Synthesis, characterization, and in vitro activity against Candida spp. of fluconazole encapsulated on cationic and conventional nanoparticles of poly(lactic-co-glycolic acid)

Advancing cryptococcal treatment: The role of nanoparticles in mitigating antifungal resistance

Cryptococcus, a ubiquitous and formidable fungal pathogen, contributes to a substantial global disease burden, with nearly 250,000 cases and 181,000 fatalities attributed to cryptococcal meningitis annually worldwide. The invasive nature of Cryptococcus presents significant challenges in treatment and management, as it mostly affects vulnerable populations, including HIV patients, organ transplant recipients, pregnant women, and elderly individuals. Moreover, these difficulties are exacerbated by the development of antifungal resistance, which emphasizes the need for efficient control measures. In this context, research efforts focusing on infection control and novel therapeutic strategies become paramount. Nanoparticle-based therapies emerge as a solution, offering advanced antifungal properties and improved efficacy. Developing effective treatment options requires understanding the complex landscape of cryptococcal infections and the innovative potential of nanoparticle-based therapies. This review highlights the urgent need for novel strategies to combat the growing threat posed by antifungal resistance while offering insights into the intricate realm of cryptococcal infections, particularly focusing on the promising role of nanoparticle-based therapies.

Understanding fluconazole tolerance in Candida albicans: implications for effective treatment of candidiasis and combating invasive fungal infections

OBJECTIVES

Fluconazole (FLC) tolerant phenotypes in Candida species contribute to persistent candidemia and the emergence of FLC resistance. Therefore, making FLC fungicidal and eliminating FLC tolerance are important for treating invasive fungal diseases (IFDs) caused by Candida species. However, the mechanisms of FLC tolerance in Candida species remain to be fully explored.

METHODS

This review discusses the high incidence of FLC tolerance in Candida species and the importance of successfully clearing FLC tolerance in treating candidiasis. We further define and characterize FLC tolerance in C. albicans.

RESULTS

This review identifies global factors affecting FLC tolerance and suggest that FLC tolerance is a strategy of C. albicans response to FLC damage whose mechanism differs from FLC resistance.

CONCLUSIONS

This review highlights the significance of the cell membrane and cell wall integrity in FLC tolerance, guiding approaches to combat IFDs caused by Candida species..

A pH-tuned chitosan-PLGA nanocarrier for fluconazole delivery reduces toxicity and improves efficacy against resistant Candida

Fluconazole (FLZ) is a broad-spectrum antifungal used against Candida infections. Candida auris displays resistance to FLZ. Drug nanocarriers composed of natural (chitosan, C) or synthetic polymers (polylactide co-glycolide, PLGA) show improved drug characteristics, efficacy and reduction in toxicity. Here, C-PLGA nanoparticles (110 nm) were synthesized by coacervation method and loaded with FLZ, achieving ~8-wt% drug loading. The nanoformulation displayed pH-tuned slow sustained drug release (83 %) up to 5 d, at pH 4, while 34 % release occurred at pH 7.0. Fluorescent-tagged C-PLGA-NPs were localized on the Candida cell wall/membrane as seen by confocal microscopy. This resulted in ~1.9-fold reduced efflux of R6G dye as compared to bare drug treatment in Candida albicans and resistant C. auris. The nanoformulation showed a significant 16- and 64-fold (p < 0.0001) enhanced antifungal activity (MIC 5 and 2.5 μg/ml) against C. albicans and C. auris, respectively, as compared to FLZ. The nanoformulation showed highly effective antifungal activity in-vivo against C. albicans and C. auris. Moreover, the nephrotoxicity and hepatotoxicity was negligible. Thus, PLGA NPs-mediated fluconazole delivery can contribute to increased drug efficacy and to reduce the problem of fungal resistance.

