tissues, conditions/types of food products, and the stability and degradation of curcumin.

Phenotypic and Genotypic Characterization of Resistance and Virulence Markers in Candida spp. Isolated from Community-Acquired Infections in Bucharest, and the Impact of AgNPs on the Highly Resistant Isolates

BACKGROUND

This study aimed to determine, at the phenotypic and molecular levels, resistance and virulence markers in Candida spp. isolated from community-acquired infections in Bucharest outpatients during 2021, and to demonstrate the efficiency of alternative solutions against them based on silver nanoparticles (AgNPs).

METHODS

A total of 62 Candida spp. strains were isolated from dermatomycoses and identified using chromogenic culture media and MALDI-TOF MS, and then investigated for their antimicrobial resistance and virulence markers (VMs), as well as for metabolic enzymes using enzymatic tests for the expression of soluble virulence factors, their biofilm formation and adherence capacity on HeLa cells, and PCR assays for the detection of virulence markers and the antimicrobial activity of alternative solutions based on AgNPs.

RESULTS

Of the total of 62 strains, 45.16% were Candida parapsilosis; 29.03% Candida albicans; 9.67% Candida guilliermondii; 3.22% Candida lusitaniae, Candia pararugosa, and Candida tropicalis; and 1.66% Candida kefyr, Candida famata, Candida haemulonii, and Candida metapsilosis. Aesculin hydrolysis, caseinase, and amylase production were detected in the analyzed strains. The strains exhibited different indices of adherence to HeLa cells and were positive in decreasing frequency order for the LIP1, HWP1, and ALS1,3 genes (C. tropicalis/C. albicans). An inhibitory effect on microbial growth, adherence capacity, and on the production of virulence factors was obtained using AgNPs.

CONCLUSIONS

The obtained results in C. albicans and Candida non-albicans circulating in Bucharest outpatients were characterized by moderate-to-high potential to produce VMs, necessitating epidemiological surveillance measures to minimize the chances of severe invasive infections.

Nanoformulations for dismantling fungal biofilms: The latest arsenals of antifungal therapy

Globally, fungal infections have evolved as a strenuous challenge for clinicians, particularly in patients with compromised immunity in intensive care units. Fungal co-infection in Covid-19 patients has made the situation more formidable for healthcare practitioners. Surface adhered fungal population known as biofilm often develop at the diseased site to elicit antifungal tolerance and recalcitrant traits. Thus, an innovative strategy is required to impede/eradicate developed biofilm and avoid the formation of new colonies. The development of nanocomposite-based antibiofilm solutions is the most appropriate way to withstand and dismantle biofilm structures. Nanocomposites can be utilized as a drug delivery medium and for fabrication of anti-biofilm surfaces capable to resist fungal colonization. In this context, the present review comprehensively described different forms of nanocomposites and mode of their action against fungal biofilms. Amongst various nanocomposites, efficacy of metal/organic nanoparticles and nanofibers are particularly emphasized to highlight their role in the pursuit of antibiofilm strategies. Further, the inevitable concern of nanotoxicology has also been introduced and discussed with the exigent need of addressing it while developing nano-based therapies. Further, a list of FDA-approved nano-based antifungal formulations for therapeutic usage available to date has been described. Collectively, the review highlights the potential, scope, and future of nanocomposite-based antibiofilm therapeutics to address the fungal biofilm management issue.

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.

Silver Nanoparticle-Embedded Carbon Nitride: Antifungal Activity on Candida albicans and Toxicity toward Animal Cells

The development of engineered nanomaterials has been considered a promising strategy to control oral infections. In this study, silver-embedded carbon nitrides (Ag@g-CN) were synthesized and tested against Candida albicans, investigating their antifungal action and biocompatibility in animal cells. Ag@g-CN was synthesized by a simple one-pot thermal polymerization technique and characterized by various analytical techniques. X-ray diffraction (XRD) analysis revealed slight alterations in the crystal structure of g-CN upon the incorporation of Ag. Fourier transform infrared (FT-IR) spectroscopy confirmed the presence of Ag-N bonds, indicating successful silver incorporation and potential interactions with g-CN's amino groups. UV-vis spectroscopy demonstrated a red shift in the absorption edge of Ag@g-CN compared with g-CN, attributed to the surface plasmon resonance effect of silver nanoparticles. Field emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) confirmed the 2D layered sheet like morphology of both materials. The Ag 3d peaks found in X-ray photoelectron spectroscopy (XPS) confirmed the presence of metallic Ag0 nanoparticles in Ag@g-CN. The Ag@g-CN materials exhibited high antifungal activity against reference and oral clinical strains of C. albicans, with minimal inhibitory concentration (MIC) ranges between 16-256 μg/mL. The mechanism of Ag@g-CN on C. albicans was attributed to the disruption of the membrane integrity and disturbance of the biofilm. In addition, the Ag@g-CN material showed good biocompatibility in the fibroblastic cell line and in Galleria mellonella, with no apparent cytotoxicity observed at a concentration up to 1000 μg/mL. These findings demonstrate the potential of the Ag@g-CN material as an effective and safe antifungal agent for the treatment of oral fungal infections.

Insights into the anti-Candida albicans properties of natural phytochemicals: An in vitro and in vivo investigation

Invasive candidiasis, attributed to Candida albicans, has long been a formidable threat to human health. Despite the advent of effective therapeutics in recent decades, the mortality rate in affected patient populations remains discouraging. This is exacerbated by the emergence of multidrug resistance, significantly limiting the utility of conventional antifungals. Consequently, researchers are compelled to continuously explore novel solutions. Natural phytochemicals present a potential adjunct to the existing arsenal of agents. Previous studies have substantiated the efficacy of phytochemicals against C. albicans. Emerging evidence also underscores the promising application of phytochemicals in the realm of antifungal treatment. This review systematically delineates the inhibitory activity of phytochemicals, both in monotherapy and combination therapy, against C. albicans in both in vivo and in vitro settings. Moreover, it elucidates the mechanisms underpinning the antifungal properties, encompassing (i) cell wall and plasma membrane damage, (ii) inhibition of efflux pumps, (iii) induction of mitochondrial dysfunction, and (iv) inhibition of virulence factors. Subsequently, the review introduces the substantial potential of nanotechnology and photodynamic technology in enhancing the bioavailability of phytochemicals. Lastly, it discusses current limitations and outlines future research priorities, emphasizing the need for high-quality research to comprehensively establish the clinical efficacy and safety of phytochemicals in treating fungal infections. This review aims to inspire further contemplation and recommendations for the effective integration of natural phytochemicals in the development of new medicines for patients afflicted with C. albicans.

