Formulation of a Composite Nasal Spray Enabling Enhanced Surface Coverage and Prophylaxis of SARS-COV-2

Toward a Radically Simple Multi-Modal Nasal Spray for Preventing Respiratory Infections

Nasal sprays for pre-exposure prophylaxis against respiratory infections show limited protection (20-70%), largely due to their single mechanism of action-either neutralizing pathogens or blocking their entry at the nasal lining, and a failure to maximize the capture of respiratory droplets, allowing them to potentially rebound and reach deeper airways. This report introduces the Pathogen Capture and Neutralizing Spray (PCANS), which utilizes a multi-modal approach to enhance efficacy. PCANS coats the nasal cavity, capturing large respiratory droplets from the air, and serving as a physical barrier against a broad spectrum of viruses and bacteria, while rapidly neutralizing them with over 99.99% effectiveness. The formulation consists of excipients identified from the FDA's Inactive Ingredient Database and Generally Recognized as Safe list to maximize efficacy for each step in the multi-modal approach. PCANS demonstrates nasal retention for up to 8 hours in mice. In a severe Influenza A mouse model, a single pre-exposure dose of PCANS leads to a >99.99% reduction in lung viral titer and ensures 100% survival, compared to 0% in the control group. PCANS suppresses pathological manifestations and offers protection for at least 4 hours. This data suggest PCANS as a promising daily-use prophylactic against respiratory infections.

An Inhalable Nanoshield for Effective Prevention of Influenza Virus Infections

Influenza virus (IV) infection currently poses a serious and continuing threat to the global public health. Developing effective prevention strategies is important to defend against infection and spread of IV. Here, we developed a triple-protective nanoshield against IV infection in the lungs, formed by self-assembling DSPE-PEG amphiphilic polymers encapsulating the flu-preventive antiviral drug Arbidol internally. The preventive effect of the nanoshield against virus infection includes increasing the viscosity in the surrounding environment to physically defend against viral entry, forming a hydrated layer to block the interaction between viruses and cells, and inhibiting virus replication. Our finding suggested that a single inhalation of the nanoshield provides effective protection against IV infection for at least 8 h. Thus, this nanoshield may be a potential pandemic protection agent against IV, especially in viral environments, where no prophylactic or therapeutic measures are available.

Sprayable anti-adhesive hydrogel for peritoneal macrophage scavenging in post-surgical applications

Post-surgical adhesions frequently occur after intra-abdominal surgery, leading to severe complications. Despite the development of various types of adhesion barriers to address post-surgical adhesions, several limitations persist, including off-target localization, handling difficulties, and potential immunogenicity. Here, we report a spray-type adhesion barrier for broad, fast application, forming two sequential networks. The first network is formed by a polyelectrolyte complex of sulfated hyaluronic acid and chitosan, while the second network is established through pluronic® F127 thermogelation. This sprayable barrier served as both a physical protector for the damaged peritoneum and an immunomodulator for peritoneal macrophages, as evidenced its effectiveness in a rat ischemic button model. Taken together, this efficient adhesion barrier presents a promising solution for post-surgical adhesions.

Structurally defined heparin octasaccharide domain for binding to SARS-CoV-2 Omicron BA.4/BA.5/BA.5.2 spike protein RBD

Heparin, a bio-molecule with the highest negative charge density, is pharmaceutically important to prevent SARS-CoV-2 infection due to its strong competitive binding to spike protein compared with cellular heparan sulfate, which was confirmed as a co-receptor for virus-host cell interaction. Hence, the refined structural characterization of heparin targeting viral protein-HS interaction was significant for developing antiviral pharmaceuticals. In our study, heparin oligomers (dp ≥ 4) were prepared using heparinase I. The affinity oligosaccharides binding to Omicron spike protein RBD were separated by affinity chromatography and size exclusion chromatography. HILIC-ESI-FTMS was used for chain mapping analysis. The basic building blocks were analyzed and the binding domain sequence was produced by Seq-GAG software and further measured by SAX chromatography. As results, heparin octasaccharide was found with significantly higher binding ability than hexasaccharide and tetrasaccharide, and the octasaccharide [ΔUA-GlcNS6S-GlcA-GlcNS6S-IdoA2S-GlcNS6S-IdoA2S-GlcNS6S] with 12 sulfate groups showed high binding to RBD. The mechanism of this structurally well-defined octasaccharide binding to RBD was further investigated by molecular docking. The affinity energy of optimal pose was -6.8 kcal/mol and the basic amino acid residues in RBD sequence (Arg403, Arg452, Arg493 and His505) were identified as the major contribution factor to interacting with sulfate/carboxyl groups on saccharide chain. Our study demonstrated that heparin oligosaccharide with well-defined structure could be potentially developed as anti-SARS-CoV-2 drugs.

Intranasal mask for protecting the respiratory tract against viral aerosols

The spread of many infectious diseases relies on aerosol transmission to the respiratory tract. Here we design an intranasal mask comprising a positively-charged thermosensitive hydrogel and cell-derived micro-sized vesicles with a specific viral receptor. We show that the positively charged hydrogel intercepts negatively charged viral aerosols, while the viral receptor on vesicles mediates the entrapment of viruses for inactivation. We demonstrate that when displaying matched viral receptors, the intranasal masks protect the nasal cavity and lung of mice from either severe acute respiratory syndrome coronavirus 2 or influenza A virus. With computerized tomography images of human nasal cavity, we further conduct computational fluid dynamics simulation and three-dimensional printing of an anatomically accurate human nasal cavity, which is connected to human lung organoids to generate a human respiratory tract model. Both simulative and experimental results support the suitability of intranasal masks in humans, as the likelihood of viral respiratory infections induced by different variant strains is dramatically reduced.

