pH effects on zeta potential and antibacterial activity of chitosan-based nano-microparticles

MESAS, FLORENCIA; TORRES NICOLINI, A.; TERRILE, MARIA CECILIA; SALCEDO, M.F.; ÁLVAREZ, VERA A; CASALONGUE, CLAUDIA; MENDIETA, JULIETA RENEE

Maceio

Congreso; XXI B-MRS Meeting 2023; 2023

Brazilian Materials Research Society

Chitosan (CS)-based materials have emerged as a promising alternative to replace toxic chemical compounds. These materials exert antibacterial activity (AbA) against phytopathogens [1]. The antibacterial properties of CS nano-microparticles (CS-NP/MP) depend on several intrinsic and extrinsic factors such as size and morphology of the CS-NP/MP, zeta potential (ZP), interacting pH, presence, and nature of functionalized compounds in the CS-NP/MP [2]. In this study, we describe the synthesis and physico-chemical characterization of a set CS-NP/MP. Moreover, we evaluate the effect of pH on the ZP of the CS-NP/MPs and its impact on their AbA. The particles were produced by ionic gelation using tripolyphosphate (TPP) as a crosslinker, and during the synthesis process, different parameters were assayed (CS:TPP ratio, type, and agitation time). The obtained particles, designed as CS-NP, CS-MP1, and CS-MP2, exhibited similar sizes but contrasting ZP values (13.9, 33.7, and 4.78 mV, respectively). Our results showed the ZP of CS-NP/MP and its AbA against Pseudomonas syringae pv. tomato DC3000 decrease with increasing pH of the medium. Therefore, we describe an important role of pH to determine the ZP of the materials and consequently the electrostatic interaction between the positively charged polymer and the negatively charged surface of the microorganism. We discuss our findings in light of the material properties and opportunities to use CS-NP/MP as a new type of biomaterial in modern agriculture.