Secreted Aspartic Proteinases: Key Factors in Candida Infections and Host-Pathogen Interactions

Extracellular proteases are key factors contributing to the virulence of pathogenic fungi from the genus Candida. Their proteolytic activities are crucial for extracting nutrients from the external environment, degrading host defenses, and destabilizing the internal balance of the human organism. Currently, the enzymes most frequently described in this context are secreted aspartic proteases (Saps). This review comprehensively explores the multifaceted roles of Saps, highlighting their importance in biofilm formation, tissue invasion through the degradation of extracellular matrix proteins and components of the coagulation cascade, modulation of host immune responses via impairment of neutrophil and monocyte/macrophage functions, and their contribution to antifungal resistance. Additionally, the diagnostic challenges associated with Candida infections and the potential of Saps as biomarkers were discussed. Furthermore, we examined the prospects of developing vaccines based on Saps and the use of protease inhibitors as adjunctive therapies for candidiasis. Given the complex biology of Saps and their central role in Candida pathogenicity, a multidisciplinary approach may pave the way for innovative diagnostic strategies and open new opportunities for innovative clinical interventions against candidiasis.

Synthesis of bio-stabilized silver nanoparticles using Roccella montagnei, their anticandidal capacities & potential to inhibit the virulence factors in fluconazole-resistant Candida albicans

Candida species is the causative agent in approximately 80% of invasive mycoses and drug-resistant Candida albicans is among the four strains of 'critical priority group' framed by WHO. Lichens are endowed with some rare phytochemicals and a plethora of therapeutics viz. antifungal capacities of Roccella montagnei. Biosynthesis of silver nanoparticles (AgNPs) using lichen could offer an eco-friendly, and cost-effective alternative against emerging 'microbial resistance.' Therefore, the objective was to biosynthesize silver nanoparticles (Rm-AgNPs) using a Hydro-alcoholic (1:1) extract of R. montagnei to develop a potent anticandidal agent against Fluconazole-resistant C. albicans NBC099. UV-Spectroscopy identified AgNPs specific-peak of Rm-AgNPs at 420-440 nm and FTIR revealed the presence of amines, alcohol, aromatic compounds, and acids. SEM and TEM analysis indicated that Rm-AgNPs are spherical shaped with a size range of 10-50 nm. Zetasizer analysis indicated that particles are highly stable and have a mean hydrodynamic diameter of 116 nm with a zeta potential charge of - 41 mV. XRD analysis suggested face centered cubic crystal lattice structure. Results indicated that Rm-AgNPs strongly inhibited the growth of NBC099 at a minimum inhibitory concentration (IC50) of ≤ 15 µg. C. albicans culture treated with Rm-AgNPs at concentrations below IC50, down-regulates the production of different virulence factors in NBC099, viz. hyphal formation (> 85%), biofilms production (> 80%), phospholipase, esterase, proteinase activity. The apoptosis assay demonstrated the Rm-AgNPs induced apoptosis in NBC099 cells via oxidative stress. Interestingly, Rm-AgNPs showed negligible cytotoxicity (< 6%) in murine RAW 246.7 macrophage cells at a concentration above 15 µg/mL. Therefore, Rm-AgNPs have been offered as an anti-candida alternative that can be utilized to improve the efficacy of already available medications.

Applications of Green Synthesized Metal Nanoparticles - a Review

Green nanotechnology is an emerging field of science that focuses on the production of nanoparticles by living cells through biological pathways. This topic plays an extremely imperative responsibility in various fields, including pharmaceuticals, nuclear energy, fuel and energy, electronics, and bioengineering. Biological processes by green synthesis tools are more suitable to develop nanoparticles ranging from 1 to 100 nm compared to other related methods, owing to their safety, eco-friendliness, non-toxicity, and cost-effectiveness. In particular, the metal nanoparticles are synthesized by top-down and bottom-up approaches through various techniques like physical, chemical, and biological methods. Their characterization is very vital and the confirmation of nanoparticle traits is done by various instrumentation analyses such as UV-Vis spectrophotometry (UV-Vis), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), atomic force microscopy (AFM), annular dark-field imaging (HAADF), and intracranial pressure (ICP). In this review, we provide especially information on green synthesized metal nanoparticles, which are helpful to improve biomedical and environmental applications. In particular, the methods and conditions of plant-based synthesis, characterization techniques, and applications of green silver, gold, iron, selenium, and copper nanoparticles are overviewed.

The Antimicrobial Applications of Nanoparticles in Veterinary Medicine: A Comprehensive Review

Nanoparticles (NPs) are nanoscaled particles sized from 1-100 nm, which can be composed of inorganic or organic compounds. NPs have distinctive morphology, size, structure, and surface features, which give them specific properties. These particular attributes make them interesting for biological and medical applications. Due to these characteristics, researchers are studying the possible aptness of numerous nanoparticles in veterinary medicine, such as the capacity to act as a drug delivery system. The use of these NPs as a possible bactericidal or bacteriostatic medication has been studied against different bacteria, especially multiresistant strains and the ones that cause mastitis disease. The antibiofilm property of these nanostructures has also already been proved. The antiviral activity has also been shown for some important viral animal diseases; the antifungal activity had been demonstrated against both pathogenic and mycotoxigenic species. Therefore, this review aimed to elucidate the main clinical and preventive veterinary applications of inorganic and organic nanoparticles.

Biosynthesis and Characterization of Silver Nanoparticles from the Extremophile Plant Aeonium haworthii and Their Antioxidant, Antimicrobial and Anti-Diabetic Capacities

The present paper described the first green synthesis of silver nanoparticles (AgNPs) from the extremophile plant Aeonium haworthii. The characterization of the biosynthesized silver nanoparticles was carried out by using UV-Vis, FTIR and STM analysis. The antioxidant, antidiabetic and antimicrobial properties were also reported. The newly described AgNPs were spherical in shape and had a size of 35-55 nm. The lowest IC50 values measured by the DPPH assay indicate the superior antioxidant behavior of our AgNPs as opposed to ascorbic acid. The silver nanoparticles show high antidiabetic activity determined by the inhibitory effect of α amylase as compared to the standard Acarbose. Moreover, the AgNPs inhibit bacterial growth owing to a bactericidal effect with the MIC values varying from 0.017 to 1.7 µg/mL. The antifungal action was evaluated against Candida albicans, Candida tropicalis, Candida glabrata, Candida sake and non-dermatophytic onychomycosis fungi. A strong inhibitory effect on Candida factors' virulence was observed as proteinase and phospholipase limitations. In addition, the microscopic observations show that the silver nanoparticles cause the eradication of blastospores and block filamentous morphogenesis. The combination of the antioxidant, antimicrobial and antidiabetic behaviors of the new biosynthesized silver nanoparticles highlights their promising use as natural phytomedicine agents.

