Preparation, characterization and in vitro antiviral activity evaluation of foscarnet-chitosan nanoparticles

Latest advancements and trends in biomedical polymers for disease prevention, diagnosis, treatment, and clinical application

Biomedical polymers are at the forefront of medical advancements, offering innovative solutions in disease prevention, diagnosis, treatment, and clinical use due to their exceptional physicochemical properties. This review delves into the characteristics, classification, and preparation methods of these polymers, highlighting their diverse applications in drug delivery, medical imaging, tissue engineering, and regenerative medicine. We present a thorough analysis of the recent advancements in biomedical polymer research and their clinical applications, acknowledging the challenges that remain, such as immune response management, controlled degradation rates, and mechanical property optimization. Addressing these issues, we explore future directions, including personalization and the integration of nanotechnology, which hold significant potential for further advancing the field. This comprehensive review aims to provide a deep understanding of biomedical polymers and serve as a valuable resource for the development of innovative polymer materials in both fundamental research and clinical practice.

Formulation and Characterization of β-Cyclodextrins-Nitazoxanide Inclusion Complexes: Enhanced Solubility, In Vitro Drug Release, and Antiviral Activity in Vero Cells

Background/Objectives: Nitazoxanide (NTX) exhibits promising therapeutic potential; its effectiveness is constrained by its low oral bioavailability due to its poor water solubility and limited permeability. Methods: This study focused on developing a complex of NTX with β-cyclodextrins (β-CDs), specifically β-CD and hydroxypropyl-β-cyclodextrin (Hβ-CD), to enhance the solubility and antiviral activity of NTX. Results: The formation of the β-CD:NTX in an aqueous solution was verified using UV-visible spectroscopy, confirming a 1:1 inclusion complex. Characterization of the solid β-CD:NTX complexes was confirmed via FTIR, X-ray diffraction (XRD), scanning electron microscopy (SEM), and DSC-TGA analyses. Molecular docking studies revealed that the NTX thiazole ring with the nitro group was positioned within the β-CDs cavity, while the benzene ring remained outside. Phase solubility tests showed that β-CD:NTX complexes were formed with high stability constants, demonstrating a linear increase in NTX solubility as the β-CD concentration increased. Dissolution tests revealed rapid and nearly complete NTX release within 90 min for β-CD:NTX and Hβ-CD:NTX complexes. The β-CD:NTX complexes were tested for their antiviral activity against Herpes simplex virus (HSV-1) cultures. Results showed that the Hβ-CD:NTX complex had significantly higher antiviral efficacy than β-CD:NTX and free NTX alone. Moreover, cytotoxicity and cellular uptake studies on Vero cells indicated that the Hβ-CD:NTX complex demonstrated lower cytotoxicity and had the highest IC50 value, followed by β-CD:NTX and free NTX. Conclusions: These findings suggest that Hβ-CD:NTX inclusion complexes may serve as effective carriers for delivering NTX in HSV-1 treatments using Vero cell models.

Navigating Latency-Inducing Viral Infections: Therapeutic Targeting and Nanoparticle Utilization

The investigation into viral latency illuminates its pivotal role in the survival strategies of diverse viruses, including herpesviruses, HIV, and HPV. This underscores the delicate balance between dormancy and the potential for reactivation. The study explores the intricate mechanisms governing viral latency, encompassing episomal and proviral forms, and their integration with the host's genetic material. This integration provides resilience against cellular defenses, substantially impacting the host-pathogen dynamic, especially in the context of HIV, with implications for clinical outcomes. Addressing the challenge of eradicating latent reservoirs, this review underscores the potential of epigenetic and genetic interventions. It highlights the use of innovative nanocarriers like nanoparticles and liposomes for delivering latency-reversing agents. The precision in delivery, capacity to navigate biological barriers, and sustained drug release by these nanocarriers present a promising strategy to enhance therapeutic efficacy. The review further explores nanotechnology's integration in combating latent viral infections, leveraging nanoparticle-based platforms for drug delivery, gene editing, and vaccination. Advances in lipid-based nanocarriers, polymeric nanoparticles, and inorganic nanoparticles are discussed, illustrating their potential for targeted, efficient, and multifunctional antiviral therapy. By merging a deep understanding of viral latency's molecular underpinnings with nanotechnology's transformative capabilities, this review underscores the promise of novel therapeutic interventions. These interventions have great potential for managing persistent viral infections, heralding a new era in the fight against diseases such as neuroHIV/AIDS, herpes, and HPV.

