Bombyx mori Chitosan–Caffeine Nanocapsules: Formation, Structural Features, and Physicochemical Properties

Abstract

This study aimed to engineer Bombyx mori chitosan–caffeine nanocapsules via a self-assembly approach and to comprehensively characterize their structural architecture, physicochemical properties, and release kinetics under precisely controlled pH conditions. Chitosan–caffeine nanocapsules were synthesized in aqueous medium at low temperature under controlled acidic conditions (pH 3.2 and 4.5), achieving yields of 91–94 %. Their physicochemical properties were analyzed using UV and FTIR spectroscopy, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The results showed that hydrogen bonding and electrostatic interactions between the protonated amino groups of chitosan and the carbonyl groups of caffeine promoted the formation of spherical and oval nanostructures with diameters in the range of 100–400 nm. Spectroscopic analysis confirmed the intermolecular interactions responsible for encapsulation, while X-ray diffraction indicated a decrease in caffeine crystallinity after incorporation into the polymer matrix. SEM and TEM micrographs demonstrated efficient encapsulation of caffeine within the chitosan matrix and confirmed the formation of stable core–shell nanostructures. Release profile analysis showed that approximately 20 % of the total caffeine content was released from the chitosan nanocapsules over the monitored period, confirming their controlled release behavior. These chitosan-caffeine nanocapsules hold potential for future use in the development of drugs with prolonged release properties.