Biosynthesis of Gold Nanoparticles and Its Effect against Pseudomonas aeruginosa

Antimicrobial resistance has posed a serious health concern worldwide, which is mainly due to the excessive use of antibiotics. In this study, gold nanoparticles synthesized from the plant Tinospora cordifolia were used against multidrug-resistant Pseudomonas aeruginosa. The active components involved in the reduction and stabilization of gold nanoparticles were revealed by gas chromatography-mass spectrophotometry(GC-MS) of the stem extract of Tinospora cordifolia. Gold nanoparticles (TG-AuNPs) were effective against P. aeruginosa at different concentrations (50,100, and 150 µg/mL). TG-AuNPs effectively reduced the pyocyanin level by 63.1% in PAO1 and by 68.7% in clinical isolates at 150 µg/mL; similarly, swarming and swimming motilities decreased by 53.1% and 53.8% for PAO1 and 66.6% and 52.8% in clinical isolates, respectively. Biofilm production was also reduced, and at a maximum concentration of 150 µg/mL of TG-AuNPs a 59.09% reduction inPAO1 and 64.7% reduction in clinical isolates were observed. Lower concentrations of TG-AuNPs (100 and 50 µg/mL) also reduced the pyocyanin, biofilm, swarming, and swimming. Phenotypically, the downregulation of exopolysaccharide secretion from P. aeruginosa due to TG-AuNPs was observed on Congo red agar plates.

Green Synthesis of Silver Nanoparticles from Camellia sinensis and Its Antimicrobial and Antibiofilm Effect against Clinical Isolates

The green synthesis method of was used for the synthesis of silver nanoparticles using Camellia sinensis (green tea). The Camellia sinensis silver nanoparticles (CS-AgNPs) were characterized using different techniques, including UV-Vis (ultra violet-visible), SEM (scanning electron microscopy), TEM (transmission electron microscopy), and XRD (X-ray diffraction). The average size of the CS-AgNPs was 52 nm, according to TEM. The CS-AgNPs showed excellent antibacterial and antifungal activity. The MIC (minimum inhibitory concentration) against bacterial isolates varied from 31.25 to 62.5 µg/mL, whereas for fungal isolates, the MIC varied from 125 to 250 µg/mL. The presence of a zone in the well diffusion assay showed the antimicrobial nature of CS-AgNPs. Further, CLSM (confocal laser scanning microscopy) showed that CS-AgNPs possess antibiofilm activity. The interaction of CS-AgNPs with the Candidal cells was analyzed using TEM, and it was revealed that CS-AgNPs entered the cell and disrupted the cell machinery.

Hydrothermal assisted biogenic synthesis of silver nanoparticles: A potential study on virulent candida isolates from COVID-19 patients

Till now the exact mechanism and effect of biogenic silver nanoparticles on fungus is an indefinable question. To focus on this issue, the first time we prepared hydrothermal assisted thyme coated silver nanoparticles (T/AgNPs) and their toxic effect on Candida isolates were determined. The role of thyme (Thymus Vulgaris) in the reduction of silver ions and stabilization of T/AgNPs was estimated by Fourier transforms infrared spectroscopy, structure and size of present silver nanoparticles were detected via atomic force microscopy as well as high-resolution transmission electron microscopy. The biological activity of T/AgNPs was observed against Candida isolates from COVID-19 Patients. Testing of virulence of Candida species using Multiplex PCR. T/AgNPs proved highly effective against Candida albicans, Candida kruzei, Candida glabrata and MIC values ranging from 156.25 to 1,250 μg/mL and MFC values ranging from 312.5 to 5,000 μg/mL. The structural and morphological modifications due to T/AgNPs on Candida albicans were detected by TEM. It was highly observed that when Candida albicans cells were subjected to 50 and 100 μg/mL T/AgNPs, a remarkable change in the cell wall and cell membrane was observed.

Synthesis and Characterization of Novel Sprayed Ag-Doped Quaternary Cu2MgSnS4 Thin Film for Antibacterial Application

In this work, the effects of silver doping with different Ag/(Ag + Cu) ratios (i.e., 2%, 5% and 10% at.% in the spray solution) on the structural, morphological, optical, electrical and antibacterial properties of Cu₂MgSnS₄ (CMTS) thin film grown by spray pyrolysis have been studied. The X-ray diffraction (XRD) and selected area electron diffraction (SAED) results have shown that the kesterite phase of CMTS thin films has a maximum crystallite size of about 19.60 nm for 5% Ag/(Ag + Cu). Scanning electron microscopy (SEM) images have shown spherical grain shapes. The transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) microscopy observations confirmed the intrinsic reticular planes of CMTS thin film with (112) as a preferred orientation and interplanar spacing value of 3.1 Å. The optical properties showed high absorbance and an absorption coefficient of about 10⁴ cm^-1 in the visible region with an optical band gap energy of 1.51 eV. Impedance analysis spectroscopy demonstrated good electrical properties of the CMTS film obtained using 5% Ag/(Ag + Cu). The antibacterial activity of the undoped and Ag-doped particles of CMTS obtained using 5% Ag/(Ag + Cu) against different strains of pathogenic bacteria was tested using the agar well diffusion method. These results showed a significant antibacterial activity of the Ag-doped CMTS particle, which was much higher than the undoped CMTS particles. These experimental findings may open new practices for the Ag-doped CMTS compound, especially the one obtained using 5% Ag/(Ag + Cu), in antibacterial application.

Biosynthesis of silver nanoparticles from Syzygium cumini leaves and their potential effects on odontogenic pathogens and biofilms

This study analyzed the antimicrobial and antibiofilm action and cytotoxicity of extract (HEScL) and silver nanoparticles (AgNPs-HEScL) from Syzygium cumini leaves. GC–MS, UV–Vis, EDX, FEG/SEM, DLS and zeta potential assays were used to characterize the extract or nanoparticles. Antimicrobial, antibiofilm and cytotoxicity analyses were carried out by in vitro methods: agar diffusion, microdilution and normal oral keratinocytes spontaneously immortalized (NOK-SI) cell culture. MICs of planktonic cells ranged from 31.2–250 (AgNPs-HEScL) to 1,296.8–10,375 μg/ml (HEScL) for Actinomyces naeslundii, Fusobacterium nucleatum, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus mutans, Streptococcus oralis, Veillonella dispar, and Candida albicans. AgNPs-HEScL showed antibiofilm effects (125–8,000 μg/ml) toward Candida albicans, Streptococcus mutans and Streptococcus oralis, and Staphylococcus aureus and Staphylococcus epidermidis. The NOK-SI exhibited no cytotoxicity when treated with 32.8 and 680.3 μg/ml of AgNPs-HEScL and HEScL, respectively, for 5 min. The data suggest potential antimicrobial and antibiofilm action of HEScL, and more specifically, AgNPs-HEScL, involving pathogens of medical and dental interest (dose-, time- and species-dependent). The cytotoxicity of HEScL and AgNPs-HEScL detected in NOK-SI was dose- and time-dependent. This study presents toxicological information about the lyophilized ethanolic extract of S. cumini leaves, including their metallic nanoparticles, and adds scientific values to incipient studies found in the literature.