Antifungal Encapsulated into Ligand-Functionalized Nanoparticles with High Specificity for Macrophages

Infectious diseases caused by intracellular microorganisms such as Histoplasma capsulatum represent a significant challenge worldwide. Drug encapsulation into functionalized nanoparticles (NPs) is a valuable alternative to improving drug solubility and bioavailability, preventing undesirable interactions and drug degradation, and reaching the specific therapeutic target with lower doses. This work reports on Itraconazole (ITZ) encapsulated into core-shell-like polymeric NPs and functionalized with anti-F4/80 antibodies for their targeted and controlled release into macrophages. Uptake assay on co-culture showed significant differences between the uptake of functionalized and bare NPs, higher with functionalized NPs. In vitro assays showed that F4/80-NPs with 0.007 µg/mL of encapsulated ITZ eliminated the H. capsulatum fungus in co-culture with macrophages effectively compared to the bare NPs, without any cytotoxic effect on macrophages after 24 h interaction. Furthermore, encapsulated ITZ modulated the gene expression of anti and pro-inflammatory cytokines (IL-1, INF-Y, IL-6 and IL-10) on macrophages. Additionally, the anti-F4/80 antibody-coating enhanced natural and adequate antifungal response in the cells, exerting a synergistic effect that prevented the growth of the fungus at the intracellular level. Functionalized NPs can potentially improve macrophage-targeted therapy, increasing NPs endocytosis and intracellular drug concentration.

Core-shell polycationic polyurea pharmadendrimers: new-generation of sustainable broad-spectrum antibiotics and antifungals

The efficacy of conventional antimicrobials is falling to critical levels and raising alarming concerns around the globe. In this scenery, engineered nanoparticles emerged as a solid strategy to fight growing deadly infections. Here, we show the in vitro and in vivo performance of pharmadendrimers, a novel class of engineered polyurea dendrimers that are synthetic mimics of antibacterial peptides, against a collection of both Gram-positive and Gram-negative bacteria and fungi. These nanobiomaterials are stable solids prepared by low-cost and green processes, display a dense positively charged core-shell, and are biocompatible and hemocompatible drugs. Mechanistic data, corroborated by coarse-grained molecular dynamics simulations, points towards a fast-killing mechanism via membrane disruption, triggered by electrostatic interactions. Altogether this study provides strong evidence and support for the future use of polyurea pharmadendrimers in antibacterial and antifungal nanotherapeutics.

Application of Fluconazole-Loaded pH-Sensitive Lipid Nanoparticles for Enhanced Antifungal Therapy

Cryptococcus neoformans is a yeast-like fungus that can cause the life-threatening disease cryptococcal meningitis. Numerous reports have shown increased resistance of this fungus against antifungal treatments, such as fluconazole (Fluc), contributing to an 80% global mortality rate. This work presents a novel approach to improve the delivery of the antifungal agent Fluc and increase the drug's targetability and availability at the infection site. Exploiting the acidic environment surrounding a C. neoformans infected site, we have developed pH-sensitive lipid nanoparticles (LNP) encapsulating Fluc to inhibit the growth of resistant C. neoformans. The LNP-Fluc delivery system consists of a neutral lipid monoolein (MO) and a novel synthetic ionizable lipid 2-morpholinoethyl oleate (O2ME). At neutral pH, because of the presence of O2ME, the nanoparticles are neutral and exhibit a liquid crystalline hexagonal nanostructure (hexosomes). At an acidic pH, they are positively charged with a cubic nanostructure (cubosomes), which facilitates the interaction with the negatively charged fungal cell wall. This interaction results in the MIC50 and MIC90 values of the LNP-Fluc being significantly lower than that of the free-Fluc control. Confocal laser scanning microscopy and scanning electron microscopy further support the MIC values, showing fungal cells exposed to LNP-Fluc at acidic pH were heavily distorted, demonstrating efflux of cytoplasmic molecules. In contrast, fungal cells exposed to Fluc alone showed cell walls mostly intact. This current study represents a significant advancement in delivering targeted antifungal therapy to combat fungal antimicrobial resistance.

