Inhibitory Activity of Silver Nanoparticles Synthesized Using Lycopersicon Esculentum against Biofilm Formation in Candida Species

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.

Nanomaterial in controlling biofilms and virulence of microbial pathogens

The escalating threat of antimicrobial resistance (AMR) poses a grave concern to global public health, exacerbated by the alarming shortage of effective antibiotics in the pipeline. Biofilms, intricate populations of bacteria encased in self-produced matrices, pose a significant challenge to treatment, as they enhance resistance to antibiotics and contribute to the persistence of organisms. Amid these challenges, nanotechnology emerges as a promising domain in the fight against biofilms. Nanomaterials, with their unique properties at the nanoscale, offer innovative antibacterial modalities not present in traditional defensive mechanisms. This comprehensive review focuses on the potential of nanotechnology in combating biofilms, focusing on green-synthesized nanoparticles and their associated anti-biofilm potential. The review encompasses various aspects of nanoparticle-mediated biofilm inhibition, including mechanisms of action. The diverse mechanisms of action of green-synthesized nanoparticles offer valuable insights into their potential applications in addressing AMR and improving treatment outcomes, highlighting novel strategies in the ongoing battle against infectious diseases.

Antimicrobial and antioxidant potential of the silver nanoparticles synthesized using aqueous extracts of coconut meat (Cocos nucifera L)

Human pathogenic fungi and bacteria pose a huge threat to human life, accounting for high rates of mortality every year. Unfortunately, the past few years have seen an upsurge in multidrug resistance pathogens. Consequently, finding an effective alternative antimicrobial agent is of utmost importance. Hence, this study aimed to phytofabricate silver nanoparticles (AgNPs) using aqueous extracts of the solid endosperm of Cocos nucifera L, also known as coconut meat (Cm). Green synthesis is a facile, cost-effective and eco-friendly methods which has several benefits over other physical and chemical methods. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS). The Cm-AgNPs showed a UV-Vis peak at 435 nm and were crystalline and quasi-spherical, with an average size of 15 nm. The FTIR spectrum displayed functional groups of phenols, alkaloids, sugars, amines, and carbonyl compounds, which are vital in the reduction and capping of NPs. The antibacterial and anticandidal efficacy of the Cm-AgNPs was assessed by the agar-well diffusion method and expressed as a zone of inhibition (ZOI). Amongst all the test isolates, Staphylococcus epidermidis, Candida auris, and methicillin-resistant Staphylococcus epidermidis were more susceptible to the NPs with a ZOI of 26.33 ± 0.57 mm, 19.33 ± 0.57 mm, and 18 ± 0.76 mm. The MIC and MFC values for Candida spp. were higher than the bacterial test isolates. Scanning electron microscopic studies of all the test isolates at their MIC concentrations showed drastically altered cell morphology, indicating that the NPs could successfully cross the cell barrier and damage the cell integrity, causing cell death. This study reports the efficacy of Cm-AgNPs against several Candida and bacterial strains, which had not been reported in earlier studies. Furthermore, the synthesized AgNPs exhibited significant antioxidant activity. Thus, the findings of this study strongly imply that the Cm-AgNPs can serve as promising candidates for therapeutic applications, especially against multidrug-resistant isolates of Candida and bacteria. However, further investigation is needed to understand the mode of action and biosafety.

Exploring the biological application of Penicillium fimorum-derived silver nanoparticles: In vitro physicochemical, antifungal, biofilm inhibitory, antioxidant, anticoagulant, and thrombolytic performance

This study showed the anti-candida, biofilm inhibitory, antioxidant, anticoagulant, and thrombolytic properties of biogenic silver nanoparticles (AgNPs) fabricated by using the supernatant of Penicillium fimorum (GenBank accession number OQ568180) isolated from soil. The biogenic AgNPs were characterized by using different analytical techniques. A sharp surface plasmon resonance (SPR) peak of the colloidal AgNPs at 429.5 nm in the UV-vis spectrum confirmed the fabrication of nanosized silver particles. The broth microdilution assay confirmed the anti-candida properties of AgNPs with a minimum inhibitory concentration (MIC) of 4 μg mL^-1. In the next step, the protein and DNA leakage assays as well as reactive oxygen species (ROS) assay were performed to evaluate the possible anti-candida mechanisms of AgNPs representing an increase in the total protein and DNA of supernatant along with a climb-up in ROS levels in AgNPs-treated samples. Flow cytometry also confirmed a dose-dependent cell death in the AgNPs-treated samples. Further studies also confirmed the biofilm inhibitory performance of AgNPs against Candia albicans. The AgNPs at the concentrations of MIC and 4*MIC inhibited 79.68 ± 14.38% and 83.57 ± 3.41% of biofilm formation in C. albicans, respectively. Moreover, this study showed that the intrinsic pathway may play a significant role in the anticoagulant properties of AgNPs. In addition, the AgNPs at the concentration of 500 μg mL^-1, represented 49.27%, and 73.96 ± 2.59% thrombolytic and DPPH radical scavenging potential, respectively. Promising biological performance of AgNPs suggests these nanomaterials as a good candidate for biomedical and pharmaceutical applications.

