Experimental investigation of interfaces in hydroxyapatite/polyacrylic acid/polycaprolactone composites using photoacoustic FTIR spectroscopy

Abstract

Molecular interactions in hydroxyapatite (HAP) polymer composites have been studied using photoacoustic spectroscopy. HAP is mineralized by wet precipitation under two conditions: first is in the absence of polyacrylic acid (PAAc) (ex-situ HAP) and second in the presence of PAAc (in-situ HAP). Porous and solid composites of ex-situ and in-situ HAP with polycaprolactone (PCL) have also been made to evaluate their applicability as bone scaffolds. Photoacoustic Fourier transform infrared (PA-FTIR) spectroscopy studies indicate that both in-situ and ex-situ HAP have HPO4 (2-) in their structure, which leads to Ca2+ deficiency. During crystallization of in-situ HAP, PAAc dissociates to form carboxylate ions, which binds to calcium ions and act as suitable site for nucleation for HAP crystallization. PA-FTIR spectra of porous and solid composites indicate that porous composites adsorb more water, which is hydrogen bonded with carbonyl of PCL. Mechanical tests on solid samples indicate that ex-situ HAP/PCL composites have higher elastic modulus than in-situ HAP/PCL composites. However, in case of porous composites, in-situ HAP/PCL composites are found to have higher elastic modulus. In-situ HAP is chemically and structurally different from ex-situ HAP. This modified HAP causes variation in microstructure of porous composite and hence alteration of its load transfer mechanisms and hence mechanical properties.

Polymeric nanoparticles modified with fatty acids encapsulating betamethasone for anti-inflammatory treatment

“…Empty OA NP + BTMA (1:1, 584 w/w) showed both specific bands for BTMA (IR (KBr) ν 3404 cm -1 , 1657 cm -1 , 1605 cm -585 1 , and 1047 cm -1 ) and for NPs (IR (KBr) ν 1726 cm -1 and 1187 cm -1 ). Specific band for 586 polycaprolactone (1730 cm -1 for C=O stretching) was visible for every sample with 587 nanoparticles, varying from 1326 to 1327 cm -1 , which may indicate a carbonyl bond 588 interaction site (Verma, Katti and Katti 2006). This was the main visible band for the 589 nanoparticles, since polycaprolactone is the more abundant compound.…”

In vitro study of polycaprolactone/bioactive glass composite coatings on corrosion and bioactivity of pure Mg

“…4 shows the spectra for 5% PCL and 5% PCL/nBG coatings, as well as for pure Mg. The characteristic bands for carbonyl groups at 1160cm −1 (C-O-C carbonyl stretching) [56][57], 1240cm −1 (C-O-C stretching) [62] and 1720 cm −1 (C-O carbonyl stretching) [63][64][65] and aliphatic groups at 2947 cm −1 (asymmetric CH 2 stretching) and 2865 cm −1 (symmetric CH 2 stretching) [66] were observed for PCL and PCL/nBG coatings. There was no band for nBG detected in PCL/nBG coating, as the concentration of the nBG added (0.5 wt%) M a n u s c r i p t is too low to be quantified by FTIR spectroscopy.…”

Cerium, gallium and zinc containing mesoporous bioactive glass coating deposited on titanium alloy

“…The FTIR spectra (see Fig. 4) of PCL and blank, cerium, gallium, zinc MBG-PCL show characteristic bands of CH 2 at 2950 and 2853 cm −1 , C O at 1720 cm −1 and carboxylic group at 1250 and 1170 cm −1 for polycaprolactone, respectively [33,34]. Furthermore, the absorption band at 1035 and 442 cm −1 are assigned to the Si O Si asymmetric stretch and the band centered at ∼800 cm −1 could be ascribed to Si O symmetric stretch [35].…”