Silver Nanoparticles Prepared Using Encephalartos laurentianus De Wild Leaf Extract Have Inhibitory Activity against Candida albicans Clinical Isolates

Candida albicans is a major human opportunistic pathogen causing infections, which range from cutaneous to invasive systemic infections. Herein, the antifungal and anti-biofilm potential of silver nanoparticles (AgNPs) green synthesized in the presence of Encephalartos laurentianus leaf extract (ELLE) were investigated. The bioactive chemicals of ELLE, including phenolics, flavonoids, and glycosides were identified and quantified for the first time. AgNPs showed minimum inhibitory concentration (MIC) values against C. albicans clinical isolates ranging from 8 to 256 µg/mL. In addition, AgNPs significantly decreased biofilm formation. The impact of AgNPs on the expression of the genes encoding biofilm formation was assessed using qRT-PCR. AgNPs had a beneficial role in the macroscopic wound healing, and they resulted in complete epithelization without any granulation tissue or inflammation. Treatment with AgNPs resulted in negative immunostaining of tumor necrosis factor-α. The levels of the inflammation markers, interleukin-6 and interleukin-1β, significantly decreased (p < 0.05) in the AgNPs-treated group. There was also a pronounced increase in the gene expression of fibronectin and platelet-derived growth factor in the wound tissues. Thus, AgNPs synthesized using ELLE may be a promising antifungal and wound healing agent.

Characterization of nanomaterials synthesized from Spirulina platensis extract and their potential antifungal activity

Nowadays, fungal infections increase, and the demand of novel antifungal agents is constantly rising. In the present study, silver, titanium dioxide, cobalt (II) hydroxide and cobalt (II,III) oxide nanomaterials have been synthesized from Spirulina platensis extract. The synthesis mechanism has been studied using GCMS and FTIR thus confirming the involvement of secondary metabolites, mainly amines. The obtained products have been analysed using XRD, SEM, TGA and zeta potential techniques. The findings revealed average crystallite size of 15.22 nm with 9.72 nm for oval-shaped silver nanoparticles increasing to 26.01 nm and 24.86 nm after calcination and 4.81 nm for spherical-shaped titanium dioxide nanoparticles which decreased to 4.62 nm after calcination. Nanoflake shape has been observed for cobalt hydroxide nanomaterials and for cobalt (II, III) oxide with crystallite size of 3.52 nm and 13.28 nm, respectively. Silver nanoparticles showed the best thermal and water dispersion stability of all the prepared structures. Once subjected to three different Candida species (C. albicans, C. glabrata, and C. krusei) silver nanoparticles and cobalt (II) hydroxide nanomaterials showed strong antifungal activity at 50 μg/mL with minimum inhibitory concentration (MIC) values. After light exposition, MIC values for nanomaterials decreased (to 12.5 μg/mL) for C. krusei and increased (100 μg/mL) for C. albicans and C. glabrata.

Antimicrobial Effect of Extracellular Vesicles Derived From Human Oral Mucosal Epithelial Cells on Candida albicans

Candida albicans (C. albicans) is a commensal microorganism that colonizes the mucosal surfaces of healthy individuals. Changes in the host or environment can lead to overgrowth of C. albicans and infection of the host. Extracellular vesicles (EVs) are released by almost all cell types and play an increasingly recognized role in fighting microbial infection. The aim of the present study was to assess whether EVs derived from human oral mucosal epithelial (Leuk-1) cells can suppress the growth and invasion of C. albicans. The in vitro efficacy of Leuk-1-EVs against C. albicans was assessed by optical microscopy, laser scanning confocal microscopy, scanning electron microscopy, and transmission electron microscopy. The germ tube formation rate, the percentage of hyphae and the microcolony optical density were also used to analyze the growth of C. albicans in a coculture model with Leuk-1 cells and EVs or after inhibition of the secretion of EVs. A mouse model of oral candidiasis was established and submucosal injection of Leuk-1-EVs in the tongue was performed. Macroscopic observation, H&E staining, PAS staining, and scanning electron microscopy were used to assess antifungal effects of Leuk-1-EVs in vivo. The in vitro results showed that the growth of C. albicans was inhibited and that the morphology and ultrastructure were changed following Leuk-1-EVs treatment. The in vivo results exhibited that white lesions of the tongue, C. albicans infection, and oral mucosal inflammation of the infected mice were significantly alleviated after Leuk-1-EVs treatment. We thus reveal an antifungal capability of EVs derived from oral epithelial cells against C. albicans that is mediated by direct damage effects and potential synergy between EVs and human oral mucosal epithelial cells. This finding offers an intriguing, previously overlooked method of antifungal defense against C. albicans.

Therapeutic Effect of Green Synthesized Silver Nanoparticles Using Erodium glaucophyllum Extract against Oral Candidiasis: In Vitro and In Vivo Study

Oral candidiasis (OC) is a fungal infection caused by an opportunistic fungi Candida albicans, which is found in the normal flora of healthy people. In this study, we examined the anti-candidal effect of green synthesized silver nanoparticles using leaf extract of Erodium glaucophyllum (EG-AgNPs) against C. albicans in vitro and in vivo. EG-AgNPs were synthesized for the first time using E. glaucophyllum extract and characterized by imaging (transmission electron microscopy (TEM), UV-VIS spectroscopy, zeta potential, X-ray diffraction (XRD), Energy dispersive x-ray analysis (EDX), and Fourier transform infrared spectroscopy (FTIR). A mouse model of OC was used for in vivo study. The agar well diffusion method showed the anti-candidal activity of EG-AgNPs against C. albicans with MIC 50 µg/mL. EG-AgNPs inhibited the dimorphic transition of C. albicans and suppressed the formation of biofilm by 56.36% and 52%, respectively. Additionally, EG-AgNPs significantly inhibited the production of phospholipases and proteinases by 30% and 45%, respectively. EG-AgNPs cause cytoplasm disintegration and deterioration of cell wall as imaged by SEM and TEM. Interestingly, EG-AgNPs did not display any cytotoxicity on the human gingival fibroblast-1 HGF-1 cell line at MIC concentrations. Topical treatment of the tongue of the OC mouse model with EG-AgNPs showed significant reduction in candidal tissue invasion, less inflammatory changes, and no tissue modification, in association with marked low scare and hyphal counts as compared to control group. In conclusion, our data demonstrated the potent inhibitory action of EG-AgNPs on the growth and morphogenesis of C. albicans in vitro and in vivo. Thus, EG-AgNPs represent a novel plausible therapeutic approach for treatment of OC.