Antibiofilm activity of silver nanoparticles biosynthesized using viticultural waste

Green methods have become vital for sustainable development of the scientific and commercial sphere; however, they can bring new challenges, including the need for detailed characterization and elucidation of efficacy of their products. In this study, green method of silver nanoparticles (AgNPs) production was employed using an extract from grapevine canes. The aim of the study was to contribute to the knowledge about biosynthesized AgNPs by focusing on elucidation of their antifungal efficiency based on their size and/or hypothesized synergy with bioactive substances from Vitis vinifera cane extract. The antifungal activity of AgNPs capped and stabilized with bioactive compounds was tested against the opportunistic pathogenic yeast Candida albicans. Two dispersions of nanoparticles with different morphology (characterized by SEM-in-STEM, DLS, UV-Vis, XRD, and AAS) were prepared by modification of reaction conditions suitable for economical production and their long-term stability monitored for six months was confirmed. The aims of the study included the comparison of the antifungal effect against suspension cells and biofilm of small monodisperse AgNPs with narrow size distribution and large polydisperse AgNPs. The hypothesis of synergistic interaction of biologically active molecules from V. vinifera extracts and AgNPs against both cell forms were tested. The interactions of all AgNPs dispersions with the cell surface and changes in cell morphology were imaged using SEM. All variants of AgNPs dispersions were found to be active against suspension and biofilm cells of C. albicans; nevertheless, surprisingly, larger polydisperse AgNPs were found to be more effective. Synergistic action of nanoparticles with biologically active extract compounds was proven for biofilm cells (MBIC₈₀ 20 mg/L of polydisperse AgNPs in extract), while isolated nanoparticles suspended in water were more active against suspension cells (MIC 20 mg/L of polydisperse AgNPs dispersed in water). Our results bring new insight into the economical production of AgNPs with defined characteristics, which were proven to target a specific mode of growth of significant pathogen C. albicans.

Investigation the effects of silver nanoparticles and gold nanoparticles on expression of bap and csu genes in biofilm formation of Acinetobacter baumannii

Background and Objectives

Acinetobacter baumannii is one of the main pathogens of the hospital and causes various infections. csu A/BABCDE involved in the initial surface attachment during biofilm formation and bap gene produces specific proteins at the cell surface that play a direct role in formation of biofilm and the infectivity of this bacterium. The aim of this study was to investigate the effect of silver nanoparticles and gold nanoparticles on the expression of bap and csu genes in the Acinetobacter baumannii biofilm formation.

Materials and Methods

The susceptibility test was performed to determine the MIC of silver nanoparticles, gold nanoparticles and gold-vancomycin nanoparticles performed by broth dilution method on A. baumannii strains. The ability of biofilms formation in strains treated by MIC of silver nanoparticles and gold-vancomycin nanoparticles were evaluated by microtiter plate method and A. baumannii ATCC19606 used as control. Expression of the csu and bap genes were determinded by measuring the cognate mRNA level by real-time PCR.

Results

In present study, gold nanoparticles could not prevent the growth and biofilm formation of A. baumannii strains. The MIC concentration of silver nanoparticles and vancomycin- gold nanoparticles were 6.25 μg/ml and 0.625 μg/ml respectively and MBC concenteration of nanoparticles for 70% of strain was 12.5 μg/ml and 1.25 μg/ml respectively. Real-time PCR and data analysis, determined that the expression of bap, csuC and csuE genes in A. baumannii strains treated with MIC concentration (6.25 μg/ml) of silver nanoparticles decreased compared to control groups. Also, the expression of csuC and csuE genes in strains treated with MIC concentration (0.625 μg/ml) of vancomycin -gold nanoparticles increased, however the expression of bap was decreased compared to the control groups.

Conclusion

Due to the inhibitory effect of silver nanoparticles and gold-vancomycin nanoparticles against A. baumannii biofilm formation and genes expression, they can probably be used for prevent of biofilm formation in medical instrument or can be use for treatment of infections with or without antibiotic.

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.