Degradable carrier-free spray hydrogel based on self-assembly of natural small molecule for prevention of postoperative adhesion

Postoperative peritoneal adhesion (PPA) is frequent and extremely dangerous complication after surgery. Different tactics have been developed to reduce it. However, creating a postoperative adhesion method that is multifunctional, biodegradable, biocompatible, low-toxic but highly effective, and therapeutically applicable is still a challenge. Herein, we have prepared a degradable spray glycyrrhetinic acid hydrogel (GAG) based on natural glycyrrhetinic acid (GA) by straightforward heating and cooling without the use of any additional chemical cross-linking agents to prevent postoperative adhesion. The resultant hydrogel was demonstrated to possess various superior anti-inflammatory activity, and multiple functions, such as excellent degradability and biocompatibility. Specifically, spraying characteristic and excellent antibacterial activities essentially eliminated secondary infections during the administration of drugs in surgical wounds. In the rat models, the carrier-free spray GAG could not only slow-release GA to inhibit inflammatory response, but also serve as physical anti-adhesion barrier to reduce collagen deposition and fibrosis. The sprayed GAG would shed a new light on the prevention of postoperative adhesion and broaden the application of the hydrogels based on natural products in biomedical fields.

Nasal delivery as a strategy for the prevention and treatment of COVID-19

INTRODUCTION

The upper respiratory tract is a major route of infection for COVID-19 and other respiratory diseases. Thus, it appears logical to exploit the nose as administration site to prevent, fight, or minimize infectious spread and treat the disease. Numerous nasal products addressing these aspects have been considered and developed for COVID-19.

AREAS COVERED

This review gives a comprehensive overview of the different approaches involving nasal delivery, i.e., nasal vaccination, barrier products, and antiviral pharmacological treatments that have led to products on the market or under clinical evaluation, highlighting the peculiarities of the nose as application and absorption site and pointing at key aspects of nasal drug delivery.

EXPERT OPINION

From the analysis of nasal delivery strategies to prevent or fight COVID-19, it emerges that, especially for nasal immunization, formulations appear the same as originally designed for parenteral administration, leading to suboptimal results. On the other hand, mechanical barrier and antiviral products, designed to halt or treat the infection at early stage, have been proven effective but were rarely brought to the clinics. If supported by robust and targeted product development strategies, intranasal immunization and drug delivery can represent valid and sometimes superior alternatives to more conventional parenteral and oral medications.

Aqueous cannabidiol β-cyclodextrin complexed polymeric micelle nasal spray to attenuate in vitro and ex-vivo SARS-CoV-2-induced cytokine storms

Cannabidiol (CBD) has a number of biological effects by acting on the cannabinoid receptors CB₁ and CB₂. CBD may be involved in anti-inflammatory processes via CB₁ and CB₂ receptors, resulting in a decrease of pro-inflammatory cytokines. However, CBD's poor aqueous solubility is a major issue in pharmaceutical applications. The aim of the present study was to develop and evaluate a CBD nasal spray solution. A water-soluble CBD was prepared by complexation with β-cyclodextrin (β-CD) at a stoichiometric ratio of 1:1 and forming polymeric micelles using poloxamer 407. The mixture was then lyophilized and characterized using FT-IR, DSC, and TGA. CBD-β-CD complex-polymeric micelles were formulated for nasal spray drug delivery. The physicochemical properties of the CBD-β-CD complex-polymeric micelle nasal spray solution (CBD-β-CDPM-NS) were assessed. The results showed that the CBD content in the CBD-β-CD complex polymeric micelle powder was 102.1 ± 0.5%. The CBD-β-CDPM-NS was a clear colorless isotonic solution. The particle size, zeta potential, pH value, and viscosity were 111.9 ± 0.7 nm, 0.8 ± 0.1 mV, 6.02 ± 0.02, and 12.04 ± 2.64 cP, respectively. This formulation was stable over six months at ambient temperature. The CBD from CBD-β-CDPM-NS rapidly released to 100% within 1 min. Ex-vivo permeation studies of CBD-β-CDPM-NS through porcine nasal mucosa revealed a permeation rate of 4.8 μg/cm²/min, which indicated that CBD was effective in penetrating nasal epithelial cells. CBD-β-CDPM-NS was tested for its efficacy and safety in terms of cytokine production from nasal immune cells and toxicity to nasal epithelial cells. The CBD-β-CDPM-NS was not toxic to nasal epithelial at the concentration of CBD equivalent to 3.125-50 μg/mL. When the formulation was subjected to bioactivity testing against monocyte-like macrophage cells, it proved that the CBD-β-CDPM-NS has the potential to inhibit inflammatory cytokines. CBD-β-CDPM-NS demonstrated the formulation's ability to reduce the cytokine produced by S-RBD stimulation in ex vivo porcine nasal mucosa in both preventative and therapeutic modes.