Anti-Coronavirus Activity of Chitosan-Stabilized Liposomal Nanocarriers Loaded with Natural Extracts from Bulgarian Flora

Disease's severity, mortality rates, and common failures to achieve clinical improvement during the unprecedented COVID-19 pandemic exposed the emergency need for new antiviral therapeutics with higher efficacy and fewer adverse effects. This study explores the potential to encapsulate multi-component plant extracts in liposomes as optimized delivery systems and to verify if they exert inhibitory effects against human seasonal betacoronavirus OC43 (HCoV-OC43) in vitro. The selection of Sambucus nigra, Potentilla reptans, Allium sativum, Aesculus hippocastanum, and Glycyrrhiza glabra L. plant extracts was based on their established pharmacological and antiviral properties. The physicochemical characterization of extract-loaded liposomes was conducted by DLS and electrokinetics. Encapsulated amounts of the extract were evaluated based on the total flavonoid content (TFC) and total polyphenol content (TPC) by colorimetric methods. The BALB 3T3 neutral red uptake (NRU) phototoxicity/cytotoxicity assay was used to estimate compounds' safety. Photo irritation factors (PIFs) of the liposomes containing extracts were <2 which assigned them as non-phototoxic substances. The antiviral capacities of liposomes containing medicinal plant extracts against HCoV-OC43 were measured by the cytopathic effect inhibition test in susceptible HCT-8 cells. The antiviral activity increased by several times compared to "naked" extracts' activity reported previously. A. hippocastanum extract showed 16 times higher inhibitory properties reaching a selectivity index (SI) of 58.96. Virucidal and virus-adsorption effects were investigated using the endpoint dilution method and ∆lgs comparison with infected and untreated controls. The results confirmed that nanoparticles do not directly affect the viral surface or cell membrane, but only serve as carriers of the active substances and the observed protection is due solely to the intracellular action of the extracts.

Green synthesis of MnO2 NPs using Arabic gum: assessing its potential antiviral activity against influenza A/H1N1

BACKGROUND

The antiviral properties of metal nanoparticles against various viruses, including those resistant to drugs, are currently a subject of intensive research. Recently, the green synthesis of nanoparticles and their anti-viral function have attracted a lot of attention. Previous studies have shown promising results in the use of Arabic gum for the green synthesis of nanoparticles with strong antiviral properties. In this study we aimed to investigate the antiviral effects of MnO2 nanoparticles (MnO2-NPs) synthesized using Arabic gum, particularly against the influenza virus.

METHODS

Arabic gum was used as a natural polymer to extract and synthesize MnO2-NPs using a green chemistry approach. The synthesized MnO2-NPs were characterized using SEM and TEM. To evaluate virus titration, cytotoxicity, and antiviral activity, TCID50, MTT, and Hemagglutination assay (HA) were performed, respectively. Molecular docking studies were also performed to investigate the potential antiviral activity of the synthesized MnO2-NPs against the influenza virus. The molecular docking was carried out using AutoDock Vina software followed by an analysis with VMD software to investigate the interaction between Arabic gum and the hemagglutinin protein.

RESULTS

Simultaneous combination treatment with the green-synthesized MnO2-NPs resulted in a 3.5 log HA decrement and 69.7% cellular protection, which demonstrated the most significant difference in cellular protection compared to the virus control group (p-value < 0.01). The docking results showed that binding affinities were between - 3.3 and - 5.8 kcal/mole relating with the interaction between target with MnO2 and beta-D-galactopyranuronic acid, respectively.

CONCLUSION

The results of the study indicated that the MnO2-NPs synthesized with Arabic gum had significant antiviral effects against the influenza virus, highlighting their potential as a natural and effective treatment for inhibition of respiratory infections.

Polysaccharide-based nanoassemblies: From synthesis methodologies and industrial applications to future prospects

Polysaccharides, due to their remarkable features, have gained significant prominence in the sustainable production of nanoparticles (NPs). High market demand and minimal production cost, compared to the chemically synthesised NPs, demonstrate a drive towards polysaccharide-based nanoparticles (PSNPs) benign to environment. Various approaches are used for the synthesis of PSNPs including cross-linking, polyelectrolyte complexation, and self-assembly. PSNPs have the potential to replace a wide diversity of chemical-based agents within the food, health, medical and pharmacy sectors. Nevertheless, the considerable challenges associated with optimising the characteristics of PSNPs to meet specific targeting applications are of utmost importance. This review provides a detailed compilation of recent accomplishments in the synthesis of PSNPs, the fundamental principles and critical factors that govern their rational fabrication, as well as various characterisation techniques. Noteworthy, the multiple use of PSNPs in different disciplines such as biomedical, cosmetics agrochemicals, energy storage, water detoxification, and food-related realms, is accounted in detail. Insights into the toxicological impacts of the PSNPs and their possible risks to human health are addressed, and efforts made in terms of PSNPs development and optimising strategies that allow for enhanced delivery are highlighted. Finally, limitations, potential drawbacks, market diffusion, economic viability and future possibilities for PSNPs to achieve widespread commercial use are also discussed.