Phyto-fabricated Nanoparticles and Their Anti-biofilm Activity: Progress and Current Status

Biofilm is the self-synthesized, mucus-like extracellular polymeric matrix that acts as a key virulence factor in various pathogenic microorganisms, thereby posing a serious threat to human health. It has been estimated that around 80% of hospital-acquired infections are associated with biofilms which are found to be present on both biotic and abiotic surfaces. Antibiotics, the current mainstream treatment strategy for biofilms are often found to be futile in the eradication of these complex structures, and to date, there is no effective therapeutic strategy established against biofilm infections. In this regard, nanotechnology can provide a potential platform for the alleviation of this problem owing to its unique size-dependent properties. Accordingly, various novel strategies are being developed for the synthesis of different types of nanoparticles. Bio-nanotechnology is a division of nanotechnology which is gaining significant attention due to its ability to synthesize nanoparticles of various compositions and sizes using biotic sources. It utilizes the rich biodiversity of various biological components which are biocompatible for the synthesis of nanoparticles. Additionally, the biogenic nanoparticles are eco-friendly, cost-effective, and relatively less toxic when compared to chemically or physically synthesized alternatives. Biogenic synthesis of nanoparticles is a bottom-top methodology in which the nanoparticles are formed due to the presence of biological components (plant extract and microbial enzymes) which act as stabilizing and reducing agents. These biosynthesized nanoparticles exhibit anti-biofilm activity via various mechanisms such as ROS production, inhibiting quorum sensing, inhibiting EPS production, etc. This review will provide an insight into the application of various biogenic sources for nanoparticle synthesis. Furthermore, we have highlighted the potential of phytosynthesized nanoparticles as a promising antibiofilm agent as well as elucidated their antibacterial and antibiofilm mechanism.

Understanding the interactions between inorganic-based nanomaterials and biological membranes

The interactions between inorganic-based nanomaterials (NMs) and biological membranes are among the most important phenomena for developing NM-based therapeutics and resolving nanotoxicology. Herein, we introduce the structural and functional effects of inorganic-based NMs on biological membranes, mainly the plasma membrane and the endomembrane system, with an emphasis on the interface, which involves highly complex networks between NMs and biomolecules (such as membrane proteins and lipids). Significant efforts have been devoted to categorizing and analyzing the interaction mechanisms in terms of the physicochemical characteristics and biological effects of NMs, which can directly or indirectly influence the effects of NMs on membranes. Importantly, we summarize that the biological membranes act as platforms and thereby mediate NMs-immune system contacts. In this overview, the existing challenges and potential applications in the areas are addressed. A strong understanding of the discussed concepts will promote therapeutic NM designs for drug delivery systems by leveraging the NMs-membrane interactions and their functions.

Silver nanoparticles offer a synergistic effect with fluconazole against fluconazole-resistant Candida albicans by abrogating drug efflux pumps and increasing endogenous ROS

OBJECTIVES

A frequent emergence of drug resistance has been observed and posed great threat to global public health recently. This work aimed to investigate the potential synergistic effect and the underlying mechanisms of AgNPs-fluconazole combination more extensively through 2 clinically isolated fluconazole-resistant Candida albicans (C. albicans) strains.

METHODS

Antifungal properties of AgNPs and fluconazole alone or together against planktonic cells and biofilms were tested. Cellular and molecular targets associated with fluconazole resistance were monitored after AgNPs treatment. Antifungal potential of AgNPs-fluconazole combination was also explored in vivo using a mouse model of disseminated candidiasis. Tissue burden and survival rate were analyzed.

RESULTS

The results indicated that AgNPs worked synergistically with fluconazole against both planktonic cells of fluconazole-resistant C. albicans and biofilms formed <12 h. AgNPs treatment down-regulated ERG1, ERG11, ERG25, and CDR2, decreased membrane ergosterol levels and membrane fluidity, reduced membrane content of Cdr1p, Cdr2p, and thus efflux bump activity. The elevated ROS production was also a likely cause of the synergistic effect. In vivo, AgNPs and fluconazole combination significantly decreased the fungal burden and improved the survival rate of infected mice.

CONCLUSION

In conclusion, these results further confirm that AgNPs-fluconazole combination is a hopeful strategy for the treatment of fluconazole-resistant fungal infections.

Green Synthesis of Silver Nanoparticles Using the Lotus lalambensis Aqueous Leaf Extract and Their Anti-Candidal Activity against Oral Candidiasis