Porous Cellulose Thin Films as Sustainable and Effective Antimicrobial Surface Coatings

In the present work, we developed an effective antimicrobial surface film based on sustainable microfibrillated cellulose. The resulting porous cellulose thin film is barely noticeable to human eyes due to its submicrometer thickness, of which the surface coverage, porosity, and microstructure can be modulated by the formulations and the coating process. Using goniometers and a quartz crystal microbalance, we observed a threefold reduction in water contact angles and accelerated water evaporation kinetics on the cellulose film (more than 50% faster than that on a flat glass surface). The porous cellulose film exhibits a rapid inactivation effect against SARS-CoV-2 in 5 min, following deposition of virus-loaded droplets, and an exceptional ability to reduce contact transfer of liquid, e.g., respiratory droplets, to surfaces such as an artificial skin by 90% less than that from a planar glass substrate. It also shows excellent antimicrobial performance in inhibiting the growth of both Gram-negative and Gram-positive bacteria (Escherichia coli and Staphylococcus epidermidis) due to the intrinsic porosity and hydrophilicity. Additionally, the cellulose film shows nearly 100% resistance to scraping in dry conditions due to its strong affinity to the supporting substrate but with good removability once wetted with water, suggesting its practical suitability for daily use. Importantly, the coating can be formed on solid substrates readily by spraying, which requires solely a simple formulation of a plant-based cellulose material with no chemical additives, rendering it a scalable, affordable, and green solution as antimicrobial surface coating. Implementing such cellulose films could thus play a significant role in controlling future pan- and epidemics, particularly during the initial phase when suitable medical intervention needs to be developed and deployed.

Recent advances in exploiting carrageenans as a versatile functional material for promising biomedical applications

Carrageenans are a group of biopolymers widely found in red seaweeds. Commercial carrageenans have been traditionally used as emulsifiers, stabilizers, and thickening and gelling agents in food products. Carrageenans are regarded as bioactive polysaccharides with disease-modifying and microbiota-modulating activities. Novel biomedical applications of carrageenans as biocompatible functional materials for fabricating hydrogels and nanostructures, including carbon dots, nanoparticles, and nanofibers, have been increasingly exploited. In this review, we describe the unique structural characteristics of carrageenans and their functional relevance. We summarize salient physicochemical features, including thixotropic and shear-thinning properties, of carrageenans. Recent results from clinical trials in which carrageenans were applied as both antiviral and antitumor agents and functional materials are discussed. We also highlight the most recent advances in the development of carrageenan-based targeted drug delivery systems with various pharmaceutical formulations. Promising applications of carrageenans as a bioink material for 3D printing in tissue engineering and regenerative medicine are systematically evaluated. We envisage some key hurdles and challenges in the commercialization of carrageenans as a versatile material for clinical practice. This comprehensive review of the intimate relationships among the structural features, unique rheological properties, and biofunctionality of carrageenans will provide novel insights into their biomedicine application potential.

Nasal sprays for treating COVID-19: a scientific note

Clinical management of COVID-19 has been a daunting task. Due to the lack of specific treatment, vaccines have been regarded as the first line of defence. Innate responses and cell-mediated systemic immunity, including serum antibodies, have been the primary focus of practically all studies of the immune response to COVID-19. However, owing to the difficulties encountered by the conventional route, alternative routes for prophylaxis and therapy became the need of the hour. The first site invaded by SARS-CoV-2 is the upper respiratory tract. Nasal vaccines are already in different stages of development. Apart from prophylactic purposes, mucosal immunity can be exploited for therapeutic purposes too. The nasal route for drug delivery offers many advantages over the conventional route. Besides offering a needle-free delivery, they can be self-administered. They present less logistical burden as there is no need for refrigeration. The present article focuses on various aspects of nasal spray for eliminating COVID-19.

Safety in Rats of a Novel Nasal Spray Formulation for the Prevention of Airborne Viral Infections

Hexedra+^® is a nasal spray containing hydroxypropyl methylcellulose, beta-cyclodextrin, and usnic acid. It has been developed with the aim of reducing the risk of transmission of airborne viral infections, with particular reference to influenza and COVID-19. As part of the preclinical development of the product, we carried out a study on thirty male Wistar rats divided into three study groups and treated with Hexedra+, an alternative formulation containing a double concentration of usnic acid (0.015% instead of 0.0075%) or saline solution. Products were administered at the dose of 30 μL into each nostril, three times a day for seven consecutive days by means of a micropipette. By the end of the treatment period, no significant changes were observed in body weight. Histological examination of nasal mucosa and soft organs did not show any significant difference in the three study groups. Serum transaminase level remained in the normal limit in all the animals treated. The serum level of usnic acid was measured in order to assess the absorption of the molecule through the nasal mucosa. By the end of the study period, the usnic acid serum level was negligible in all the animals treated. In conclusion, the safety profile of Hexedra+ appears favorable in the animal model studied.

Selective Formation of Osteogenic and Vasculogenic Tissues for Cartilage Regeneration

Tissue-engineered periosteum substitutes (TEPSs) incorporating hierarchical architecture with osteoprogenitor and vascular niches are drawing much attention as a promising tool to support functional cells in defined zones and nourish the cortical bone. Current TEPSs usually lack technologies to closely observe cell performance, especially at the cell contact interface between distinct compartments containing defined biological configurations and functions. Here, an electrodeposition strategy is reported, which enables the selective formation of TEPSs with osteoprogenitor and vascular niches in a multiphasic scaffold in combination with different human cell types for cartilage regeneration in an in vivo osteochondral defect model. Human umbilical vein endothelial cells (HUVECs), dermal fibroblasts (HDFs), and bone marrow mesenchymal stem cells (hMSCs) are used to mirror both the vascular and osteogenic niches, respectively. It is observed that the intrinsic viscoelastic nature of the porous solid matrix is essential to successfully induce angiogenesis. Coculture of hMSCs with functional cells (HUVECs/HDFs) in TEPSs also effectively promoted periosteal regeneration, including osteogenic and angiogenic processes. The osteoarthritis cartilage histopathology assessment and histologic/histochemical grading system data indicate that the TEPSs containing hMSCs/HUVECs/HDFs exhibit superior potential for cartilage regeneration.