Human cytomegalovirus in cancer: the mechanism of HCMV-induced carcinogenesis and its therapeutic potential

Cancer is one of the leading causes of death worldwide. Human cytomegalovirus (HCMV), a well-studied herpesvirus, has been implicated in malignancies derived from breast, colorectal muscle, brain, and other cancers. Intricate host-virus interactions are responsible for the cascade of events that have the potential to result in the transformed phenotype of normal cells. The HCMV genome contains oncogenes that may initiate these types of cancers, and although the primary HCMV infection is usually asymptomatic, the virus remains in the body in a latent or persistent form. Viral reactivation causes severe health issues in immune-compromised individuals, including cancer patients, organ transplants, and AIDS patients. This review focuses on the immunologic mechanisms and molecular mechanisms of HCMV-induced carcinogenesis, methods of HCMV treatment, and other studies. Studies show that HCMV DNA and virus-specific antibodies are present in many types of cancers, implicating HCMV as an important player in cancer progression. Importantly, many clinical trials have been initiated to exploit HCMV as a therapeutic target for the treatment of cancer, particularly in immunotherapy strategies in the treatment of breast cancer and glioblastoma patients. Taken together, these findings support a link between HCMV infections and cellular growth that develops into cancer. More importantly, HCMV is the leading cause of birth defects in newborns, and infection with HCMV is responsible for abortions in pregnant women.

Anti-arthritic effects of geranium essential oil loaded chitosan nanoparticles in Freund's complete adjuvant induced arthritic rats through down-regulation of inflammatory cytokines

Geranium essential oil (GEO) has been widely used in aromatherapy and traditional medicines. Nanoencapsulation, a novel technique has emerged to overcome the environmental degradation and less oral bioavailability of essential oils. This work was undertaken to encapsulate geranium essential oil in chitosan nanoparticles (GEO-CNPs) by ionic gelation technique and to explore anti-arthritic and anti-inflammatory potential in FCA-induced arthritic model in rats. The GEO was characterized by gas chromatography flame ionization detector (GCFID) and the nanosuspension was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-rays diffraction (XRD). The Wistar albino rats (n = 32) were separated into four groups; Group 1 and 2 were considered as normal and arthritic controls. Group 3 was positive control that received oral celecoxib for 21 days while Group 4 was treated with oral GEO-CNPs after the induction of arthritis. Hind paw ankle joints diameters were weekly measured throughout the study and significant decrease (5.5 ± 0.5 mm) was observed in GEO-CNPs treatment group in comparison to arthritic group (9.17 ± 0.52 mm). Blood samples were drawn at end for evaluation of hematological, biochemical and inflammatory biomarkers. A significant upregulation of red blood cells and hemoglobin while downregulation of white blood cells, interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), C-reactive protein (CRP) and rheumatoid factor (RF) was observed. Ankles were transected for the histopathological and radiographic examination after animals were sacrificed which confirmed the alleviation of necrosis along cellular infiltration. It was concluded that GEO-CNPs were found to possess excellent therapeutic potential and promising candidates to reduce FCA-induced arthritis.

Anti-COVID-19 Credentials of Chitosan Composites and Derivatives: Future Scope?

Chitosan derivatives and composites are the next generation polymers for biomedical applications. With their humble origins from the second most abundant naturally available polymer chitin, chitosan is currently one of the most promising polymer systems, with wide biological applications. This current review gives a bird's eye view of the antimicrobial applications of chitosan composites and derivatives. The antiviral activity and the mechanisms behind the inhibitory activity of these components have been reviewed. Specifically, the anti-COVID-19 aspects of chitosan composites and their derivatives have been compiled from the existing scattered reports and presented. Defeating COVID-19 is the battle of this century, and the chitosan derivative-based combat strategies naturally become very attractive. The challenges ahead and future recommendations have been addressed.

Advances in Antiviral Delivery Systems and Chitosan-Based Polymeric and Nanoparticulate Antivirals and Antiviral Carriers

Current antiviral therapy research is focused on developing dosage forms that enable highly effective drug delivery, providing a selective effect in the organism, lower risk of adverse effects, a lower dose of active pharmaceutical ingredients, and minimal toxicity. In this article, antiviral drugs and the mechanisms of their action are summarized at the beginning as a prerequisite background to develop relevant drug delivery/carrier systems for them, classified and briefly discussed subsequently. Many of the recent studies aim at different types of synthetic, semisynthetic, and natural polymers serving as a favorable matrix for the antiviral drug carrier. Besides a wider view of different antiviral delivery systems, this review focuses on advances in antiviral drug delivery systems based on chitosan (CS) and derivatized CS carriers. CS and its derivatives are evaluated concerning methods of their preparation, their basic characteristics and properties, approaches to the incorporation of an antiviral drug in the CS polymer as well as CS nanoparticulate systems, and their recent biomedical applications in the context of actual antiviral therapy. The degree of development (i.e., research study, in vitro/ex vivo/in vivo preclinical testing), as well as benefits and limitations of CS polymer and CS nanoparticulate drug delivery systems, are reported for particular viral diseases and corresponding antivirotics.