First Report of the Biosynthesis and Characterization of Silver Nanoparticles Using Scabiosa atropurpurea subsp. maritima Fruit Extracts and Their Antioxidant, Antimicrobial and Cytotoxic Properties

Candida and dermatophyte infections are difficult to treat due to increasing antifungal drugs resistance such as fluconazole, as well as the emergence of multi-resistance in clinical bacteria. Here, we first synthesized silver nanoparticles using aqueous fruit extracts from Scabiosa atropurpurea subsp. maritima (L.). The characterization of the AgNPs by means of UV, XRD, FTIR, and TEM showed that the AgNPs had a uniform spherical shape with average sizes of 40–50 nm. The biosynthesized AgNPs showed high antioxidant activity when investigated using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) and ferric reducing antioxidant power (FRAP) assays. The AgNPs displayed strong antibacterial potential expressed by the maximum zone inhibition and the lowest MIC and MBC values. The AgNPs revealed a significant antifungal effect against the growth and biofilm of Candida species. In fact, the AgNPs were efficient against Trichophyton rubrum, Trichophyton interdigitale, and Microsporum canis. The antifungal mechanisms of action of the AgNPs seem to be due to the disruption of membrane integrity and a reduction in virulence factors (biofilm and hyphae formation and a reduction in germination). Finally, the silver nanoparticles also showed important cytotoxic activity against the human multiple myeloma U266 cell line and the human breast cancer cell line MDA-MB-231. Therefore, we describe new silver nanoparticles with promising biomedical application in the development of novel antimicrobial and anticancer agents.

Green synthesis of silver nanoparticles using mixed leaves aqueous extract of wild olive and pistachio: characterization, antioxidant, antimicrobial and effect on virulence factors of Candida

In this study, a successfully rapid, simple approach was applied for biosynthesis of silver nanoparticles AgNPs using for the first time the mixed leaves extract of Olea europaea subsp. europaea var. sylvestris and Pistacia lentiscus from natural association aimed to enhance their antimicrobial potential. The plant extract acts both as reducing and capping agents. When the aqueous extract was added to AgNO₃ solution, the color was changed from pale to yellow to brown indicating the reduction of Ag ions and synthesis of silver nanoparticles (AgNPs) without any solvent or hazardous reagents. The green synthesized AgNPs were characterized by UV-Vis spectrophotometer, FTIR spectrum and the X-ray crystallography. The AgNPs showed superior antioxidant activity measured by DPPH, Ferric Antioxidant Reducing Power (FRAP) as well as the total antioxidant activity methods. Moreover, the analysis of phytochemical constituents including flavonoids, tannins, alkaloids and total polyphenols contents mentioned the most richness of the silver nanoparticles compared to plant extract. The new synthesized AgNPs demonstrated the bactericidal and fungicidal effects against all the tested bacterial and fungal strains and found to limit the spore germination of filamentous fungi. AgNPs also gave an anti-biofilm activity and synergistic effect with the conventional antibiotic's drugs. Here we firstly describe the silver nanoparticles effect on virulence factors of Candida species by reduction of enzymes like proteinase and phospholipase, inhibition of morphogenesis of Candida albicans cells. This natural product, acquiring these properties, should be promoted to be used in pharmaceutical and medical industries in future.

Effect of Silver Nanoparticles (AgNPs) on Candida Albicans, Candida Dubliniensis, and Candida Guilliermondii

Background:

Candida species are the most important fungal pathogens and are sometimes considered the fourth most common cause of infection in hospitals. Today, research needs to be conducted on the antifungal effect of silver nanoparticles (AgNPs) due to toxicity, side effects, and drug interactions of antifungal chemical drugs.

Objective:

Therefore, this study was done to evaluate the antifungal activity of AgNPs on Candida albicans, Candida dubliniensis, and Candida guilliermondii.

Methodology:

Antifungal activity of AgNPs on Candida albicans, Candida dubliniensis, and Candida guilliermondii was assessed by agar and macrodilution diffusion methods in an in-vitro investigation. Structural changes were investigated by scanning electron microscope (SEM). Then, the obtained data were evaluated by SPSS statistical software.

Results:

Based on the results, the mean diameter of growth inhibition halos by AgNPs was equal to 20, 20.2, and 40.7mm for Candida albicans, Candida dubliniensis, and Candida guilliermondii, respectively. The minimum inhibitory concentrations (MIC) equal 62.50, 31.25, and 15.62 mg/ml for Candida albicans, Candida dubliniensis, and Candida guilliermondii, respectively. The minimum fungicidal concentrations (MFC) were equal to 125, 62.50, and 31.25 mg/ml for Candida albicans, Candida dubliniensis, and Candida guilliermondii, respectively.

Conclusion:

Our results revealed that AgNPs inhibit the growth of Candida albicans, Candida dubliniensis, and Candida guilliermondii. SEM observations also showed that NPs disrupted cell membrane/wall. Changes in yeast levels from smooth to uneven were also observed.

Green approaches for the synthesis of metal and metal oxide nanoparticles using microbial and plant extracts

Green synthesis approaches are gaining significance as promising routes for the sustainable preparation of nanoparticles, offering reduced toxicity towards living organisms and the environment. Nanomaterials produced by green synthesis approaches can offer additional benefits, including reduced energy inputs and lower production costs than traditional synthesis, which bodes well for commercial-scale production. The biomolecules and phytochemicals extracted from microbes and plants, respectively, are active compounds that function as reducing and stabilizing agents for the green synthesis of nanoparticles. Microorganisms, such as bacteria, yeasts, fungi, and algae, have been used in nanomaterials' biological synthesis for some time. Furthermore, the use of plants or plant extracts for metal and metal-based hybrid nanoparticle synthesis represents a novel green synthesis approach that has attracted significant research interest. This review discusses various biosynthesis approaches via microbes and plants for the green preparation of metal and metal oxide nanoparticles and provides insights into the molecular aspects of the synthesis mechanisms and biomedical applications. The use of agriculture waste as a potential bioresource for nanoparticle synthesis and biomedical applications of biosynthesized nanoparticles is also discussed.

Antibiofilm Activities of Biogenic Silver Nanoparticles Against Candida albicans

Biofilms are microbial colonies that are encased in an organic polymeric matrix and are resistant to antimicrobial treatments. Biofilms can adhere to both biotic and abiotic surfaces, allowing them to colonize medical equipment such as urinary and intravenous catheters, mechanical heart valves, endotracheal tubes, and prosthetic joints. Candida albicans biofilm is the major etiological cause of the pathogenesis of candidiasis in which its unobstructed growth occurs in the oral cavity; trachea, and catheters that progress to systemic infections in the worst scenarios. There is an urgent need to discover novel biofilm preventive and curative agents. In the present investigation, an effort is made to observe the role of cyanobacteria-derived AgNPs as a new antibiofilm agent with special reference to candidiasis. AgNPs synthesized through the green route using Anabaena variabilis cell extract were characterized by UV-visible spectroscopy. The nanoparticles were spherical in shape with 11-15 nm size and were monodispersed. The minimum inhibitory concentration (MIC) of AgNPs was obtained at 12.5 μg/mL against C. albicans. AgNPs 25 μg/mL showed 79% fungal cell membrane permeability and 22.2% ROS production. AgNPs (25 μg/mL) also facilitated 62.5% of biofilm inhibition and degradation. Therefore, AgNPs could be considered as a promising antifungal agent to control biofilm produced by C. albicans.

Green approaches for the synthesis of metal and metal oxide nanoparticles using microbial and plant extracts

Green synthesis approaches are gaining significance as promising routes for the sustainable preparation of nanoparticles, offering reduced toxicity towards living organisms and the environment.

