ABSTRACT
The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has forced the development of direct-acting antiviral drugs due to the coronavirus disease 2019 (COVID-19) pandemic. The main protease of SARS-CoV-2 is a crucial enzyme that breaks down polyproteins synthesized from the viral RNA, making it a validated target for the development of SARS-CoV-2 therapeutics. New chemical phenotypes are frequently discovered in natural goods. In the current study, we used a fluorogenic assay to test a variety of natural products for their ability to inhibit SARS-CoV-2 Mpro. Several compounds were discovered to inhibit Mpro at low micromolar concentrations. It was possible to crystallize robinetin together with SARS-CoV-2 Mpro, and the X-ray structure revealed covalent interaction with the protease's catalytic Cys145 site. Selected potent molecules also exhibited antiviral properties without cytotoxicity. Some of these powerful inhibitors might be utilized as lead compounds for future COVID-19 research.
ABSTRACT
The most prevalent conditions among ocular surgery and COVID-19 patients are fungal eye infections, which may cause inflammation and dry eye, and may cause ocular morbidity. Amphotericin-B eye drops are commonly used in the treatment of ocular fungal infections. Lactoferrin is an iron-binding glycoprotein with broad-spectrum antimicrobial activity and is used for the treatment of dry eye, conjunctivitis, and ocular inflammation. However, poor aqueous stability and excessive nasolacrimal duct draining impede these agens' efficiency. The aim of this study was to examine the effect of Amphotericin-B, as an antifungal against Candida albicans, Fusarium, and Aspergillus flavus, and Lactoferrin, as an anti-inflammatory and anti-dry eye, when co-loaded in triblock polymers PLGA-PEG-PEI nanoparticles embedded in P188-P407 ophthalmic thermosensitive gel. The nanoparticles were prepared by a double emulsion solvent evaporation method. The optimized formula showed particle size (177.0 ± 0.3 nm), poly-dispersity index (0.011 ± 0.01), zeta-potential (31.9 ± 0.3 mV), and entrapment% (90.9 ± 0.5) with improved ex-vivo pharmacokinetic parameters and ex-vivo trans-corneal penetrability, compared with drug solution. Confocal laser scanning revealed valuable penetration of fluoro-labeled nanoparticles. Irritation tests (Draize Test), Atomic force microscopy, cell culture and animal tests including histopathological analysis revealed superiority of the nanoparticles in reducing signs of inflammation and eradication of fungal infection in rabbits, without causing any damage to rabbit eyeballs. The nanoparticles exhibited favorable pharmacodynamic features with sustained release profile, and is neither cytotoxic nor irritating in-vitro or in-vivo. The developed formulation might provide a new and safe nanotechnology for treating eye problems, like inflammation and fungal infections.
ABSTRACT
During the SARS-CoV2 pandemic mRNA vaccines in the form of lipid nanoparticles (LNPs) containing the mRNA, have set the stage for a new area of vaccines. Analytical methods to quantify changes in size and structure of LNPs are crucial, as changes in these parameters could have implications for potency. We investigated the application of sedimentation velocity analytical ultracentrifugation (SV-AUC) as quantitative stability-indicating method to detect structural changes of mRNA-LNP vaccines upon relevant stress factors (freeze/thaw, heat and mechanical stress), in comparison to qualitative dynamic light scattering (DLS) analysis. DLS was capable to qualitatively determine size and homogeneity of mRNA-LNPs with sufficient precision. Stress factors, in particular freeze/thaw and mechanical stress, led to increased particle size and content of larger species in DLS and SV-AUC. Changes upon heat stress at 50 °C were only detected as increased flotation rates by SV-AUC. In addition, SV-AUC was able to observe changes in particle density, which cannot be detected by DLS. In conclusion, SV-AUC can be used as a highly valuable quantitative stability-indicating method for characterization of LNPs.
ABSTRACT
Obesity is a metabolic condition that accounts for life-threatening disorders like cancer, cardiovascular diseases, and type-2 diabetes. There are several anti-obesity drugs currently available on the market, but many of them show poor bioavailability due to low water solubility. Several attempts have been made by researchers to improve the solubility of orally administered drugs, but many of them did not work properly. Herein, we introduced a block copolymer micelle consisting of poly (lactic acid)-co-poly (ethylene glycol) to improve the solubility of the anti-obesity drug "Fenofibrate”. The block copolymer was synthesized using the polycondensation method, while the micelle was formed when water was added dropwise to the copolymer. Finally, laser light scattering and DLS analysis were used to confirm the micelle formation. The size of the micelle increased from 158 nm to 249 nm after the fenofibrate drug loading inside the hydrophobic core. The polymer PLA-co-PEG can be used as a carrier for orally administered fenofibrate drugs in the future for better water solubility and efficiency. © The Electrochemical Society
ABSTRACT
Due to the unprecedented and ongoing nature of the coronavirus outbreak, the development of rapid immunoassays to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and its highly contagious variants is an important and challenging task. Here, we report the development of polyclonal antibody-functionalized spherical gold nanoparticle biosensors as well as the influence of the nanoparticle sizes on the immunoassay response to detect the SARS-CoV-2 spike protein by dynamic light scattering. By monitoring the increment in the hydrodynamic diameter (ΔDH) by dynamic light scattering measurements in the antigen-antibody interaction, SARS-CoV-2 S-protein can be detected in only 5 min. The larger the nanoparticles, the larger ΔDH in the presence of spike protein. From adsorption isotherm, the calculated binding constant (K D ) was 83 nM and the estimated limit of detection was 13 ng/mL (30 pM). The biosensor was stable up to 90 days at 4 °C. Therefore, the biosensor developed in this work could be potentially applied as a fast and sensible immunoassay to detect SARS-CoV-2 infection in patient samples.
ABSTRACT
Dynamic light scattering (DLS) is widely used for analyzing biological polymers and colloids. Its application to nanoparticles in medicine is becoming increasingly important with the recent emergence of prominent lipid nanoparticle (LNP)-based products, such as the SARS-CoV-2 vaccines from Pfizer, Inc.-BioNTech (BNT162b2) and Moderna, Inc. (mRNA-1273). DLS plays an important role in the characterization and quality control of nanoparticle-based therapeutics and vaccines. However, most DLS instruments have a single detection angle theta, and the amplitude of the scattering vector, q, varies among them according to the relationship q = (4 pi n/lambda (0)) sin(theta/2), where lambda (0) is the laser wavelength. Results for identical, polydisperse samples among instruments of varying q yield different hydrodynamic diameters, because, as particles become larger they scatter less light at higher q, so that higher-q instruments will under-sample large particles in polydisperse populations, and report higher z-average diffusion coefficients, and hence smaller effective hydrodynamic diameters than lower-q instruments. As particle size reaches the Mie regime the scattering envelope manifests angular maxima and minima, and the monotonic decrease of average size versus q is lost. The discrepancy among instruments of different q is hence fundamental, and not merely technical. This work examines results for different q-value instruments, using mixtures of monodisperse latex sphere standards, for which experimental measurements agree well with computations, and also polydisperse solutions of physically-degraded LNPs, for which results follow expected trends. Mie effects on broad unimodal populations are also considered. There is no way to predict results between two instruments with different q for samples of unknown particle size distributions. Initial analysis of the polydispersity index among different instruments shows a technical difference due to method of autocorrelation analysis, in addition to the fundamental q-effect.