Facile synthesis of highly tunable monodispersed calcium hydroxide composite particles by using a two-step ion exchange reaction.

"Calcium hydroxide [Ca(OH)2]" is a medicament frequently used for antimicrobial purposes in endodontic procedures, or it is used as a toxic-waste adsorbent in industry. Ca(OH)2 particles produced through conventional methods are size untunable and have a wide size distribution and polygonal shape. In this paper, a novel and facile approach involving template-mediated synthesis and two-step ion exchange is proposed for uniform size Ca(OH)2 composite particles generation. "Sodium-alginate (Na-alginate)" was used as a precursor, and monodisperse Na-alginate emulsions were formed through needle droplet or droplet microfluidic technology. After the first ion exchange step with the Ca2+ ions, "calcium-alginate (Ca-alginate)" particles were obtained. The Ca-alginate particles were intermediate reaction products and were designed to be the templates for ensuring the spherical shape and size of products. The OH- ions were used for the second ion exchange step to fabricate Ca(OH)2 composite particles. The results revealed that the Ca(OH)2 composite particles were size tunable, had a spherical shape, and were monodisperse (with a relative standard deviation of less than 8%). The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay revealed that the Ca(OH)2 composite particles were potential biocompatible materials.

Microfluidic assisted synthesis of silver nanoparticle-chitosan composite microparticles for antibacterial applications.

Silver nanoparticle (Ag NP)-loaded chitosan composites have numerous biomedical applications; however, fabricating uniform composite microparticles remains challenging. This paper presents a novel microfluidic approach for single-step and in situ synthesis of Ag NP-loaded chitosan microparticles. This proposed approach enables obtaining uniform and monodisperse Ag NP-loaded chitosan microparticles measuring several hundred micrometers. In addition, the diameter of the composites can be tuned by adjusting the flow on the microfluidic chip. The composite particles containing Ag NPs were characterized using UV-vis spectra and scanning electron microscopy-energy dispersive X-ray spectrometry data. The characteristic peaks of Ag NPs in the UV-vis spectra and the element mapping or pattern revealed the formation of nanosized silver particles. The results of antibacterial tests indicated that both chitosan and composite particles showed antibacterial ability, and Ag NPs could enhance the inhibition rate and exhibited dose-dependent antibacterial ability. Because of the properties of Ag NPs and chitosan, the synthesized composite microparticles can be used in several future potential applications, such as bactericidal agents for water disinfection, antipathogens, and surface plasma resonance enhancers.