A Supine Position and Dual-Dose Applications Enhance Spray Dosing to the Posterior Nose: Paving the Way for Mucosal Immunization

Delivering vaccines to the posterior nose has been proposed to induce mucosal immunization. However, conventional nasal devices often fail to deliver sufficient doses to the posterior nose. This study aimed to develop a new delivery protocol that can effectively deliver sprays to the caudal turbinate and nasopharynx. High-speed imaging was used to characterize the nasal spray plumes. Three-dimensional-printed transparent nasal casts were used to visualize the spray deposition within the nasal airway, as well as the subsequent liquid film formation and translocation. Influencing variables considered included the device type, delivery mode, release angle, flow rate, head position, and dose number. Apparent liquid film translocation was observed in the nasal cavity. To deliver sprays to the posterior nose, the optimal release angle was found to be 40° for unidirectional delivery and 30° for bidirectional delivery. The flow shear was the key factor that mobilized the liquid film. Both the flow shear and the head position were important in determining the translocation distance. A supine position and dual-dose application significantly improved delivery to the nasopharynx, i.e., 31% vs. 0% with an upright position and one-dose application. It is feasible to effectively deliver medications to the posterior nose by leveraging liquid film translocation for mucosal immunization.

Prediction of transport, deposition, and resultant immune response of nasal spray vaccine droplets using a CFPD-HCD model in a 6-year-old upper airway geometry to potentially prevent COVID-19

This study focuses on the transport, deposition, and triggered immune response of intranasal vaccine droplets to the angiotensin-converting-enzyme-2-rich region, i.e., the olfactory region (OR), in the nasal cavity of a 6-year-old female to possibly prevent corona virus disease 19 (COVID-19). To investigate how administration strategy can influence nasal vaccine efficiency, a validated multi-scale model, i.e., computational fluid-particle dynamics (CFPD) and host-cell dynamics (HCD) model, was employed. Droplet deposition fraction, size change, residence time, and the area percentage of OR covered by the vaccine droplets, and triggered immune system response were predicted with different spray cone angles, initial droplet velocities, and compositions. Numerical results indicate that droplet initial velocity and composition have negligible influences on the vaccine delivery efficiency to OR. In contrast, the spray cone angle can significantly impact the vaccine delivery efficiency. The triggered immunity was not significantly influenced by the administration investigated in this study due to the low percentage of OR area covered by the droplets. To enhance the effectiveness of the intranasal vaccine to prevent COVID-19 infection, it is necessary to optimize the vaccine formulation and administration strategy so that the vaccine droplets can cover more epithelial cells in OR to minimize the number of available receptors for SARS-CoV-2.

Can We Structure Biomaterials to Spray Well Whilst Maintaining Functionality?

Structured fluid biomaterials, including gels, creams, emulsions and particle suspensions, are used extensively across many industries, including great interest within the medical field as controlled release vehicles to improve the therapeutic benefit of delivered drugs and cells. Colloidal forces within these materials create multiscale cohesive interactions, giving rise to intricate microstructures and physical properties, exemplified by increasingly complex mathematical descriptions. Yield stresses and viscoelasticity, typically arising through the material microstructure, vastly improve site-specific retention, and protect valuable therapeutics during application. One powerful application route is spraying, a convenient delivery method capable of applying a thin layer of material over geometrically uneven surfaces and hard-to-reach anatomical locations. The process of spraying is inherently disruptive, breaking a bulk fluid in successive steps into smaller elements, applying multiple forces over several length scales. Historically, spray research has focused on simple, inviscid solutions and dispersions, far from the complex microstructures and highly viscoelastic properties of concentrated colloidal biomaterials. The cohesive forces in colloidal biomaterials appear to conflict with the disruptive forces that occur during spraying. This review explores the physical bass and mathematical models of both the multifarious material properties engineered into structured fluid biomaterials and the disruptive forces imparted during the spray process, in order to elucidate the challenges and identify opportunities for rational design of sprayable, structured fluid biomaterials.

Polymeric Materials as Indispensable Tools to Fight RNA Viruses: SARS-CoV-2 and Influenza A

Towards the end of 2019 in Wuhan, suspicions of a new dangerous virus circulating in the air began to arise. It was the start of the world pandemic coronavirus disease 2019 (COVID-19). Since then, considerable research data and review papers about this virus have been published. Hundreds of researchers have shared their work in order to achieve a better comprehension of this disease, all with the common goal of overcoming this pandemic. The coronavirus is structurally similar to influenza A. Both are RNA viruses and normally associated with comparable infection symptoms. In this review, different case studies targeting polymeric materials were appraised to highlight them as an indispensable tool to fight these RNA viruses. In particular, the main focus was how polymeric materials, and their versatile features could be applied in different stages of viral disease, i.e., in protection, detection and treatment.

