Properties of poly(lactic-co-glycolic acid) nanospheres containing protease inhibitors: Camostat mesilate and nafamostat mesilate

Repurpose but also (nano)-reformulate! The potential role of nanomedicine in the battle against SARS-CoV2

The coronavirus disease-19 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) has taken the world by surprise. To date, a worldwide approved treatment remains lacking and hence in the context of rapid viral spread and the growing need for rapid action, drug repurposing has emerged as one of the frontline strategies in the battle against SARS-CoV2. Repurposed drugs currently being evaluated against COVID-19 either tackle the replication and spread of SARS-CoV2 or they aim at controlling hyper-inflammation and the rampaged immune response in severe disease. In both cases, the target for such drugs resides in the lungs, at least during the period where treatment could still provide substantial clinical benefit to the patient. Yet, most of these drugs are administered systemically, questioning the percentage of administered drug that actually reaches the lung and as a consequence, the distribution of the remainder of the dose to off target sites. Inhalation therapy should allow higher concentrations of the drug in the lungs and lower concentrations systemically, hence providing a stronger, more localized action, with reduced adverse effects. Therefore, the nano-reformulation of the repurposed drugs for inhalation is a promising approach for targeted drug delivery to lungs. In this review, we critically analyze, what nanomedicine could and ought to do in the battle against SARS-CoV2. We start by a brief description of SARS-CoV2 structure and pathogenicity and move on to discuss the current limitations of repurposed antiviral and immune-modulating drugs that are being clinically investigated against COVID-19. This account focuses on how nanomedicine could address limitations of current therapeutics, enhancing the efficacy, specificity and safety of such drugs. With the appearance of new variants of SARS-CoV2 and the potential implication on the efficacy of vaccines and diagnostics, the presence of an effective therapeutic solution is inevitable and could be potentially achieved via nano-reformulation. The presence of an inhaled nano-platform capable of delivering antiviral or immunomodulatory drugs should be available as part of the repertoire in the fight against current and future outbreaks.

Nanomedicine strategies to target coronavirus

With the severe acute respiratory syndrome coronavirus (SARS-CoV) in 2002, the middle east respiratory syndrome CoV (MERS-CoV) in 2012 and the recently discovered SARS-CoV-2 in December 2019, the 21st first century has so far faced the outbreak of three major coronaviruses (CoVs). In particular, SARS-CoV-2 spread rapidly over the globe affecting nearly 25.000.000 people up to date. Recent evidences pointing towards mutations within the viral spike proteins of SARS-CoV-2 that are considered the cause for this rapid spread and currently around 300 clinical trials are running to find a treatment for SARS-CoV-2 infections. Nanomedicine, the application of nanocarriers to deliver drugs specifically to a target sites, has been applied for different diseases, such as cancer but also in viral infections. Nanocarriers can be designed to encapsulate vaccines and deliver them towards antigen presenting cells or function as antigen-presenting carriers themselves. Furthermore, drugs can be encapsulated into such carriers to directly target them to infected cells. In particular, virus-mimicking nanoparticles (NPs) such as self-assembled viral proteins, virus-like particles or liposomes, are able to replicate the infection mechanism and can not only be used as delivery system but also to study viral infections and related mechanisms. This review will provide a detailed description of the composition and replication strategy of CoVs, an overview of the therapeutics currently evaluated in clinical trials against SARS-CoV-2 and will discuss the potential of NP-based vaccines, targeted delivery of therapeutics using nanocarriers as well as using NPs to further investigate underlying biological processes in greater detail.

Effect of dual delivery of antibiotics (vancomycin and cefazolin) and BMP-7 from chitosan microparticles on Staphylococcus epidermidis and pre-osteoblasts in vitro

The main aims of this manuscript are to: i) determine the effect of commonly used antibiotics to treat osteoarticular infections on osteoblast viability, ii) study the dual release of the growth factor (BMP-7) and antibiotics (vancomycin and cefazolin) from chitosan microparticles iii) demonstrate the bioactivity of the antibiotics released in vitro on Staphylococcus epidermidis. The novelty of this work is dual delivery of growth factor and antibiotic from the chitosan microparticles in a controlled manner without affecting their bioactivity. Cefazolin and vancomycin have different therapeutic concentrations for their action in vivo and therefore, two different concentrations of the drugs were used. Osteoblast cytotoxicity test concluded that cefazolin concentrations of 50 and 100μg/ml were found to have positive influence on osteoblast proliferation. A significant increase in osteoblast proliferation was observed in the presence of cefazolin and BMP-7 in comparison with BMP-7 alone group; indicating cefazolin might play a role in osteoblast proliferation. On the other hand, vancomycin concentration of 1000μg/ml was found to significantly reduce (p<0.01) osteoblast proliferation in comparison with controls. The microbial study indicated that cefazolin at a minimum concentration of 21.5μg/ml could inhibit ~85% growth of S. epidermidis, whereas vancomycin at a concentration of 30μg/ml was found to inhibit ~80% bacterial growth.

