Popcorn-like Particles from an Amino Acid, Poly(L-Cysteine) as Drug Delivery System with Blood-Compatible, Bio-Compatible, Antibacterial, and Antioxidant Properties

A facile and single-step synthesis of poly(L-Cysteine) (p(L-Cys)) particles through microemulsion polymerization using tetrakis(hydroxymethyl) phosphonium chloride (THPC) as crosslinker is accomplished for the first time. The L-Cys:THPC ratio in p(L-Cys) particles was calculated as 80:20% (by weight) with elemental analyses, and the generation of p(L-Cys) particles was confirmed. SEM imaging revealed a popcorn-like morphology of the p(L-Cys) particles with a 1–20 µm particle size range. The isoelectric point of p(L-Cys) particles was determined at pH 1.15 via zeta potential measurements. The hydrolytic degradation of p(L-Cys) particles was determined as about 85% within 3 h (by weight). The p(L-Cys) particles displayed excellent blood compatibility with a hemolysis % ratio of