Supramolecular polycaprolactone nanocomposite based on functionalized hydroxyapatite

Abstract

Arms bearing ureido-pyrimidinone functional groups with self-association capability (through quadruple hydrogen bonds) were successfully grafted onto hydroxyapatite nanoparticles. The supramolecularly modified nanoparticles (nHApUPy) exhibited enhanced colloidal stability compared to the original hydroxyapatite nanoparticles and were uniformly dispersed in supramolecular polycaprolactone in PCL(UPy)2/HApUPy nanocomposites at different filler loadings. The combined atomic force microscopy, mechanical, and rheological analyses confirmed a high degree of compatibility of HApUPy nanoparticles with the polymer matrix. The temperature dependence of the supramolecular structure in PCL(UPy)2/HApUPy nanocomposites was determined from dynamic rheological measurements at two different temperatures, 60°C and 85°C. The osteocompatibility of the nanocomposite containing HApUPy nanoparticles was compared to the pure polymer. The preliminary cell results clearly confirm that the supramolecular nanocomposites are nontoxic and biocompatible. Therefore, it is postulated that supramolecular nanocomposites provide a new way of tuning the mechanical properties of the supramolecular polymers, particularly supramolecular polycaprolactones.

Engineered electrospun poly(caprolactone)/polycaprolactone-g-hydroxyapatite nano-fibrous scaffold promotes human fibroblasts adhesion and proliferation

“…This is due to improved compatibility between the matrix and the filler and enhanced adhesion at the organic-inorganic inter-phase as well as the uniform dispersion of HAp at nano-scale within the polymer matrix. Similar mechanical behavior was previously reported by Shokrollahi et al, when tried to improve HAp/PCL inter-phase in a PCL/HAp supramolecular nano-composite[10].InsertFigure 3…”

“…Colloidal stability of HAp nano-particles is important because of the particles tendency to aggregate in effect of van derWaals interactions as well as hydrogen bond formation between the surface hydroxyl groups. These interactions result in rapid precipitation in organic solution [10]. On the other hand, when nano-composites are made by solvent casting, a high colloidal stability is required to synthesize homogenous bulk nano-composites [10].…”

“…These interactions result in rapid precipitation in organic solution [10]. On the other hand, when nano-composites are made by solvent casting, a high colloidal stability is required to synthesize homogenous bulk nano-composites [10]. In other words, rapid precipitation of inorganic fillers in organic solvents cause inconsistent particle distribution within the polymer matrix.…”

“…Nano-composites of PCL, as a biodegradable polymer and HAp as a bioactive ceramic, have offered versatile mechanical and biological properties [10,11]. PCL is an FDA approved biodegradable polymer with non-toxic degradation by-products and slow degradation rate [12].…”

“…Shokrollahi P., et al, have recently chemically immobilized supramolecularly functionalized short chain alkane moieties on both nano-(nHAp), and micron-sized hydroxyapatite (mHAp). Thay showed that both the dispersability and the bioactivity have improved in both the PCL/nHAp and the PCL/mHAp composites, significantly [10][11]19]. It might be argued therefore, that the long chain PCL grafts, while improving the dispersion, may reduce exposed surface area of the HAp nano-particles effectively.…”