Arginine Hydrochloride

Arginine hydrochloride (ArgHCl) effectively reduces the high viscosity of concentrated antibody solutions for subcutaneous injection. Bovine gamma globulin (BGG) at 250 mg/mL and human gamma globulin (HGG) at 292 mg/mL exhibited viscosity above the acceptable threshold of 50 cP at physiological pH. Addition of 1000 mM ArgHCl lowered viscosity below this threshold, while lysine, glycine, and sodium chloride increased viscosity. ArgHCl also reduced viscosity at acidic and alkaline pH. Notably, ArgHCl decreased viscosity specifically for antibodies (BGG, HGG, and IgG) but not for globular proteins such as α-amylase and α-chymotrypsin. At low additive concentrations, viscosity reduction is attributed to electrostatic interaction shielding. At higher concentrations, specific interactions—likely cation-π interactions between the guanidinium group of arginine and aromatic residues on antibodies—play a dominant role.

Fig. 1 Arginine decreases the solution viscosity of antibodies. (Inoue N.; et al. 2014)

A multifunctional hybrid hydrogel P(M-Arg/NIPAAm) was developed as a wound dressing with temperature response, anti-protein adsorption, and antibacterial properties. The hydrogel was synthesized via free radical copolymerization of methacrylate arginine (M-Arg) and N-isopropyl acrylamide (NIPAAm). To enhance antimicrobial activity, chlorhexidine diacetate (CHX) was preloaded into the hydrogel and polyhexamethylene guanidine phosphate (PHMG) was grafted onto its surface. The hydrogel exhibited a homogeneous porous structure. NIPAAm improved transparency, mechanical properties, and temperature-responsive drug release. The zwitterionic arginine component provided biocompatibility and resistance to protein adsorption and bacterial adhesion. Antimicrobial assessment, cell viability tests, and in vivo wound healing in a mouse model demonstrated that the hydrogel is nontoxic, antibacterial, and accelerates full-thickness wound healing. This hybrid hydrogel combines biocompatibility, environmental responsiveness, biodegradability, anti-protein adsorption, and antimicrobial properties, making it a promising candidate for advanced wound dressing applications.

Fig. 2 Arginine-NIPAAm hybrid hydrogel as wound dressing. (Wu D Q.; et al. 2018)