PMMA Microcapsules for the Inactivation of SARS-CoV-2

Surface disinfection currently plays a decisive role in the epidemiological situation caused by the SARS-CoV-2 coronavirus. However, most disinfection products available on the market have a high evaporation rate and only an immediate action and not continuous, creating the need for a high frequency of disinfection. To overcome this limitation, in the present work, poly(methyl methacrylate) (PMMA) microcapsules were developed with an active agent (hydrogen peroxide) encapsulated, which has the ability to inactivate/neutralize the SARS-CoV-2 virus. PMMA-H₂O₂ microcapsules have a spherical shape and a smooth structure with low porosity and were successfully attached to nonwoven fabrics, as observed from scanning electron microscopy. The thermogravimetric analysis shows that PMMA-H₂O₂ microcapsules have high thermal stability and can increase the stability of H₂O₂. Nonfabric substrates functionalized with PMMA-H₂O₂ microcapsules were tested by a highly sensitive and specific reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR)-based method to evaluate antiviral activity through the degradation of SARS-CoV-2 deoxyribonucleic acids. The highest percentage of viral nucleic acid elimination was obtained when exposing the viral sample for 1 h to PMMA-H₂O₂ microcapsules, resulting in an elimination of >97% of the coronavirus. In addition, the microcapsules are stable over a period of three weeks and retain the ability to eliminate SARS-CoV-2. Hence, it is demonstrated that this microcapsule system is efficient for SARS-CoV-2 elimination and inherent surface disinfection.

Physicochemical characterization of spray-dried PLGA/PEG microspheres, and preliminary assessment of biological response

CONTEXT

The use of spray-drying to prepare blended PLGA:PEG microspheres with lower immune detection.

OBJECTIVE

To study physical properties, polymer miscibility and alveolar macrophage response for blended PLGA:PEG microspheres prepared by a laboratory-scale spray-drying process.

METHODS

Microspheres were prepared by spray-drying 0-20% w/w ratios of PLGA 65:35 and PEG 3350 in dichloromethane. Particle size and morphology was studied using scanning electron microscopy. Polymer miscibility and residual solvent levels evaluated by thermal analysis (differential scanning calorimetry - DSC and thermogravimetric analysis - TGA). Immunogenicity was assessed in vitro by response of rat alveolar macrophages (NR8383) by the MTT-based cell viability assay and reactive oxygen species (ROS) detection.

RESULTS

The spray dried particles were spherical, with a size range of about 2-3 µm and a yield of 16-60%. Highest yield was obtained at 1% PEG concentration. Thermal analysis showed a melting peak at 59 °C (enthalpy: 170.61 J/g) and a degradation-onset of 180 °C for PEG 3350. PLGA 65:35 was amorphous, with a Tg of 43 °C. Blended PLGA:PEG microspheres showed a delayed degradation-onset of 280 °C, and PEG enthalpy-loss corresponding to 15% miscibility of PEG in PLGA. NR8383 viability studies and ROS detection upon exposure to these cells suggested that blended PLGA:PEG microspheres containing 1 and 5% PEG are optimal in controling cell proliferation and activation.

CONCLUSION

This research establishes the feasibility of using a spray-drying process to prepare spherical particles (2-3 µm) of molecularly-blended PLGA 65:35 and PEG 3350. A PEG concentration of 1-5% was optimal to maximize process yield, with minimal potential for immune detection.