Potent antifungal agents and use of nanocarriers to improve delivery to the infected site: A systematic review

There are four major classes of antifungals with the predominant mechanism of action being targeting of cell wall or cell membrane. As in other drugs, low solubility of these compounds has led to low bioavailability in target tissues. Enhanced drug dosages have effects such as toxicity, drug-drug interactions, and increased drug resistance by fungi. This article reviews the current state-of-the-art of antifungals, structure, mechanism of action, other usages, and toxic side effects. The emergence of nanoformulations to transport and uniformly release cargo at the target site is a boon in antifungal treatment. The article details research that lead to the development of nanoformulations of antifungals and potential advantages and avoidance of the lacunae characterizing conventional drugs. A range of nanoformulations based on liposomes, polymers are in various stages of research and their potential advantages have been brought out. It could be observed that under similar dosages, test models, and duration, nanoformulations provided enhanced activity, reduced toxicity, higher uptake and higher immunostimulatory effects. In most instances, the mechanism of antifungal activity of nanoformulations was similar to that of regular antifungal. There are possibilities of coupling multiple antifungals on the same nano-platform. Increased activity coupled with multiple mechanisms of action presents for nanoformulations a tremendous opportunity to overcome antifungal resistance. In the years to come, robust methods for the preparation of nanoformulations taking into account the repeatability and reproducibility in action, furthering the studies on nanoformulation toxicity and studies of human models are required before extensive use of nanoformulations as a prescribed drug.

Biodegradable polymers-based nanoparticles to enhance the antifungal efficacy of fluconazole against Candida albicans

BACKGROUND

Fluconazole (FLZ), a potent antifungal medication, is characterized by poor water solubility that reduced its antifungal efficacy.

OBJECTIVE

This study aimed to prepare FLZ-loaded polymeric nanoparticles (NPs) by using different polymers and techniques as a mean of enhancing the antifungal activity of FLZ.

METHODS

NP₁, NP₂, and NP₃ were prepared by the double emulsion/solvent evaporation method using PLGA, PCL, and PLA, respectively. The ionotropic pre-gelation technique was applied to prepare an alginate/chitosan-based formulation (NP₄). Particle size, zeta potential, encapsulation efficiency, and loading capacity were characterized. FT-IR spectra of FLZ, the polymers, and the prepared NPs were estimated. NP₄ was selected for further in-vitro release evaluation. The broth dilution method was used to assess the antifungal activity of NP₄ using a resistant clinical isolate of Candida albicans.

RESULTS

The double emulsion method produced smaller-sized particles (<390 nm) but with much lower encapsulation efficiency (< 12%). Alternatively, the ionic gelation method resulted in nanosized particles with a markedly higher encapsulation efficiency of about 40%. The FT-IR spectroscopy confirmed the loading of the FLZ molecules in the polymeric network of the prepared NPs. The release profile of NP₄ showed a burst initial release followed by a controlled pattern up to 24 hours with a higher percent released relative to the free FLZ suspension. NP₄ was able to reduce the value of MIC of FLZ by 20 times.

CONCLUSION

The antifungal activity of FLZ against C. albicans was enhanced markedly via its loading in the alginate/chitosan-based polymeric matrix of NP₄.

Nanoparticles as a Tool for Broadening Antifungal Activities

Fungal infections are diseases that are considered neglected although their infection rates have increased worldwide in the last decades. Thus, since the antifungal arsenal is restricted and many strains have shown resistance, new therapeutic alternatives are necessary. Nanoparticles are considered important alternatives to promote drug delivery. In this sense, the objective of the present study was to evaluate the contributions of newly developed nanoparticles to the treatment of fungal infections. Studies have shown that nanoparticles generally improve the biopharmaceutical and pharmacokinetic characteristics of antifungals, which is reflected in a greater pharmacodynamic potential and lower toxicity, as well as the possibility of prolonged action. It also offers the proposition of new routes of administration. Nanotechnology is known to contribute to a new drug delivery system, not only for the control of infectious diseases but for various other diseases as well. In recent years, several studies have emphasized its application in infectious diseases, presenting better alternatives for the treatment of fungal infections.