Exploring the Role of Antiviral Nasal Sprays in the Control of Emerging Respiratory Infections in the Community

INTRODUCTION

The COVID-19 pandemic has demonstrated that there is an unmet need for the development of novel prophylactic antiviral treatments to control the outbreak of emerging respiratory virus infections. Passive antibody-based immunisation approaches such as intranasal antibody prophylaxis have the potential to provide immediately accessible universal protection as they act directly at the most common route of viral entry, the upper respiratory tract. The need for such products is very apparent for SARS-CoV-2 at present, given the relatively low effectiveness of vaccines to prevent infection and block virus onward transmission. We explore the benefits and challenges of the use of antibody-based nasal sprays prior and post exposure to the virus.

METHODS

The classic susceptible-exposed-infectious-removed (SEIR) mathematical model was extended to describe the potential population-level impact of intranasal antibody prophylaxis on controlling the spread of an emerging respiratory infection in the community.

RESULTS

Intranasal administration of monoclonal antibodies provides only a short-term protection to the mucosal surface. Consequently, sustained intranasal antibody prophylaxis of a substantial proportion of the population would be needed to contain infections. Post-exposure prophylaxis against the development of severe disease would be essential for the overall reduction in hospital admissions.

CONCLUSION

Antibody-based nasal sprays could provide protection against infection to individuals that are likely to be exposed to the virus. Large-scale administration for a long period of time would be challenging. Intranasal antibody prophylaxis alone cannot prevent community-wide transmission of the virus. It could be used along with other protective measures, such as non-pharmaceutical interventions, to bridge the time required to develop and produce effective vaccines, and complement active immunisation strategies.

Improving Nasal Protection for Preventing SARS-CoV-2 Infection

Airborne pathogens, including SARS-CoV-2, are mainly contracted within the airway pathways, especially in the nasal epithelia, where inhaled air is mostly filtered in resting conditions. Mucosal immunity developing after SARS-CoV-2 infection or vaccination in this part of the body represents one of the most efficient deterrents for preventing viral infection. Nonetheless, the complete lack of such protection in SARS-CoV-2 naïve or seronegative subjects, the limited capacity of neutralizing new and highly mutated lineages, along with the progressive waning of mucosal immunity over time, lead the way to considering alternative strategies for constructing new walls that could stop or entrap the virus at the nasal mucosa surface, which is the area primarily colonized by the new SARS-CoV-2 Omicron sublineages. Among various infection preventive strategies, those based on generating physical barriers within the nose, aimed at impeding host cell penetration (i.e., using compounds with mucoadhesive properties, which act by hindering, entrapping or adsorbing the virus), or those preventing the association of SARS-CoV-2 with its cellular receptors (i.e., administering anti-SARS-CoV-2 neutralizing antibodies or agents that inhibit priming or binding of the spike protein) could be considered appealing perspectives. Provided that these agents are proven safe, comfortable, and compatible with daily life, we suggest prioritizing their usage in subjects at enhanced risk of contagion, during high-risk activities, as well as in patients more likely to develop severe forms of SARS-CoV-2 infection.

Efficacy of Mouth Rinses and Nasal Spray in the Inactivation of SARS-CoV-2: A Systematic Review and Meta-Analysis of In Vitro and In Vivo Studies

Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) is a global and evolving pandemic associated with heavy health and financial burdens. Considering the oral cavity as the major reservoir for SARS-CoV-2, a systematic review and meta-analysis were conducted to assess the efficacy of mouth rinses and nasal sprays in reducing the salivary viral load of SARS-CoV-2. All in vivo and in vitro studies that assessed the virucidal efficacy of mouth rinses and nasal sprays against SARS-CoV-2 and were published in the English language from December 2019 to April 2022 were considered for analyses. Special Medical Subject Headings terms were used to search Pubmed, Scopus, Embase Ovid, and Web of Science databases. The toxicological data reliability assessment tool (ToxRToool) was used to assess the quality of the included studies. Thirty-three studies (11 in vivo and 22 in vitro) were deemed eligible for inclusion in this analysis. Results of the pooled data showed that povidone-iodine is the most efficacious intervention in vivo in terms of reducing the SARS-CoV-2 salivary viral load, followed by chlorhexidine. The mean difference in the viral load was 86% and 72%, respectively. Similarly, povidone-iodine was associated with the highest log₁₀ reduction value (LRV) in vitro, followed by cetylpyridinium chloride, (LRV = 2.938 (p < 0.0005) and LRV = 2.907 (p = 0.009), respectively). Povidone-iodine-based oral and nasal preparations showed favourable results in terms of reducing SARS-CoV-2 viral loads both in vivo and in vitro. Considering the limited number of patients in vivo, further studies among larger cohorts are recommended.

Layer-by-Layer Assembly of a Polysaccharide "Armor" on the Cell Surface Enabling the Prophylaxis of Virus Infection

Airborne pathogens, such as the world-spreading severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), cause global epidemics via transmission through the respiratory pathway. It is of great urgency to develop adequate interventions that can protect individuals against future pandemics. This study presents a nasal spray that forms a polysaccharide "armor" on the cell surface through the layer-by-layer self-assembly (LBL) method to minimize the risk of virus infection. The nasal spray has two separate components: chitosan and alginate. Harnessing the electrostatic interaction, inhaling the two polysaccharides alternatively enables the assembly of a barrier that reduces virus uptake into the cells. The results showed that this approach has no obvious cellular injury and endows cells with the ability to resist the infection of adenovirus and SARS-CoV-2 pseudovirus. Such a method can be a potential preventive strategy for protecting the respiratory tract against multiple viruses, especially the upcoming SARS-CoV-2 variants.