Chitosan Nanoparticles as Oral Drug Carriers

The use of nanoparticles as drug delivery systems has increased in importance in the last decades. Despite the disadvantages of difficulty swallowing, gastric irritation, low solubility, and poor bioavailability, oral administration stands out as the most widely used route for therapeutic treatments, though it may not always be the most effective route. The effect of the first hepatic pass is one of the primary challenges that drugs must overcome to carry out their therapeutic effect. For these reasons, controlled-release systems based on nanoparticles synthesized from biodegradable natural polymers have been reported to be very efficient in enhancing oral delivery in multiple studies. Chitosan has been shown to have an extensive variability of properties and roles in the pharmaceutical and health fields; of its most important properties are the ability to encapsulate and transport drugs within the body and enhance the drug interaction with the target cells, which improves the efficacy of the encapsulated drugs. The physicochemical properties of chitosan give it the ability to form nanoparticles through multiple mechanisms, which will be addressed in this article. The present review article focuses on highlighting the applications of chitosan nanoparticles for oral drug delivery.

Antiviral role of nanomaterials: a material scientist's perspective

The present world continues to face unprecedented challenges caused by the COVID-19 pandemic. Collaboration between researchers of multiple disciplines is the need of the hour. There is a need to develop antiviral agents capable of inhibiting viruses and tailoring existing antiviral drugs for efficient delivery to prevent a surge in deaths caused by viruses globally. Biocompatible systems have been designed using nanotechnological principles which showed appreciable results against a wide range of viruses. Many nanoparticles can act as antiviral therapeutic agents if synthesized by the correct approach. Moreover, nanoparticles can act as carriers of antiviral drugs while overcoming their inherent drawbacks such as low solubility, poor bioavailability, uncontrolled release, and side effects. This review highlights the potential of nanomaterials in antiviral applications by discussing various studies and their results regarding antiviral potential of nanoparticles while also suggesting future directions to researchers.

Chitosan and its derivatives as polymeric anti-viral therapeutics and potential anti-SARS-CoV-2 nanomedicine

The coronavirus pandemic, COVID-19 has a global impact on the lives and livelihoods of people. It is characterized by a widespread infection by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), where infected patients may develop serious medical complications or even face death. Development of therapeutic is essential to reduce the morbidity and mortality of infected patients. Chitosan is a versatile biomaterial in nanomedicine and exhibits anti-microbial, anti-cancer and immunomodulatory properties. This review highlights the progress in chitosan design and application pertaining to the anti-viral effects of chitosan and chitosan derivatives (hydroxypropyl trimethylammonium, sulfate, carboxymethyl, bromine, sialylglycopolymer, peptide and phosphonium conjugates) as a function of molecular weight, degree of deacetylation, type of substituents and their degree and site of substitution. The physicochemical attributes of these polymeric therapeutics are identified against the possibility of processing them into nanomedicine which can confer a higher level of anti-viral efficacy. The designs of chitosan for the purpose of targeting SARS-CoV-2, as well as the ever-evolving strains of viruses with a broad spectrum anti-viral activity to meet pandemic preparedness at the early stages of outbreak are discussed.

Relationship between the Antifungal Activity of Chitosan-Capsaicin Nanoparticles and the Oxidative Stress Response on Aspergillus parasiticus