Externally controlled triggered-release of drug from PLGA micro and nanoparticles

Biofilm infections are extremely hard to eradicate and controlled, triggered and controlled drug release properties may prolong drug release time. In this study, the ability to externally control drug release from micro and nanoparticles was investigated. We prepared micro/nanoparticles containing ciprofloxacin (CIP) and magnetic nanoparticles encapsulated in poly (lactic-co-glycolic acid) PLGA. Both micro/nanoparticles were observed to have narrow size distributions. We investigated and compared their passive and externally triggered drug release properties based on their different encapsulation structures for the nano and micro systems. In passive release studies, CIP demonstrated a fast rate of release in first 2 days which then slowed and sustained release for approximately 4 weeks. Significantly, magnetic nanoparticles containing systems all showed ability to have triggered drug release when exposed to an external oscillating magnetic field (OMF). An experiment where the OMF was turned on and off also confirmed the ability to control the drug release in a pulsatile manner. The magnetically triggered release resulted in a 2-fold drug release increase compared with normal passive release. To confirm drug integrity following release, the antibacterial activity of released drug was evaluated in Pseudomonas aeruginosa biofilms in vitro. CIP maintained its antimicrobial activity after encapsulation and triggered release.

An automated two-phase system for hydrogel microbead production

Polymeric beads have been used for protection and delivery of bioactive materials, such as drugs and cells, for different biomedical applications. Here, we present a generic two-phase system for the production of polymeric microbeads of gellan gum or alginate, based on a combination of in situ polymerization and phase separation. Polymer droplets, dispensed using a syringe pump, formed polymeric microbeads while passing through a hydrophobic phase. These were then crosslinked, and thus stabilized, in a hydrophilic phase as they crossed through the hydrophobic-hydrophilic interface. The system can be adapted to different applications by replacing the bioactive material and the hydrophobic and/or the hydrophilic phases. The size of the microbeads was dependent on the system parameters, such as needle size and solution flow rate. The size and morphology of the microbeads produced by the proposed system were uniform, when parameters were kept constant. This system was successfully used for generating polymeric microbeads with encapsulated fluorescent beads, cell suspensions and cell aggregates proving its ability for generating bioactive carriers that can potentially be used for drug delivery and cell therapy.

Preparation and evaluation of PLGA microparticles as carrier for the pulmonary delivery of rhIL-2 : I. Effects of some formulation parameters on microparticle characteristics

In this study, recombinant human interleukin-2 (rhIL-2) containing poly(lactic-co-glycolic acid) (PLGA) microparticles were prepared for pulmonary administration by modified w/o/w double emulsion solvent extraction method and the effects of various formulation parameters on the physicochemical properties of the microparticles were investigated. Microparticles in suitable size for pulmonary administration (4.02 µm) were obtained by increasing dichloromethane volume used in the organic phase. Also, a very high encapsulation efficiency (99.22%) value could be reached in these microparticles. In the sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis, rhIL-2 extracted from microparticles having a similar band with native rhIL-2 showed that the protein was not affected by the encapsulation process. The release curves of microparticles exhibited a biphasic fashion, characterized by a fast release phase at initial 1 day, followed by a slower one on the remaining days. Bioactivity investigations using T cells show that rhIL-2 encapsulated in PLGA microparticles retain their biological activity.

Novel antibacterial nanofibrous PLLA scaffolds

In order to achieve high local bioactivity and low systemic side effects of antibiotics in the treatment of dental, periodontal and bone infections, a localized and temporally controlled delivery system is crucial. In this study, a three-dimensional (3-D) porous tissue engineering scaffold was developed with the ability to release antibiotics in a controlled fashion for long-term inhibition of bacterial growth. The highly soluble antibiotic drug, doxycycline (DOXY), was successfully incorporated into PLGA nanospheres using a modified water-in-oil-in-oil (w/o/o) emulsion method. The PLGA nanospheres (NS) were then incorporated into prefabricated nanofibrous PLLA scaffolds with a well interconnected macro-porous structure. The release kinetics of DOXY from four different PLGA NS formulations on a PLLA scaffold was investigated. DOXY could be released from the NS-scaffolds in a locally and temporally controlled manner. The DOXY release is controlled by DOXY diffusion out of the NS and is strongly dependent upon the physical and chemical properties of the PLGA. While PLGA50-6.5K, PLGA50-64K, and PLGA75-113K NS-scaffolds discharge DOXY rapidly with a high initial burst release, PLGA85-142K NS-scaffold can extend the release of DOXY to longer than 6weeks with a low initial burst release. Compared to NS alone, the NS incorporated on a 3-D scaffold had significantly reduced the initial burst release. In vitro antibacterial tests of PLGA85 NS-scaffold demonstrated its ability to inhibit common bacterial growth (S. aureus and E. coli) for a prolonged duration. The successful incorporation of DOXY onto 3-D scaffolds and its controlled release from scaffolds extends the usage of nano-fibrous scaffolds from the delivery of large molecules such as growth factors to the delivery of small hydrophilic drugs, allowing for a broader application and a more complex tissue engineering strategy.