Engineered nasal dry powder for the encapsulation of bioactive compounds

In this review, we present the potential of nasal dry powders to deliver stable bioactive compounds and their manufacture using spray-drying (SD) techniques to achieve encapsulation. We also review currently approved and experimental excipients used for powder manufacturing for specific target drugs. Polymers, sugars, and amino acids are recommended for specific actions, such as mucoadhesive interactions, to increase residence time on the nasal mucosa; for example, high-molecular weight polymers, such as hydroxypropyl methylcellulose, or mannitol, which protect the bioactive compounds, increase their stability, and enhance drug absorption in the nasal mucosa; and leucine, which promotes particle formation and improves aerosol performance. Teaser: XXXX.

An easy-to-use antimicrobial hydrogel effectively kills bacteria, fungi, and influenza virus

Various drug resistant pathogens such as bacteria, fungi and viruses enter a host through different routes, which can lead to health-related problems and even fatalities. Propagation of these infectious microbes majorly occurs through the mucosal openings or upon topical contact. To curb their transmission or to cure infections associated with these pathogens, herein we describe the development of an antimicrobial hydrogel, based on a water soluble quaternary lipophilic polyethyleneimine derivative (QPEINH-C₆). The cationic polymer QPEINH-C₆ exhibited antibacterial activity against drug-resistant Gram-positive bacteria (MIC = 10-62 μg mL^-1) and Gram-negative bacteria (MIC = 117-123 μg mL^-1). The derivative showed killing of human pathogenic fungi (MIC = 58-67 μg mL^-1), including their clinical isolates. The rapid bactericidal and fungicidal nature were confirmed from the fast inactivation kinetics of bacterial cells (methicillin resistant S. aureus and vancomycin resistant S. aureus) within 3-6 hours and C. albicans within 1 h with ∼5-6 log reduction in the microbial burden. This antibacterial and antifungal cationic polymer was then used to construct an antimicrobial shear-thinning hydrogel (Bacfuvir), through non-covalent crosslinking with biocompatible gellan and polyvinyl alcohol (PVA). This hydrogel displayed ∼5-7 log reduction of numerous multidrug-resistant bacteria and their stationary phase cells which are insusceptible to conventional antibiotics. In addition, >99.9 % viable bacterial burden was reduced from preformed biofilm matrices of drug-resistant bacteria. Alongside, fluconazole-resistant C. albicans strains were killed completely within 15-60 min upon exposure to Bacfuvir gel. Most importantly, MRSA and C. albicans cells were reduced (3-4 log) in polymicrobial biofilms after hydrogel treatment. The hydrogel exhibited 99.9 % reduction of influenza viruses in a rapid manner. Due to the biocompatibility of Bacfuvir gel on topical application in a murine model and easy administration owing to its shear-thinning behaviour, this hydrogel can markedly contribute to mitigating drug-resistant bacterial, fungal and viral infections in healthcare settings.

Severe Acute Respiratory Syndrome Type 2-Causing Coronavirus: Variants and Preventive Strategies

COVID-19 vaccines have constituted a substantial scientific leap in countering severe acute respiratory syndrome type 2-causing coronavirus (SARS-CoV-2), and worldwide implementation of vaccination programs has significantly contributed to the global pandemic effort by saving many lives. However, the continuous evolution of the SARS-CoV-2 viral genome has resulted in different variants with a diverse range of mutations, some with enhanced virulence compared with previous lineages. Such variants are still a great concern as they have the potential to reduce vaccine efficacy and increase the viral transmission rate. This review summarizes the significant variants of SARS-CoV-2 encountered to date (December 2021) and discusses a spectrum of possible preventive strategies, with an emphasis on physical and materials science.

Advances in the Prophylaxis of Respiratory Infections by the Nasal and the Oromucosal Route: Relevance to the Fight with the SARS-CoV-2 Pandemic

In this time of COVID-19 pandemic, the strategies for prevention of the infection are a primary concern. Looking more globally on the subject and acknowledging the high degree of misuse of protective face masks from the population, we focused this review on alternative pharmaceutical developments eligible for self-defense against respiratory infections. In particular, the attention herein is directed to the nasal and oromucosal formulations intended to boost the local immunity, neutralize or mechanically "trap" the pathogens at the site of entry (nose or mouth). The current work presents a critical review of the contemporary methods of immune- and chemoprophylaxis and their suitability and applicability in topical mucosal dosage forms for SARS-CoV-2 prophylaxis.

Low Acyl Gellan as an Excipient to Improve the Sprayability and Mucoadhesion of Iota Carrageenan in a Nasal Spray to Prevent Infection With SARS-CoV-2

The COVID-19 global pandemic, as well as the widespread persistence of influenza and the common cold, create the need for new medical devices such as nasal sprays to prevent viral infection and transmission. Carrageenan, a sulfated polysaccharide, has a broad, non-pharmacological antiviral capacity, however it performs poorly in two key areas; spray coverage and mucoadhesion. Therefore gellan, another polysaccharide, was investigated as an excipient to improve these properties. It was found that viscoelastic relaxation time was the key predictor of spray coverage, and by reducing this value from 2.5 to 0.25 s, a mix of gellan and carrageenan gave more than four times the coverage of carrageenan alone (p < 0.0001). Gellan also demonstrated enhanced adhesion to a mucus analog that increased significantly with time (p < 0.0001), suggesting the development of specific gellan–mucin interactions. This property was conferred to carrageenan on mixing the two polymers. Together, this data suggests that gellan is a promising excipient to improve both sprayability and mucoadhesion of carrageenan for use in antiviral nasal sprays.