The fungus Aspergillus parasiticus is a contaminant in agricultural crops and its eradication involves the indiscriminate use of harmful synthetic pesticides. In the search for antifungal agents of natural origin, chitosan (Q) and capsaicin (C) are coupled in the form of nanoparticles (Np), which can possess a direct application under specific conditions. Due to their small size, Np can cross through the cell wall, taking the cells into a pro-oxidant environment known as “oxidative stress”, which presents when the reactive oxygen species (ROS) surpass the number of antioxidants in the cell. In the present investigation, nanoparticles of chitosan (Np Q) and nanoparticles of chitosan-capsaicin (Np QC) with an average diameter of 44.8 ± 20.6 nm and 111.1 ± 14.1 nm, respectively, were synthesized, and there was a zeta potential of + 25.6 ± 0.7 mV and + 26.8 ± 6.1 mV, respectively. The effect of the concentration of Np Q (A, B, C, and D), of Np QC (A, B, C, and D), and capsaicin in a solution (control) was evaluated on the viability of the spores, the accumulation of intracellular ROS, and the morphometric changes of A. parasiticus. Acute toxicity of the Np was determined utilizing bioassays with Artemia salina, and acute phytotoxicity was evaluated in lettuce seeds (Lactuca sativa). According to ROS results, capsaicin (control) did not induce oxidative stress in the cell; otherwise, it was observed to have an elevated (p < 0.05) accumulation of ROS when the concentration of Np Q increased. For both, Np Q and Np QC, an inverse physiological pattern relating spore viability and ROS accumulation in the fungus was found; the viability of spores decreased as the ROS accumulation increased. The spore viability of A. parasiticus diminished upon increasing the concentration of chitosan (0.3−0.4 mg/mL) in the Np, while the intracellular accumulation of ROS increased proportionally to the concentration of the nanomaterials in the treatments of Np Q and Np QC. On the other hand, Np QC presented a lower (p < 0.05) toxicological effect in comparison with Np Q, which indicates that the incorporation of bioactive compounds, such as capsaicin, into nanoparticles of chitosan is a strategy that permits the reduction of the toxicity associated with nanostructured materials.

Towards the Antiviral Agents and Nanotechnology-Enabled Approaches Against Parvovirus B19

Parvovirus B19 (B19V) as a human pathogenic virus, would cause a wide range of clinical manifestations. Besides the supportive and symptomatic treatments, the only FDA-approved antiviral drug for the treatment of B19V is intravenous immunoglobulins, which however, have limited efficacy and high cost. By far, there are still no virus-specific therapeutics clinically available to treat B19V infection. Therefore, exploiting the potential targets with a deep understanding of the life cycle of B19V, are pivotal to the development of B19V-tailored effective antiviral approaches. This review will introduce antiviral agents via blocking viral invasion, inhibiting the enzymes or regulatory proteins involved in DNA synthesis, and so on. Moreover, nanotechnology-enabled approaches against B19V will also be outlined and discussed through a multidisciplinary perspective involving virology, nanotechnology, medicine, pharmaceutics, chemistry, materials science, and other fields. Lastly, the prospects of the antiviral agents and nanosystems in terms of fabrication, clinical translation and potential breakthroughs will be briefly discussed.

Chitosan Nanoparticles in Atherosclerosis-Development to Preclinical Testing

Chitosan is a natural biopolymer that is present in an abundant supply in sources such as crustacean shells, mushrooms, and insect exoskeletons. It can be used to make a variety of types of drug formulations and is generally safe to use in vivo; plus, it has inherent cholesterol-reducing properties. While an abundance of papers has tested this biopolymer in nanoparticles in cancer and diabetes research, there is a lag of usage, and hence the paucity of information, in the area of cardiovascular research, specifically in atherosclerosis, the topic of this review. This review highlights some of the deficiencies in this niche area of research, examines the range of chitosan nanoparticles that have been researched to date, and proposes several ways forward to advance this field. Nanoparticles used for both diagnostic and therapeutic purposes are reviewed, with a discussion on how these nanoparticles could be better researched in future and what lays ahead as the field potentially moves towards clinical trials in future.

Antiviral Polymers: A Review

Polymers, due to their high molecular weight, tunable architecture, functionality, and buffering effect for endosomal escape, possess unique properties as a carrier or prophylactic agent in preventing pandemic outbreak of new viruses. Polymers are used as a carrier to reduce the minimum required dose, bioavailability, and therapeutic effectiveness of antiviral agents. Polymers are also used as multifunctional nanomaterials to, directly or indirectly, inhibit viral infections. Multifunctional polymers can interact directly with envelope glycoproteins on the viral surface to block fusion and entry of the virus in the host cell. Polymers can indirectly mobilize the immune system by activating macrophages and natural killer cells against the invading virus. This review covers natural and synthetic polymers that possess antiviral activity, their mechanism of action, and the effect of material properties like chemical composition, molecular weight, functional groups, and charge density on antiviral activity. Natural polymers like carrageenan, chitosan, fucoidan, and phosphorothioate oligonucleotides, and synthetic polymers like dendrimers and sialylated polymers are reviewed. This review discusses the steps in the viral replication cycle from binding to cell surface receptors to viral-cell fusion, replication, assembly, and release of the virus from the host cell that antiviral polymers interfere with to block viral infections.

