Covalent bonding of PMMA, PBMA, and poly(HEMA) to hydroxyapatite particles

Abstract

In our earlier study, we showed that the surface hydroxyl groups of hydroxyapatite have the ability to react with organic isocyanate groups. In this study, the feasibility of grafting poly(methyl methacrylate) (PMMA), poly(n-butyl methacrylate) (PBMA), and Poly(hydroxyethyl methacrylate) [poly(HEMA)] by using the reaction of isocyanate groups with the hydroxyl groups on the surface of HA was investigated. Double bonds were introduced to the surface of HA via the coupling reaction of isocyanateoethyl methacrylate (ICEM) with HA, or through hexamethylene diisocyanate (HMDI) with hydroxyethyl methacrylate (HEMA) and HA, followed by radical polymerization in MMA, BMA, or HEMA. Infrared spectra indicated the existence of polymers on the surfaces of HA. Thermogravimetric analysis also confirmed the presence of grafted polymers on the surface of HA powder particles (20-26 wt%). The polymers gave typical PMMA, PBMA, or poly(HEMA) infrared spectra, with the exception of amide bands, a result of the coupling reaction of ICEM or HMDI with hydroxy groups of HA or HEMA. Therefore it is concluded that the polymers were chemically bonded to the surface of HA through the isocyanate groups of ICEM or HMDI.

Synthesis of a Covalent Epirubicin-(C3-amide)-Anti-HER2/neuImmunochemotherapeutic Utilizing a UV-Photoactivated Anthracycline Intermediate

“…The lack of a requirement for protein thiolation is in obvious contrast to most other synthesis regimens that utilize heterobifunctional reactants similar to SMCC, 7,107-109 EMCH, 9,10,26 or PMPI 30,[110][111][112] that contain a sulfhydryl-reactive moiety. Pre-thiolation of immunoglobulin, F(ab') 2 , Fab, or other biological proteins is usually required due to the relatively low number of nonsterically hindered sulfhydryl groups in the form of reduced cysteine amino acid residues (e.g., R-SH) available within their amino acid sequence.…”

“…6,39 In the preparation of some covalent immunochemotherapeutics, relatively higher anthracycline-immunoglobulin molar-incorporation-indexes results in only modest declines in immunoreactivity (e.g., 86% for a 73:1 ratio) but disproportionate declines in anti-neoplastic activity down to potency levels substantially lower than those found with nonconjugated ''free'' anthracycline. 39 However, in contrast to succinimidyl-4-(N-maleimidomethyl)-cyclohexane-1-carboxylate (SMCC), 7,107-109 EMCH, [8][9][10]26,142,143 or PMPI 30,[110][111][112] the utilization of succinimidyl 4,4-azipentanoate allows greater flexibility for increasing the chemotherapeutic molarincorporation-index while synthesizing covalent immunochemotherapeutics without the simultaneous creation of harsher reaction conditions. Therefore the major risk of compromising the biological integrity (antigen binding avidity) of epirubicin-(C 3 -amide)-[anti-HER2/neu] synthesized with succinimidyl 4,4-azipentanoate is almost entirely associated with introducing too many chemotherapeutic moieties into the Fab antigen bindings regions of the immunoglobulin molecule.…”

Calcium orthophosphate-based biocomposites and hybrid biomaterials

“…FTIR spectroscopy seems to be the major investigation tool of a possible chemical bonding among the phases in calcium orthophosphate-based biocomposites and hybrid biomaterials [220,280,287,289,382,420,502,517,526,529,536,539,541,544,549,556,565,570,595,633,666,667,726,910,911]. For example, the characteristic bands at 2918, 2850, and 1472 cm -1 for the hydrocarbon backbone of PE appeared to have zero shift in an HA/PE biocomposite.…”

“…A hexamethylene diisocyanate coupling agent was used to bind PEG/PBT (Polyactive TM ) block copolymers [234] and other polymers [910] to HA filler particles. Thermogravimetric and infrared analysis demonstrated that the polymers were chemically bonded to the HA particles through the isocyanate groups, making it a suitable approach to improve the adhesion [910].…”

“…Thermogravimetric and infrared analysis demonstrated that the polymers were chemically bonded to the HA particles through the isocyanate groups, making it a suitable approach to improve the adhesion [910]. Other researchers used glutaraldehyde as a crosslinked reagent in various calcium orthophosphate-based biocomposites [388,392,500,502,503,520,525,585,621,646,649,917].…”