OUP accepted manuscript

Candida auris is an emerging, multi drug resistant fungal pathogen that has caused infectious outbreaks in over 45 countries since its first isolation over a decade ago, leading to in-hospital crude mortality rates as high as 72%. The fungus is also acclimated to disinfection procedures and persists for weeks in nosocomial ecosystems. Alarmingly, the outbreaks of C. auris infections in Coronavirus Disease-2019 (COVID-19) patients have also been reported. The pathogenicity, drug resistance and global spread of C. auris have led to an urgent exploration of novel, candidate antifungal agents for C. auris therapeutics. This narrative review codifies the emerging data on the following new/emerging antifungal compounds and strategies: antimicrobial peptides, combinational therapy, immunotherapy, metals and nano particles, natural compounds, and repurposed drugs. Encouragingly, a vast majority of these exhibit excellent anti- C. auris properties, with promising drugs now in the pipeline in various stages of development. Nevertheless, further research on the modes of action, toxicity, and the dosage of the new formulations are warranted. Studies are needed with representation from all five C. auris clades, so as to produce data of grater relevance, and broader significance and validity.

Biosynthesis of Silver Chloride Nanoparticles by Rhizospheric Bacteria and Their Antibacterial Activity against Phytopathogenic Bacterium Ralstonia solanacearum

Ralstonia solanacearum is the most destructive pathogen, causing bacterial wilt disease of eggplant. The present study aimed to develop green synthesis and characterization of silver chloride nanoparticles (AgCl-NPs) by using a native bacterial strain and subsequent evaluation of their antibacterial activity against R. solanacearum. Here, a total of 10 bacterial strains were selected for the biosynthesis of AgCl-NPs. Among them, the highest yield occurred in the synthesis of AgCl-NPs using a cell-free aqueous filtrate of strain IMA13. Ultrastructural observation revealed that the AgCl-NPs were spherical and oval with smooth surfaces and 5-35 nm sizes. XRD analysis studies revealed that these particles contained face-centered cubic crystallites of metallic Ag and AgCl. Moreover, FTIR analysis showed the presence of capping proteins, carbohydrates, lipids, and lipopeptide compounds and crystalline structure of AgCl-NPs. On the basis of phylogenetic analysis using a combination of six gene sequences (16S, gyrA, rpoB, purH, polC, and groEL), we identified strain IMA13 as Bacillus mojavensis. Three kinds of lipopeptide compounds, namely, bacillomycin D, iturin, and fengycin, forming cell-free supernatant produced by strain IAM13, were identified by MALDI-TOF mass spectrometry. Biogenic AgCl-NPs showed substantial antibacterial activity against R. solanacearum at a concentration of 20 µg/mL-1. Motility assays showed that the AgCl-NPs significantly inhibited the swarming and swimming motility (61.4 and 55.8%) against R. solanacearum. Moreover, SEM and TEM analysis showed that direct interaction of AgCl-NPs with bacterial cells caused rupture of cell wall and cytoplasmic membranes, as well as leakage of nucleic acid materials, which ultimately resulted in the death of R. solanacearum. Overall, these findings will help in developing a promising nanopesticide against phytopathogen plant disease management.

Effective Inhibition of Invasive Pulmonary Aspergillosis by Silver Nanoparticles Biosynthesized with Artemisia sieberi Leaf Extract

Aspergillus fumigatus is one of the most common fungal pathogens that can cause a diversity of diseases ranging from invasive pulmonary aspergillosis (IPA) and aspergilloma to allergic syndromes. In this study, we investigated the antifungal effect of silver nanoparticles biosynthesized with Artemisia sieberi leaf extract (AS-AgNPs) against A. fumigatus in vitro and in vivo. The biosynthesized AS-AgNPs were characterized by imaging (transmission electron microscopy (TEM)), UV-VIS spectroscopy, X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The microdilution method showed the antifungal activity of AS-AgNPs against A. fumigatus, with an MIC of 128 µg/mL. AS-AgNPs significantly inhibited the growth of hyphae in all directions, as imaged by SEM. Additionally, TEM on biofilm revealed invaginations of the cell membrane, a change in the vacuolar system, and the presence of multilamellar bodies within vacuoles. Interestingly, AS-AgNPs displayed low cytotoxicity on the A549 human lung cell line in vitro. Treatment of an invasive pulmonary aspergillosis (IPA) mouse model with AS-AgNPs demonstrated the potency of AS-AgNPs to significantly reduce lung tissue damage and to suppress the elevated levels of pro-inflammatory cytokines, tumor necrosis factor-alpha (TNF-α), interleukin-1 (IL-1), and interleukin-17 (IL-17). The therapeutic potential of AS-AgNPs was found to be due to their direct action to suppress the fungal burden and gliotoxin production in the lungs. In addition, AS-AgNPs reduced the oxidative stress in the lungs by increasing the enzymatic activities of catalase (CAT) and superoxide dismutase (SOD). Thus, our data indicate the biosynthesized AS-AgNPs as a novel antifungal alternative treatment against aspergillosis.

Anticandidal potentiality of biosynthesized and decorated nanometals with fucoidan

Candidagenus includes many hazardous and risky species that can develop resistance toward various antifungal types. Metals nanoparticles (NPs) possess powerful antimicrobial actions, but their potential human toxicity could limit their practices. The algal polysaccharide fucoidan (Fu) was extracted from the macro-brown algae,Cystoseira barbata, analyzed, and used for biosynthesizing nanoparticles of silver (Ag-NPs) and selenium (Se-NPs). The extracted Fu had elevated fucose levels (58.73% of total monosaccharides) and exhibited the main biochemical characteristic of customary Fu. The Fu biosynthesis of Ag-NPs and Se-NPs was achieved via facile direct protocol; Fu-synthesized NPs had 12.86 and 16.18 nm average diameters, respectively. The ultrastructure of Fu-synthesized NPs emphasized well-distributed and spherical particles that were embedded/capped in Fu as combined clusters. The Fu/Ag-NPs and Fu/Se-NPs anticandidal assessments, againstCandida albicans,Candida glabrata, andCandida parapsilosis, revealed that both NPs had powerful fungicidal actions against the examined pathogens. The ultrastructure imaging of subjectedC. albicansandC. parapsilosisto NPs revealed that Fu/Ag-NPs and Fu/Se-NPs triggered remarkable distortions, pore formation, and destructive lysis in cell surfaces within 10 h of exposure. The innovative usage ofC. barbataFu for Ag-NP and Se-NP synthesis and the application of their composites as powerful anticandidal agents, with minimized human toxicity, are concluded.

Biologically formed silver nanoparticles and in vitro study of their antimicrobial activities on resistant pathogens

Background and Objectives:

Silver nanoparticles (AgNPs) have been found to have multiple uses as antibacterial, antifungal and anti-biofilm agents because of their biological activities and safety. The present study was aimed to analyze the antimicrobial and anti-biofilm activities as well as the cytotoxic effect of AgNPs against different human pathogens.