Antiviral Strategies Using Natural Source-Derived Sulfated Polysaccharides in the Light of the COVID-19 Pandemic and Major Human Pathogenic Viruses

Only a mere fraction of the huge variety of human pathogenic viruses can be targeted by the currently available spectrum of antiviral drugs. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak has highlighted the urgent need for molecules that can be deployed quickly to treat novel, developing or re-emerging viral infections. Sulfated polysaccharides are found on the surfaces of both the susceptible host cells and the majority of human viruses, and thus can play an important role during viral infection. Such polysaccharides widely occurring in natural sources, specifically those converted into sulfated varieties, have already proved to possess a high level and sometimes also broad-spectrum antiviral activity. This antiviral potency can be determined through multifold molecular pathways, which in many cases have low profiles of cytotoxicity. Consequently, several new polysaccharide-derived drugs are currently being investigated in clinical settings. We reviewed the present status of research on sulfated polysaccharide-based antiviral agents, their structural characteristics, structure-activity relationships, and the potential of clinical application. Furthermore, the molecular mechanisms of sulfated polysaccharides involved in viral infection or in antiviral activity, respectively, are discussed, together with a focus on the emerging methodology contributing to polysaccharide-based drug development.

Iota-Carrageenan Prevents the Replication of SARS-CoV-2 in a Human Respiratory Epithelium Cell Line in vitro

Iota-carrageenan is a sulfated polysaccharide extracted from red seaweeds, which, formulated into a nasal spray, has already been proven safe and effective in viral upper respiratory infections. In Calu-3, a human respiratory epithelium cell line, we explored the activity of a formula of iota-carrageenan and sodium chloride against SARS-CoV-2. In this study, the assayed formula, already approved as a nasal spray for human use, effectively inhibited SARS-CoV-2 infection, providing a more substantial reference for clinical studies or developments.

Nasally inhaled therapeutics and vaccination for COVID-19: Developments and challenges

The nose is the initial site of viral infection, replication, and transmission in the human body. Nasally inhaled vaccines may act as a promising alternative for COVID-19 management in addition to intramuscular vaccination. In this review, the latest developments of nasal sprays either as repurposed or antiviral formulations were presented. Nasal vaccines based on traditional medicines, such as grapefruit seed extract, algae-isolated carrageenan, and Yogurt-fermenting Lactobacillus, are promising and under active investigations. Inherent challenges that hinder effective intranasal delivery were discussed in detail, which included nasal device issues and human nose physiological complexities. We examined factors related to nasal spray administration, including the nasal angiotensin I converting enzyme 2 (ACE2) locations as the delivery target, nasal devices, medication translocation after application, delivery methods, safety issues, and other nasal delivery options. The effects of human factors on nasal spray efficacy, such as nasal physiology, disease-induced physiological modifications, intersubject variability, and mucociliary clearance, were also examined. Finally, the potential impact of nasal vaccines on COVID-19 management in the developing world was discussed. It is concluded that effective delivery of nasal sprays to ACE2-rich regions is urgently needed, especially in the context that new variants may become unresponsive to current vaccines and more refractory to existing therapies.

Fighting SARS-CoV-2 with green seaweed Ulva sp. extract: extraction protocol predetermines crude ulvan extract anti-SARS-CoV-2 inhibition properties in in vitro Vero-E6 cells assay

Due to the global COVID-19 pandemic, there is a need to screen for novel compounds with antiviral activity against SARS-COV-2. Here we compared chemical composition and the in vitro anti- SARS-COV-2 activity of two different Ulva sp. crude ulvan extracts: one obtained by an HCl-based and another one by ammonium oxalate-based (AOx) extraction protocols. The composition of the crude extracts was analyzed and their antiviral activity was assessed in a cytopathic effect reduction assay using Vero E6 cells. We show that the extraction protocols have a significant impact on the chemical composition, anti- SARS-COV-2 activity, and cytotoxicity of these ulvan extracts. The ulvan extract based on the AOx protocol had a higher average molecular weight, higher charge, and 11.3-fold higher antiviral activity than HCl-based extract. Our results strongly suggest that further bioassay-guided investigation into bioactivity of compounds found in Ulva sp. ulvan extracts could lead to the discovery of novel anti-SARS-CoV-2 antivirals.

Hydroxypropyl Methylcellulose-Based Nasal Sprays Effectively Inhibit In Vitro SARS-CoV-2 Infection and Spread

The ongoing coronavirus disease (COVID-19) pandemic has required a variety of non-medical interventions to limit the transmission of the causative agent, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). One such option is over-the-counter nasal sprays that aim to block virus entry and transmission within the nasal cavity. In this study, we assessed the ability of three hydroxypropyl methylcellulose (HPMC)-based powder nasal sprays, produced by Nasaleze, to inhibit SARS-CoV-2 infection and release in vitro. Upon application, the HPMC powder forms a gel-like matrix within the nasal cavity—a process we recapitulated in cell culture. We found that virus release from cells previously infected with SARS-CoV-2 was inhibited by the gel matrix product in a dose-dependent manner, with virus levels reduced by >99.99% over a 72 h period at a dose of 6.4 mg/3.5 cm². We also show that the pre-treatment of cells with product inhibited SARS-CoV-2 infection, independent of the virus variant. The primary mechanism of action appears to be via the formation of a physical, passive barrier. However, the addition of wild garlic provided additional direct antiviral properties in some formulations. We conclude that HPMC-based nasal sprays may offer an additional component to strategies to limit the spread of respiratory viruses, including SARS-CoV-2.