Foscarnet-Type Inorganic-Organic Hybrid Nanoparticles for Effective Antiviral Therapy

[ZrO]²⁺[(FCN)_0.4(OH)_0.8]^2- and Gd³⁺[FCN]^3- inorganic-organic hybrid nanoparticles (IOH-NPs) are novel saline antiviral nanocarriers with foscarnet (FCN) as a drug anion. FCN as a pyrophosphate analogue serves as a prototype of a viral DNA polymerase inhibitor. FCN is used for the treatment of herpesvirus infections, including the drug-resistant cytomegalovirus (CMV) and herpes simplex viruses, HSV-1 and HSV-2. The novel [ZrO]²⁺[(FCN)_0.4(OH)_0.8]^2- and Gd³⁺[FCN]^3- IOH-NPs are characterized by aqueous synthesis, small size (20-30 nm), low material complexity, high biocompatibility, and high drug load (up to 44 wt % FCN per nanoparticle). The antiviral activity of the FCN-type IOH-NPs is probed for the human cytomegalovirus (HCMV). Moreover, the uptake of FCN-type IOH-NPs into vesicles, cytoplasm, and nuclei of nonphagocytic lung epithelial cells is evaluated. As a result, a promising antiviral activity of the FCN-type IOH-NPs that significantly outperforms freely dissolved FCN at the level of clinical formulations is observed, encouraging a future use of FCN-type IOH-NPs for the delivery of antivirals against respiratory viruses.

A review of the antiviral activity of Chitosan, including patented applications and its potential use against COVID-19

Chitosan is an abundant organic polysaccharide, which can be relatively easily obtained by chemical modification of animal or fungal source materials. Chitosan and its derivatives have been shown to exhibit direct antiviral activity, to be useful vaccine adjuvants and to have potential anti-SARS-CoV-2 activity. This thorough and timely review looks at the recent history of investigations into the role of chitosan and its derivatives as an antiviral agent and proposes a future application in the treatment of endemic SARS-CoV-2.

Potential of mucoadhesive chitosan glutamate microparticles as microbicide carriers - antiherpes activity and penetration behavior across the human vaginal epithelium

Chitosan glutamate (gCS) spray-dried microparticles appear promising carriers to overcome challenges associated with vaginal microbicide delivery. This study aimed at elucidating the penetration and mucoadhesive behavior of developed gCS multiunit carriers with zidovudine (ZVD) as a model antiretroviral agent in contact with excised human vaginal epithelium followed with an examination of in vitro antiherpes activity in immortal human keratinocytes HaCaT and human vaginal epithelial cells VK2-E6/E7. Both ZVD dispersion and placebo microparticles served as controls. Microparticles displayed feasible (comparable to commercial vaginal product) mucoadhesive and mucoretention characteristics to isolated human vaginal tissue. Ex vivo penetration studies revealed that gCS increased the accumulation of active agent in the vaginal epithelium but surprisingly did not facilitate its penetration across human tissue. Finally, the obtained antiviral results demonstrated the potential of gCS as an antiherpes adjunctive, whose mode of action was related to blocking viral attachment.

Preparation and Antimicrobial Activity of Chitosan and Its Derivatives: A Concise Review

Despite the advantages presented by synthetic polymers such as strength and durability, the lack of biodegradability associated with the persistence in the environment for a long time turned the attention of researchers to natural polymers. Being biodegradable, biopolymers proved to be extremely beneficial to the environment. At present, they represent an important class of materials with applications in all economic sectors, but also in medicine. They find applications as absorbers, cosmetics, controlled drug delivery, tissue engineering, etc. Chitosan is one of the natural polymers which raised a strong interest for researchers due to some exceptional properties such as biodegradability, biocompatibility, nontoxicity, non-antigenicity, low-cost and numerous pharmacological properties as antimicrobial, antitumor, antioxidant, antidiabetic, immunoenhancing. In addition to this, the free amino and hydroxyl groups make it susceptible to a series of structural modulations, obtaining some derivatives with different biomedical applications. This review approaches the physico-chemical and pharmacological properties of chitosan and its derivatives, focusing on the antimicrobial potential including mechanism of action, factors that influence the antimicrobial activity and the activity against resistant strains, topics of great interest in the context of the concern raised by the available therapeutic options for infections, especially with resistant strains.

Development of nanoparticle-delivery systems for antiviral agents: A review

The COVID-19 pandemic has resulted in unprecedented increases in sickness, death, economic disruption, and social disturbances globally. However, the virus (SARS-CoV-2) that caused this pandemic is only one of many viruses threatening public health. Consequently, it is important to have effective means of preventing viral transmission and reducing its devastating effects on human and animal health. Although many antivirals are already available, their efficacy is often limited because of factors such as poor solubility, low permeability, poor bioavailability, un-targeted release, adverse side effects, and antiviral resistance. Many of these problems can be overcome using advanced antiviral delivery systems constructed using nanotechnology principles. These delivery systems consist of antivirals loaded into nanoparticles, which may be fabricated from either synthetic or natural materials. Nevertheless, there is increasing emphasis on the development of antiviral delivery systems from natural substances, such as lipids, phospholipids, surfactants, proteins, and polysaccharides, due to health and environmental issues. The composition, morphology, dimensions, and interfacial characteristics of nanoparticles can be manipulated to improve the handling, stability, and potency of antivirals. This article outlines the major classes of antivirals, summarizes the challenges currently limiting their efficacy, and highlights how nanoparticles can be used to overcome these challenges. Recent studies on the application of antiviral nanoparticle-based delivery systems are reviewed and future directions are described.

