Fabrication and characteristics of new quaternized chitosan nanocapsules loaded with thymol or thyme essential oil as effective SARS-CoV-2 inhibitors.

This research explores the potential of encapsulating thyme essential oil (TEO) and thymol (TH) into quaternized chitosan nanocapsules to combat SARS-CoV-2. Initially, the bioactive materials, TH and TEO, were extracted from Thymus vulgaris and then structurally and phytochemically characterized by spectral and GC-MS analyses. Meanwhile, O-quaternized ultrasonic-mediated deacetylated chitosan (QUCS) was successfully synthesized and characterized. Lastly, nanobiocomposites (NBCs; NBC1 and NBC2) were fabricated using QUCS as a scaffold to encapsulate either TEO or TH, with the mediation of Tween 80. By encapsulating these bioactive materials, we aim to enhance their efficacy and targeted delivery, bioavailability, stability, and anti-COVID properties. The new NBCs were structurally, morphologically, and physically characterized. Incorporating TEO or TH into QUCS significantly increased ZP values to ±53.1 mV for NBC1 and ±48.2 mV for NBC2, indicating superior colloidal stability. Interestingly, Tween 80-QUCS provided outstanding packing and release performance, with entrapment efficiency (EE) and loading capacity (LC) values of 98.2% and 3.7% for NBC1 and 83.7% and 1.9% for NBC2. The findings of in vitro antiviral studies not only highlight the potential of these nanobiocomposites as potential candidates for anti-COVID therapies but also underscore their selectivity in targeting SARS-CoV-2.