ABSTRACT This study developed environmentally responsive layer‐by‐layer self‐assembled (CS/SA‐PGPR) n ‐CS microcapsules based on chitosan (CS) and sodium alginate (SA) for the controlled release of plant growth‐promoting rhizobacteria (PGPR). The effects of the number of assembled layers ( n ), pH, salt concentration, and temperature on swelling and PGPR release were systematically investigated. Increasing n significantly enhanced the crosslinking density and structural compactness, thereby reducing swelling and markedly inhibiting initial PGPR release. XRD analysis confirmed the progressive accumulation of the cross‐linked network, as the diffraction peak at 32°—attributed to ordered calcium alginate formation via Ca 2+ COO − interaction—intensified with n . High‐salt environments weakened polyelectrolyte interactions through charge shielding, intensifying swelling and accelerating release. Under alkaline conditions, initial release was slow due to residual free amino groups; however, release rates exceeded those under neutral and acidic conditions over time. Temperature significantly influenced release kinetics, with the fastest release at 37°C and negligible release at 4°C. This microcapsule system exhibits excellent responsiveness to pH, ionic strength, and temperature, demonstrating its potential for smart controlled‐release agricultural microbial formulations.
Yang et al. (Sun,) studied this question.