An overview of functional nanoparticles as novel emerging antiviral therapeutic agents

Research on highly effective antiviral drugs is essential for preventing the spread of infections and reducing losses. Recently, many functional nanoparticles have been shown to possess remarkable antiviral ability, such as quantum dots, gold and silver nanoparticles, nanoclusters, carbon dots, graphene oxide, silicon materials, polymers and dendrimers. Despite their difference in antiviral mechanism and inhibition efficacy, these functional nanoparticles-based structures have unique features as potential antiviral candidates. In this topical review, we highlight the antiviral efficacy and mechanism of these nanoparticles. Specifically, we introduce various methods for analyzing the viricidal activity of functional nanoparticles and the latest advances in antiviral functional nanoparticles. Furthermore, we systematically describe the advantages and disadvantages of these functional nanoparticles in viricidal applications. Finally, we discuss the challenges and prospects of antiviral nanostructures. This topic review covers 132 papers and will enrich our knowledge about the antiviral efficacy and mechanism of various functional nanoparticles.

The Correlation between Physical Crosslinking and Water-Soluble Drug Release from Chitosan-Based Microparticles

Microparticles containing water-soluble zidovudine were prepared by spray-drying using chitosan glutamate and beta-glycerophosphate as an ion crosslinker (CF). The Box–Behnken design was applied to optimize the microparticles in terms of their drug loading and release behavior. Physicochemical studies were undertaken to support the results from dissolution tests and to evaluate the impact of the crosslinking ratio on the microparticles’ characteristics. The zidovudine dissolution behavior had a complex nature which comprised two phases: an initial burst effect followed with a prolonged release stage. The initial drug release, which can be modulated by the crosslinking degree, was primarily governed by the dissolution of the drug crystals located on the microparticles’ surfaces. In turn, the further dissolution stage was related to the drug diffusion from the swollen polymer matrix and was found to correlate with the drug loading. Differential Scanning Calorimetry (DSC) studies revealed the partial incorporation of a non-crystallized drug within the polymer matrix, which correlated with the amount of CF. Although CF influenced the swelling capacity of chitosan glutamate microparticles, surprisingly a higher amount of CF did not impact the time required for 80% of the drug to be released markedly. The formulation with the lowest polymer:CF ratio, 3:1, was selected as optimal, providing satisfactory drug loading and displaying a moderate burst effect within the first 30 min of the study, followed with a prolonged drug release of up to 210 min.

Improving the antifungal activity of clove essential oil encapsulated by chitosan nanoparticles

Encapsulation of clove essential oil (CEO) by chitosan nanoparticles (ChNPs) was performed, using an emulsion-ionic gelation technique to improve the antifungal efficacy of CEO. The mass ratios of chitosan (Ch) to tripolyphosphate (TPP), 1:1, for unloaded ChNPs and 1:1:1 for Ch to TPP to CEO, for CEO-loaded ChNPs (CEO-ChNPs), were selected as optimum formulations based on dynamic light scattering and ultraviolet-visible spectroscopy. The presence of CEO in optimum CEO-ChNPs, was evidenced by Fourier transform infrared spectroscopy. Particle size distribution, of around 40 and 100 nm for the most optimum unloaded and oil-loaded ChNPs, was obtained by field emission-scanning electron microscopy. In vitro release studies of CEO-ChNPs revealed a controlled release during 56 days. The nano-encapsulated CEO demonstrated a superior performance against Aspergillus niger, isolated from spoiled pomegranate, compared with ChNPs and free oil. Therefore, this study revealed that CEO-ChNPs can be used as a promising natural fungicide in agriculture and food industry.

Scaffolds as Structural Tools for Bone-Targeted Drug Delivery

Although bone has a high potential to regenerate itself after damage and injury, the efficacious repair of large bone defects resulting from resection, trauma or non-union fractures still requires the implantation of bone grafts. Materials science, in conjunction with biotechnology, can satisfy these needs by developing artificial bones, synthetic substitutes and organ implants. In particular, recent advances in materials science have provided several innovations, underlying the increasing importance of biomaterials in this field. To address the increasing need for improved bone substitutes, tissue engineering seeks to create synthetic, three-dimensional scaffolds made from organic or inorganic materials, incorporating drugs and growth factors, to induce new bone tissue formation. This review emphasizes recent progress in materials science that allows reliable scaffolds to be synthesized for targeted drug delivery in bone regeneration, also with respect to past directions no longer considered promising. A general overview concerning modeling approaches suitable for the discussed systems is also provided.