Can the Nasal Cavity Help Tackle COVID-19?

Despite the progress made in the fight against the COVID-19 pandemic, it still poses dramatic challenges for scientists around the world. Various approaches are applied, including repurposed medications and alternative routes for administration. Several vaccines have been approved, and many more are under clinical and preclinical investigation. This review aims to systemize the available information and to outline the key therapeutic strategies for COVID-19, based on the nasal route of administration.

Polymeric Materials as Potential Inhibitors Against SARS-CoV-2

Recently discovered SARS-CoV-2 caused a pandemic that triggered researchers worldwide to focus their research on all aspects of this new peril to humanity. However, in the absence of specific therapeutic intervention, some preventive strategies and supportive treatment minimize the viral transmission as studied by some factors such as basic reproduction number, case fatality rate, and incubation period in the epidemiology of viral diseases. This review briefly discusses coronaviruses' life cycle of SARS-CoV-2 in a human host cell and preventive strategies at some selected source of infection. The antiviral activities of synthetic and natural polymers such as chitosan, hydrophobically modified chitosan, galactosylated chitosan, amine-based dendrimers, cyclodextrin, carrageenans, polyethyleneimine, nanoparticles are highlighted in this article. Mechanism of virus inhibition, detection and diagnosis are also presented. It also suggests that polymeric materials and nanoparticles can be effective as potential inhibitors and immunization against coronaviruses which would further develop new technologies in the field of polymer and nanoscience.

Antiviral Activity of Carrageenans and Processing Implications

Carrageenan and carrageenan oligosaccharides are red seaweed sulfated carbohydrates with well-known antiviral properties, mainly through the blocking of the viral attachment stage. They also exhibit other interesting biological properties and can be used to prepare different drug delivery systems for controlled administration. The most active forms are λ-, ι-, and κ-carrageenans, the degree and sulfation position being determined in their properties. They can be obtained from sustainable worldwide available resources and the influence of manufacturing on composition, structure, and antiviral properties should be considered. This review presents a survey of the antiviral properties of carrageenan in relation to the processing conditions, particularly those assisted by intensification technologies during the extraction stage, and discusses the possibility of further chemical modifications.

Viral inhibitors derived from macroalgae, microalgae, and cyanobacteria: A review of antiviral potential throughout pathogenesis

Viruses are abiotic obligate parasites utilizing complex mechanisms to hijack cellular machinery and reproduce, causing multiple harmful effects in the process. Viruses represent a growing global health concern; at the time of writing, COVID-19 has killed at least two million people around the world and devastated global economies. Lingering concern regarding the virus' prevalence yet hampers return to normalcy. While catastrophic in and of itself, COVID-19 further heralds in a new era of human-disease interaction characterized by the emergence of novel viruses from natural sources with heretofore unseen frequency. Due to deforestation, population growth, and climate change, we are encountering more viruses that can infect larger groups of people with greater ease and increasingly severe outcomes. The devastation of COVID-19 and forecasts of future human/disease interactions call for a creative reconsideration of global response to infectious disease. There is an urgent need for accessible, cost-effective antiviral (AV) drugs that can be mass-produced and widely distributed to large populations. Development of AV drugs should be informed by a thorough understanding of viral structure and function as well as human biology. To maximize efficacy, minimize cost, and reduce development of drug-resistance, these drugs would ideally operate through a varied set of mechanisms at multiple stages throughout the course of infection. Due to their abundance and diversity, natural compounds are ideal for such comprehensive therapeutic interventions. Promising sources of such drugs are found throughout nature; especially remarkable are the algae, a polyphyletic grouping of phototrophs that produce diverse bioactive compounds. While not much literature has been published on the subject, studies have shown that these compounds exert antiviral effects at different stages of viral pathogenesis. In this review, we follow the course of viral infection in the human body and evaluate the AV effects of algae-derived compounds at each stage. Specifically, we examine the AV activities of algae-derived compounds at the entry of viruses into the body, transport through the body via the lymph and blood, infection of target cells, and immune response. We discuss what is known about algae-derived compounds that may interfere with the infection pathways of SARS-CoV-2; and review which algae are promising sources for AV agents or AV precursors that, with further investigation, may yield life-saving drugs due to their diversity of mechanisms and exceptional pharmaceutical potential.

Carrageenan-containing over-the-counter nasal and oral sprays inhibit SARS-CoV-2 infection of airway epithelial cultures

Pharmaceutical interventions are urgently needed to prevent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and transmission. As SARS-CoV-2 infects and spreads via the nasopharyngeal airways, we analyzed the antiviral effect of selected nasal and oral sprays on virus infection in vitro. Two nose sprays showed virucidal activity but were cytotoxic precluding further analysis in cell culture. One nasal and one mouth spray suppressed SARS-CoV-2 infection of TMPRSS2-expressing Vero E6 cells and primary differentiated human airway epithelial cultures. The antiviral activity in both sprays could be attributed to polyanionic ι- and κ-carrageenans. Thus, application of carrageenan-containing nasal and mouth sprays may reduce the risk of acquiring SARS-CoV-2 infection and may limit viral spread, warranting further clinical evaluation.