Materials and Methods:

AgNPs were synthesized using cell free supernatants of Escherichia coli (ATCC 25922), Enterococcus faecalis (ATCC 19433), Pseudomonas aeruginosa (ATCC 27856), Enterobacter cloacae (ATCC 13047) and Penicillium oxalicum strain, then were analyzed using UV/Vis Spectral Analysis, Transmission electron microscopy (TEM). Scanning Electron Microscope (SEM) and Energy Dispersive-X-ray Spectroscopy (EDX) analysis. Antimicrobial activities of biosynthesized AgNPs were assessed with selected antimicrobial agents against multidrug resistant bacteria and candida. Anti-biofilm and cytotoxicity assays of these biosynthesized AgNPs were also done.

Results:

The synthesis of AgNPs were confirmed through observed color change and monitoring UV-Vis spectrum which showed homogeneous (little agglomeration) distribution of silver nanoparticles. TEM and SEM have shown that the particle size ranged from 13 to 34 (nm) with spherical shape and a high signal with EDX analysis. Antibacterial and antifungal efficacy of antibiotics and fluconazole were increased in combination with biosynthesized AgNPs against resistant bacteria and candida. Significant reduction in biofilm formation was found better with Penicillium oxalicum AgNPs against biofilm forming bacteria.

Conclusion:

Penicillium oxalicum has the best effect towards synthesizing AgNPs, for antimicrobial activities against resistant bacteria and candida, in addition to anti-biofilm activities against biofilm forming Staphylococcus aureus and E. coli and the safest cytotoxicity effect on (MRC-5) cell line.

Beta vulgaris Assisted Fabrication of Novel Ag-Cu Bimetallic Nanoparticles for Growth Inhibition and Virulence in Candida albicans

Beta vulgaris extract contains water-soluble red pigment betanin and is used as a food colorant. In this study, the biogenic Ag-Cu bimetallic nanoparticles were synthesized and characterized by different spectroscopic and microscopic techniques, including UV-Visible, FTIR, TEM. SEM-EDX, XRD, and TGA. Further, Ag-Cu bimetallic nanoparticles capped with Beta vulgaris biomolecules were evaluated for their antifungal activity against Candida albicans via targeting its major virulence factors, including adherence, yeast to hyphae transition, extracellular enzyme secretion, biofilm formation, and the expression of genes related to these pathogenic traits by using standard methods. C. albicans is an opportunistic human fungal pathogen that causes significant morbidity and mortality, mainly in immunocompromised patients. The current antifungal therapy is limited with various shortcomings such as host toxicity and developing multidrug resistance. Therefore, the development of novel antifungal agents is urgently required. Furthermore, NPs were screened for cell viability and cytotoxicity effect. Antifungal susceptibility testing showed potent antifungal activity of the Ag-Cu bimetallic NPs with a significant inhibitory effect on adherence, yeast to hyphae transition, extracellular enzymes secretion, and formation of biofilms in C. albicans at sub-inhibitory and inhibitory concentrations. The RT-qPCR results at an MIC value of the NPs exhibited a varying degree of downregulation in expression levels of virulence genes. Results also revealed the dose-dependent effect of NPs on cellular viability (up to 100%) using MUSE cell analyzer. Moreover, the low cytotoxicity effect of bimetallic NPs has been observed using haemolytic assay. The overall results indicated that the newly synthesized Ag-Cu bimetallic NPs capped with Beta vulgaris are proven to possess a potent anticandidal activity, by affecting the vital pathogenic factors of C. albicans.

Antimicrobial potential and in vitro cytotoxicity study of polyvinyl pyrollidone-stabilised silver nanoparticles synthesised from Lysinibacillus boronitolerans

The main emphasis herein is on the eco‐friendly synthesis and assessment of the antimicrobial potential of silver nanoparticles (AgNPs) and a cytotoxicity study. Silver nanoparticles were synthesised by an extracellular method using bacterial supernatant. Biosynthesised silver nanoparticles were characterised by UV‐vis spectroscopy, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy, dynamic light scattering, and zeta potential analysis. The synthesised silver nanoparticles exhibited a characteristic peak at 420 nm. TEM analysis depicted the spherical shape and approximately 20 nm size of nanoparticles. Silver nanoparticles carry a charge of −33.75 mV, which confirms their stability. Biogenic polyvinyl pyrrolidone‐coated AgNPs exhibited significant antimicrobial effects against all opportunistic pathogens (Gram‐positive and Gram‐negative bacteria, and fungi). Silver nanoparticles equally affect the growth of both Gram‐positive and Gram‐negative bacteria, with a maximum inhibition zone observed at 22 mm and a minimum at 13 mm against Pseudomonas aeruginosa and Fusarium graminearum, respectively. The minimum inhibitory concentration (MIC) of AgNPs against P. aeruginosa and Staphylococcus aureus was recorded at between 15 and 20 μg/ml. Synthesised nanoparticles exhibited a significant synergistic effect in combination with conventional antibiotics. Cytotoxicity estimates using C2C12 skeletal muscle cell line via 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT) test and lactate dehydrogenase assay were directly related to the concentration of AgNPs and length of exposure. On the basis of the MTT test, the IC50 of AgNPs for the C2C12 cell line was approximately 5.45 μg/ml concentration after 4 h exposure.

Silver Nanoparticles Biosynthesized with Spruce Bark Extract-A Molecular Aggregate with Antifungal Activity against Candida Species

Due to their high content of biomolecules, combined with silver's well known antimicrobial potential, silver nanoparticles biosynthesized using spruce bark (AgNP SBEs) demonstrate antibacterial and antioxidant activity, making them a versatile option for developing new antimicrobial agents that might be used for medical treatment or as adjuvants for the classical agents. This study aims to analyze if silver nanoparticles (AgNPs) mediated by spruce bark extract (SBE) and silver salts (AgNP SBE Acetate, AgNP SBE Nitrate) presents antifungal activity against five different Candida spp., synergistic activity with fluconazole, and if they interact with some virulence factors of C. albicans. AgNP SBEs presented MICs (minimum inhibitory concentrations) for all the five tested Candida spp. AgNP SBEs inhibited the growth of C. parapsilosis, C. krusei, and C. guilliermondii, exerted synergistic activity with fluconazole for C. parapsilosis and C. guilliermondii, and inhibited biofilm production for C. albicans, C. auris, and C. guilliermondii. MICs of AgNP SBE Acetate significantly inhibited the production of germ tubes of C. albicans. The expression of C. albicans SAP2 gene was down-regulated by the short-time treatment with MICs of AgNP SBE Acetate, while ALS3 and HSP70 genes were up-regulated by the AgNPs MICs. These results emphasize the potential of using the AgNP SBEs as treatments/adjuvants options, not only against the redundant C. albicans but also for the non-albicans Candida species (which are not as frequently involved in human pathologies, but, sometimes, can be more aggressive).

