Preparation and Controlled Drug Release Characteristics of Thermoresponsive PEG/Poly (NIPAM-co-AMPS) Hydrogels

Prevention of Collagen-Induced Platelet Binding and Activation by Thermosensitive Nanoparticles

“…This would allow them to present the proper collagen-binding sites once suspended in an aqueous solution, and allow for competitive binding of the SILY to the exposed collagen while the nanoparticles would provide steric hindrance and prevent platelets from accessing any additional binding sites on the collagen (46,54). We found that while there is some electrostatic association between the particle and the SILY, a majority of the peptide is successfully covalently crosslinked to the particle using BMPH (Table II), resulting in a permanent stable attachment of the SILY peptide T h e r e t e n t i o n o f t h e i r a n i o n i c c h a rg e a nd thermosensitive properties allows the modified nanoparticles to load and release the therapeutic peptide KAFAK, with a final loading efficiency of 32%, and a burst release of over 70% of the final amount of KAFAK released occurring within the first 12 h. This is slightly lower than the loading efficiencies reported by other sulfated poly(NIPAM) nanoparticles (29,43) and can most likely be attributed partial charge neutralization by the attached SILY as well as the surface-bound SILY hindering diffusion of the KAFAK into the particle's core. Decreased core loading could also explain the relatively rapid KAFAK release, as a large portion of the peptide would be near the surface of the particle allowing for rapid diffusion into the surrounding environment.…”

“…Additionally, poly(NIPAm) is readily copolymerized with acrylic acid (AAc), which adds easily modified carboxylic acid functional groups to the backbone of the particle, allowing for the addition of targeting ligands while simultaneously increasing the colloidal stability of the nanoparticle (38)(39)(40)(41)(42). In addition to carboxylic acid, the charged sulfated comonomer 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) has been added to poly(NIPAm) nanoparticles, resulting in colloidally stable, hemocompatible sulfated poly(NIPAm-AMPS) nanoparticles (29,43,44).…”

“…Poly(N-isopropylacrylamide) (poly(NIPAm)) is a thermosensitive polymer that has been extensively studied for use in biomedical applications such as tissue engineering, drug delivery, and injectable hydrogels (26)(27)(28)(29), as it exhibits a physiologically relevant lower volume phase transition temperature (VPTT) around 33°C (30)(31)(32)(33). This temperature sensitivity makes crosslinked poly(NIPAm) nanoparticles ideal in vivo drug carriers as they are soluble in aqueous solutions at temperatures below the VPTT, allowing for efficient loading of water-soluble therapeutics via passive diffusion (31,34).…”

Electrically induced swelling and methylene blue release behaviour of poly (N-isopropylacrylamide-co-acrylamido-2-methylpropyl sulphonic acid) hydrogels

“…2. In addition, temperature-responsive swelling/ de-swelling behaviour of PEG/poly (NIPAM-co-AMPS) hydrogels was also reported in our previous article [37]. The hydrogels have exhibited a temperature-responsive behaviour dependent on the amount of AMPS present in hydrogels.…”

“…The hydrogels were prepared by solution polymerization using PEG as the macroinitiator as described in our previous article [37]. The macroinitiator solution was prepared by dissolving 1 g of PEG in 10 mL of water, and to this solution, 4 mL of 0.1 M (NH 4 ) 2 Ce(NO 3 ) 6 solution prepared in 1 N nitric acid was added and stirred for 5 min.…”