Phytol-Loaded Solid Lipid Nanoparticles as a Novel Anticandidal Nanobiotechnological Approach

Phytol is a diterpene alcohol and can be found as a product of the metabolism of chlorophyll in plants. This compound has been explored as a potential antimicrobial agent, but it is insoluble in water. In this study, we describe a novel approach for an interesting anticandidal drug delivery system containing phytol. Different formulations of phytol-loaded solid lipid nanoparticles (SLN) were designed and tested using a natural lipid, 1,3-distearyl-2-oleyl-glycerol (TG1). Different compositions were considered to obtain three formulations with 1:10, 1:5, and 1:3 w/w phytol/TG1 ratios. All the formulations were prepared by emulsification solvent evaporation method and had their physicochemical properties assessed. The biocompatibility assay was performed in the HEK-293 cell line and the antifungal efficacy was demonstrated in different strains of Candida ssp., including different clinical isolates. Spherical and uniform SLN (<300 nm, PdI < 0.2) with phytol-loading efficiency >65% were achieved. Phytol-loaded SLN showed a dose-dependent cytotoxic effect in the HEK-293 cell line. The three tested formulations of phytol-loaded SLN considerably enhanced the minimal inhibitory concentration of phytol against 15 strains of Candida spp. Considering the clinical isolates, the formulations containing the highest phytol/TG1 ratios showed MICs at 100%. Thus, the feasibility and potential of phytol-loaded SLN was demonstrated in vitro, being a promising nanocarrier for phytol delivery from an anticandidal approach.

Recent Advances in Polymeric Nanoparticle-Encapsulated Drugs against Intracellular Infections

Polymeric nanocarriers (PNs) have demonstrated to be a promising alternative to treat intracellular infections. They have outstanding performance in delivering antimicrobials intracellularly to reach an adequate dose level and improve their therapeutic efficacy. PNs offer opportunities for preventing unwanted drug interactions and degradation before reaching the target cell of tissue and thus decreasing the development of resistance in microorganisms. The use of PNs has the potential to reduce the dose and adverse side effects, providing better efficiency and effectiveness of therapeutic regimens, especially in drugs having high toxicity, low solubility in the physiological environment and low bioavailability. This review provides an overview of nanoparticles made of different polymeric precursors and the main methodologies to nanofabricate platforms of tuned physicochemical and morphological properties and surface chemistry for controlled release of antimicrobials in the target. It highlights the versatility of these nanosystems and their challenges and opportunities to deliver antimicrobial drugs to treat intracellular infections and mentions nanotoxicology aspects and future outlooks.

Potent and Specific Antibacterial Activity against Escherichia coli O157:H7 and Methicillin Resistant Staphylococcus aureus (MRSA) of G17 and G19 Peptides Encapsulated into Poly-Lactic-Co-Glycolic Acid (PLGA) Nanoparticles

Antimicrobial peptides constitute an excellent alternative against conventional antibiotics because of their potent antimicrobial spectrum, unspecific action mechanism and low capacity to produce antibiotic resistance. However, a potential use of these biological molecules as therapeutic agents is threatened by their low stability and susceptibility to proteases. In order to overcome these limitations, encapsulation in biocompatible polymers as poly-lactic-glycolic-acid (PLGA) is a promising alternative for increasing their stability and bioavailability. In this work, the effect of new synthetic antimicrobial peptides GIBIM-P5S9K (G17) and GAM019 (G19) encapsulated on PLGA and acting against methicillin resistant Staphylococus aureus (MRSA) and Escherichia coli O157:H7 was studied. PLGA encapsulation allowed us to load around 7 µg AMPs/mg PLGA with an efficiency of 90.5%, capsule sizes around 290 nm and positive charges. Encapsulation improved antimicrobial activity, decreasing MIC50 from 1.5 to 0.2 (G17NP) and 0.7 (G19NP) µM against MRSA, and from 12.5 to 3.13 µM for E. coli O157:H7. Peptide loaded nanoparticles could be a bacteriostatic drug with potential application to treat these bacterial E. coli O157:H7 and MRSA infections, with a slow and gradual release.