Advanced Prodrug Strategies in Nucleoside and Non-Nucleoside Antiviral Agents: A Review of the Recent Five Years

Background: Poor pharmacokinetic profiles and resistance are the main two drawbacks from which currently used antiviral agents suffer, thus make them excellent targets for research, especially in the presence of viral pandemics such as HIV and hepatitis C. Methods: The strategies employed in the studies covered in this review were sorted by the type of drug synthesized into ester prodrugs, targeted delivery prodrugs, macromolecular prodrugs, other nucleoside conjugates, and non-nucleoside drugs. Results: Utilizing the ester prodrug approach a novel isopropyl ester prodrug was found to be potent HIV integrase inhibitor. Further, employing the targeted delivery prodrug zanamivir and valine ester prodrug was made and shown a sole delivery of zanamivir. Additionally, VivaGel, a dendrimer macromolecular prodrug, was found to be very efficient and is now undergoing clinical trials. Conclusions: Of all the strategies employed (ester, targeted delivery, macromolecular, protides and nucleoside analogues, and non-nucleoside analogues prodrugs), the most promising are nucleoside analogues and macromolecular prodrugs. The macromolecular prodrug VivaGel works by two mechanisms: envelope mediated and receptor mediated disruption. Nucleotide analogues have witnessed productive era in the recent past few years. The era of non-interferon based treatment of hepatitis (through direct inhibitors of NS5A) has dawned.

Electrostatic Self-Assembled Chitosan-Pectin Nano- and Microparticles for Insulin Delivery

A polyelectrolyte complex system of chitosan-pectin nano- and microparticles was developed to encapsulate the hormone insulin. The aim of this work was to obtain small particles for oral insulin delivery without chemical crosslinkers based on natural and biodegradable polysaccharides. The nano- and microparticles were developed using chitosans (with different degrees of acetylation: 15.0% and 28.8%) and pectin solutions at various charge ratios (n⁺/n^- given by the chitosan/pectin mass ratio) and total charge. Nano- and microparticles were characterized regarding particle size, zeta potential, production yield, encapsulation efficiency, stability in different media, transmission electron microscopy and cytotoxicity assays using Caco-2 cells. The insulin release was evaluated in vitro in simulated gastric and intestinal media. Small-sized particles (~240-~1900 nm) with a maximum production yield of ~34.0% were obtained. The highest encapsulation efficiency (~62.0%) of the system was observed at a charge ratio (n⁺/n^-) 5.00. The system was stable in various media, particularly in simulated gastric fluid (pH 1.2). Transmission electron microscopy (TEM) analysis showed spherical shape particles when insulin was added to the system. In simulated intestinal fluid (pH 6.8), controlled insulin release occurred over 2 h. In vitro tests indicated that the proposed system presents potential as a drug delivery for oral administration of bioactive peptides.

Chitosan-clodronate nanoparticles loaded in poloxamer gel for intra-articular administration

This work was based on the study of an intra-articular delivery system constituted by a poloxamer gel vehiculating clodronate in chitosan nanoparticles. This system has been conceived to obtain a specific and controlled release of clodronate in the joints to reduce the arthritis rheumatoid degenerative effect. Clodronate (CLO) is a first-generation bisphosphonate with anti-inflammatory properties, inhibiting the cytokine and NO secretion from macrophages, therefore causing apoptosis in these cells. This is related to its ability to be metabolized by cells and converted into a cytotoxic intermediate as a non-hydrolysable analogue of ATP. Chitosan (CHI) was used to develop nanosystems, by ionotropic gelation induced by clodronate itself. A fractional factorial experimental design allowed us to obtain nanoparticles, the diameter of which ranged from 200 to 300nm. Glutaraldehyde was used to increase nanoparticle stability and modify the drug release profile. The zeta potential value of crosslinked nanopaparticles was 21.0mV±1.3, while drug loading was 31.0%±5.4 w/w; nanoparticle yield was 18.2%±1.8 w/w, the encapsulation efficiency was 48.8%±9.9 w/w. Nanoparticles were homogenously loaded in a poloxamer sol, and the drug delivery system is produced in-situ after local administration, when sol become gel at physiological temperature. The properties of poloxamer gels containing CHI-CLO nanoparticles, such as viscosity, gelation temperature and drug release properties, were evaluated. In vitro studies were conducted to evaluate the effects of these nanoparticles on a human monocytic cell line (THP1). The results showed that this drug delivery system is more efficient, with respect to the free drug, to counteract the inflammatory process characteristic of several degenerative diseases.