Size-directed preparation of chitosan-carrageenan nanoparticles using dynamic light scattering for sustainable materials development

The sustainable development of biopolymer-based nanoparticles using marine wastes and algal polysaccharides can significantly push the advancement of green chemistry and nanotechnology by reducing waste and using safer chemicals. This study uses a dynamic light scattering (DLS)-guided sequential approach for optimizing chitosan-carrageenan nanoparticles to produce a sustainable nanocarrier while minimizing reliance on the traditional trial-and-error methods. By adopting a systematic approach, this study ensures that the nanoparticles achieve the desired properties while minimizing waste in the production process. Chitosan is a biopolymer derived from crustacean waste while carrageenan can be extracted from seaweeds, an abundant marine resource. These raw materials can be used as encapsulating materials to address the limitations of bioactive compounds in drug delivery and other applications. The process involves selecting the appropriate chitosan molecular weight, carrageenan type, chitosan: carrageenan ratio, crosslinker type, and crosslinker concentration. The four-step formulation process identified a 5:1:1:3 ratio of low molecular weight chitosan, κ-carrageenan, sodium tripolyphosphate (STPP), and calcium chloride (CaCl₂) as optimal, yielding nanoparticles with a hydrodynamic diameter of approximately 350 nm as measured by DLS. FTIR analysis confirmed successful chitosan–carrageenan nanoparticle formation, while AFM and TEM imaging revealed loosely aggregated particles with average sizes of ∼150 nm in AFM and below 100 nm in TEM. This biopolymer-based nanoparticle can have applications in drug delivery, active packaging, and other related industries while supporting multiple Sustainable Development Goals (SDGs 2, 3, 6, and 12) and contributes to waste reduction and the advancement of eco-friendly materials science.