Oral candidiasis is widely spread in both humans and animals, which is caused mainly by Candida albicans. In this study, we aimed to biosynthesize silver nanoparticles (AgNPs) for the first time using the Lotus lalambensis Schweinf leaf extract (L-AgNPs) and investigated their anti-candidal potency alone or in combination with the leaf extract of L. lalambensis (L-AgNPs/LL) against C. albicans. The biosynthesized L-AgNPs were characterized by imaging (transmission electron microscopy, TEM), UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD). The results of the disk diffusion method showed the potent synergistic anti-candidal activity of L-AgNPs/LL (24 mm inhibition zone). L-AgNPs/LL completely inhibited the morphogenesis of C. albicans and suppressed the adhesion and the formation of the biofilm of C. albicans by 82.5 and 78.7%, respectively. Further, L-AgNPs/LL inhibited the production of antioxidant enzymes of C. albicans by 80%. SEM and TEM revealed deteriorations in the cell wall ultrastructure in L-AgNPs/LL-treated C. albicans. Interestingly, L-AgNPs/LL showed less than 5% cytotoxicity when examined with either the primary bone marrow derived mesenchymal stem cell (BMSCs) or MCF-7 cell line at MIC values of L-AgNPs/LL. In conclusion, we identified L-AgNPs/LL as a potential biosynthesized-based drug for oral candidiasis in humans and animals.

Candida albicans-The Virulence Factors and Clinical Manifestations of Infection

Candida albicans is a common commensal fungus that colonizes the oropharyngeal cavity, gastrointestinal and vaginal tract, and healthy individuals' skin. In 50% of the population, C. albicans is part of the normal flora of the microbiota. The various clinical manifestations of Candida species range from localized, superficial mucocutaneous disorders to invasive diseases that involve multiple organ systems and are life-threatening. From systemic and local to hereditary and environmental, diverse factors lead to disturbances in Candida's normal homeostasis, resulting in a transition from normal flora to pathogenic and opportunistic infections. The transition in the pathophysiology of the onset and progression of infection is also influenced by Candida's virulence traits that lead to the development of candidiasis. Oral candidiasis has a wide range of clinical manifestations, divided into primary and secondary candidiasis. The main supply of C. albicans in the body is located in the gastrointestinal tract, and the development of infections occurs due to dysbiosis of the residential microbiota, immune dysfunction, and damage to the muco-intestinal barrier. The presence of C. albicans in the blood is associated with candidemia-invasive Candida infections. The commensal relationship exists as long as there is a balance between the host immune system and the virulence factors of C. albicans. This paper presents the virulence traits of Candida albicans and clinical manifestations of specific candidiasis.

Antibacterial Activity of Green-Synthesized Silver Nanoparticles Using Areca catechu Extract against Antibiotic-Resistant Bacteria

In this work, the antibacterial activity of silver nanoparticles (AgNPs) synthesized using Areca catechu extracts against three species of antibiotic-susceptible and three species of resistant bacteria was investigated. The effects of this plant were more promising when compared with other medicinal plants tested. The hydrothermal extract of Areca catechu was mixed with silver nitrate to synthesize AgNPs. The synthesized particle characteristics were analyzed by UV–Vis spectrophotometry, scanning electron microscopy (SEM), dynamic light scattering (DLS), and Fourier-transform infrared spectroscopy (FT-IR). Minimum inhibitory concentration and minimum bactericidal concentration tests were conducted to confirm antibacterial activity and the results showed that AgNPs synthesized using Areca catechu extracts effectively inhibited the growth of bacterial species. Moreover, the SEM images of the bacterial species treated with AgNPs synthesized with Areca catechu extracts showed that clusters of AgNPs were attached to the surface of the bacterial cell wall, which could induce destruction of the cell membranes. The results suggest that AgNPs synthesized with Areca catechu extracts have the potential to treat antibiotic-resistant bacteria known as the major cause of nosocomial infections.

Dissecting the anti-biofilm potency of kappa-carrageenan capped silver nanoparticles against Candida species

Global antimicrobial crisis and advent of drug resistant fungal strains has substantially distressed disease management for clinicians. Biodegradable silver nanoparticles (AgNps) emerge as an excellent alternative remedial option. In the current study, the anti-biofilm activity of microwave irradiated kappa-carrageenan (CRG) capped AgNps against Candida albicans, and Candida glabrata was investigated in terms of their effect on reactive oxygen species (ROS) generation, cellular morphology, biochemical composition, and the activity of enzymes of extracellular matrix. Minimum inhibitory concentration and fungicidal concentration value of CRG-AgNps against both Candida spp. ranged between 400 and 500 μg/mL. The 80% of Candida biofilm was inhibited and eradicated by CRG-AgNps at a concentration of ~300 μg/mL. Microscopic studies indicate that CRG-AgNps caused morphological damage through membrane disruption and pore formation. Further, CRG-AgNps generated ROS in a concentration-dependent manner and modulated the composition of Candida biofilm ECM by increasing the carbohydrate and eDNA content. CRG-AgNps also significantly inactivated the hydrolytic enzymes, thus hindering the biofilm forming ability. In conclusion, all these results suggest that the CRG-AgNps are potential antifungal agents against Candida biofilms, and they inhibit/eradicate the fungal biofilms through multiple signalling mechanisms.