Fluconazole conjugated-gold nanorods as an antifungal nanomedicine with low cytotoxicity against human dermal fibroblasts

Herein, a nanotechnology-based approach was adopted to develop a facile and effective nanoplatform for the treatment of superficial fungal infections. Gold nanorods (GNR) functionalized with thiolated poly ethylene glycol (PEG-SH) or thiolated PEGylated cholesterol (Chol-PEG-SH) moieties were conjugated with Fluconazole and loaded into poloxamer 407 hydrogel. The obtained nanocomplexes; PEG-Fluc-GNR and Chol-Fluc-GNR were characterized by optical spectroscopy, hydrodynamic size and effective surface charge. The anti-fungal activity of the nanocomplexes was investigated by estimating the minimum inhibitory concentration (MIC) and the percentage reduction of fungal viable count against Candida (C.) albicans. PEG-Fluc-GNR and Chol-Fluc-GNR resulted in 5-fold and 14-fold reduction in MIC of GNR, and in 9-fold and 12-fold reduction in MIC of Fluconazole, respectively. The average log-reduction of the viable fungal cells upon treatment with the nanocomplexes was 5 log cycles, and it ranged from 1.3–3.7 log cycles when loaded into poloxamer 407 hydrogel. Transmission electron microscope imaging of the treated C. albicans revealed an enhanced uptake of the nanoparticles into the fungus's cell wall within the first 120 min of exposure. The nanocomplexes demonstrated low cytotoxicity towards human dermal fibroblasts which represent the human skin dermal cells. Conjugating Fluconazole with GNR is a promising approach for the effective treatment of superficial fungal infections.

A nanotechnology-based approach was adopted to develop a facile and effective nanoplatform for the treatment of superficial fungal infections.

In Vitro Antifungal and Antivirulence Activities of Biologically Synthesized Ethanolic Extract of Propolis-Loaded PLGA Nanoparticles against Candida albicans

Propolis is a natural substance and consists of bioactive compounds, which gives it antioxidant and antimicrobial properties. However, the use of propolis is limited by the low solubility in aqueous solutions. Thus, nanoparticles may be likely to accomplish enhanced delivery of poorly water-soluble phytomedicine. The aim of the present study was to fabricate and evaluate the biological activity of ethanolic extract of propolis-loaded poly(lactic-co-glycolic acid) nanoparticles (EEP-NPs). The EEP-NPs were prepared using the oil-in-water (o/w) single-emulsion solvent evaporation technique. The physicochemical properties of EEP-NPs were characterized and tested on their cytotoxicity, antifungal activity, and impact on key virulence factors that contribute to pathogenesis of C. albicans. EEP-NPs were successfully synthesized and demonstrated higher antifungal activity than EEP in free form. Moreover, EEP-NPs exhibited less cytotoxicity on Vero cells and suppressed the virulence factors of C. albicans, including adhesion, hyphal germination, biofilm formation, and invasion. Importantly, EEP-NPs exhibited a statistical decrease in the expression of hyphal adhesion-related genes, ALS3 and HWP1, of C. albicans. The results of this study revealed that EEP-NPs mediates a potent anticandidal activity and key virulence factors by reducing the gene-encoding virulence-associated hyphal- adhesion proteins of C. albicans and, thereby, disrupting the morphologic presence and attenuating their virulence.