In Vitro Antifungal Activity of Silver Nanoparticles Biosynthesized with Beech Bark Extract

Biosynthesis is a green method for the synthesis of silver nanoparticles (AgNPs). This study aimed to assess the antifungal activity of two silver nanoparticle solutions, synthesized using beech bark extract (BBE) and acetate and nitrate silver salts (AgNP Acetate BBE and AgNP Nitrate BBE), their influence on biofilm production, their potential synergistic effects with fluconazole, on different Candida spp., and their influence on virulence factors of C. albicans (germ tube production, gene expression for ALS3, SAP2, HSP70). Both the AgNP BBEs presented different minimum inhibitory concentrations for all the studied Candida spp., but biofilm production was inhibited only for C. albicans and C. guilliermondii. The growth rates of all the studied Candida spp. were inhibited in the presence of both AgNP BBEs, except for C. auris. Synergistic activity was observed for C. parapsilosis and C. guilliermondii, for different combinations of fluconazole with both the AgNP BBEs. The germ tube production of C. albicans was slightly inhibited by the AgNP BBEs. Only AgNP Acetate BBE was able to down-regulate the expression of SAP2. Overall, we can conclude that, even if more studies are necessary, AgNPs synthesized with beech bark extract might be an interesting alternative to classic antifungal treatments.

Silver chitosan nanocomposites as a potential treatment for superficial candidiasis

Silver compounds are widely known for their antimicrobial activity, but can exert toxic effects to the host. Among the strategies to reduce its toxicity, incorporation into biopolymers has shown promising results. We investigated the green syntheses of silver nanoparticles (AgNPs) and their functionalization in a chitosan matrix (AgNPs@Chi) as a potential treatment against Candida spp. Inhibitory concentrations ranging between 0.06 and  1 μg/ml were observed against distinct Candida species. Nanocomposite-treated cells displayed cytoplasmic degeneration and a cell membrane and wall disruption. Silver nanocomposites in combination with fluconazole and amphotericin B showed an additive effect when analyzed by the Bliss method. The low cytotoxicity displayed in mammalian cells and in the Galleria mellonella larvae suggested their potential use in vivo. When tested as a topical treatment against murine cutaneous candidiasis, silver nanocomposites reduced the skin fungal burden in a dose-response behavior and favored tissue repair. In addition, the anti-biofilm effect of AgNPs@Chi in human nail model was demonstrated, suggesting that the polymeric formulation of AgNPs does not affect antifungal activity even against sessile cells. Our results suggest that AgNPs@Chi seems to be a less toxic and effective topical treatment for superficial candidiasis.

LAY SUMMARY

This study demonstrated the efficacy of silver nanoparticles (AgNPs) in inhibiting the growth of Candida. AgNPs incorporated in chitosan displayed a reduced toxicity. Tests in infected mice showed the effectiveness of the treatment. AgNPs-chitosan could be an alternative to combat candidiasis.

Phytoproduct, Arabic Gum and Opophytum forsskalii Seeds for Bio-Fabrication of Silver Nanoparticles: Antimicrobial and Cytotoxic Capabilities

The application of biological materials in synthesizing nanoparticles has become significant issue in nanotechnology. This research was designed to assess biogenic silver nanoparticles (AgNPs) fabricated using two aqueous extracts of Acacia arabica (Arabic Gum) (A-AgNPs) and Opophytum forsskalii (Samh) seed (O-AgNPs), which were used as reducing and capping agents in the NPs development, respectively. The current study is considered as the first report for AgNP preparation using Opophytum forsskalii extract. The dynamic light scattering, transmission electron microscopy, and scanning electron microscopy were employed to analyze the size and morphology of the biogenic AgNPs. Fourier transform infrared (FTIR) spectroscopy and chromatography/mass spectrometry (GC-MS) techniques were used to identify the possible phyto-components of plant extracts. The phyto-fabricated NPs were assessed for their antibacterial activity and also when combined with some antibiotics against Staphylococcus aureus (Gram-positive) and Pseudomonas aeruginosa and Escherichia coli (Gram-negative) and their anticandidal ability against Candida albicans using an agar well diffusion test. Furthermore, cytotoxicity against LoVo cancer cell lines was studied. The results demonstrated the capability of the investigated plant extracts to change Ag+ ions into spherical AgNPs with average size diameters of 91 nm for the prepared O-AgNPs and 75 nm for A-AgNPs. The phyto-fabricated AgNPs presented substantial antimicrobial capabilities with a zone diameter in the range of 10-29.3 mm. Synergistic effects against all tested strains were observed when the antibiotic and phyto-fabricated AgNPs were combined and assessed. The IC50 of the fabricated O-AgNPs against LoVo cancer cell lines was 28.32 μg/mL. Ten and four chemical components were identified in Acacia arabica (Arabic Gum) and Opophytum forsskalii seed extracts, respectively, by GC-MS that are expected as NPs reducing and capping agents. Current results could lead to options for further research, such as investigating the internal mechanism of AgNPs in bacteria, Candida spp., and LoVo cancer cell lines as well as identifying specific molecules with a substantial impact as metal-reducing agents and biological activities.

Citral derivative activates cell cycle arrest and apoptosis signaling pathways in Candida albicans by generating oxidative stress

For combating life-threatening infections caused by Candida albicans there is an urgent requirement of new antifungal agents with a targeted activity and low host cytotoxicity. Manipulating the mechanistic basis of cell death decision in yeast may provide an alternative approach for future antifungal therapeutics. Herein, the effect of an active citral derivative (Cd1) over the physiology of cell death in C. albicans was assessed. The viability of C. albicans SC5314 cells was determined by broth microdilution assay. The crucial morphological changes and apoptotic markers in Cd1-exposed yeast cells were analyzed. Subsequently the results confirmed that Cd1 arrested growth and caused death in yeast cells. Furthermore, this molecule inhibited antioxidant enzymes that resulted in production of reactive oxygen species. DNA fragmentation and condensation, phosphatidylserine exposure at the outer leaflet of cell membrane, mitochondrial disintegration as well as accumulation of cells at G2/M phase of the cell cycle were recorded. Altogether, this derivative induced apoptotic-type cell death in C. albicans SC5314.

Suppression of hyphal formation and virulence of Candida albicans by natural and synthetic compounds

Candida albicans undergoes a morphological yeast-to-hyphal transition during infection, which plays a significant role in its pathogenesis. The filamentous morphology of the hyphal form has been identified as a virulence factor as it facilitates surface adherence, intertwining with biofilm, invasion, and damage to host tissues and organs. Hence, inhibition of filamentation in addition to biofilm formation is considered a viable strategy against C. albicans infections. Furthermore, a good understanding of the signaling pathways involved in response to environmental cues driving hyphal growth is also critical to an understanding of C. albicans pathogenicity and to develop novel therapies. In this review, first the clinical significance and transcriptional control of C. albicans hyphal morphogenesis are addressed. Then, various strategies employed to suppress filamentation, prevent biofilm formation, and reduce virulence are discussed. These strategies include the inhibition of C. albicans filament formation using natural or synthetic compounds, and their combination with other agents or nanoformulations.