Synergistic effects of hydroxyapatite, montmorillonite and carboxymethylcellulose in pH-responsive nanocomposites for teriparatide delivery

Despite significant progress, the approach to drug delivery in bone tissue engineering encounters unique challenges due to the intricate bone anatomy. In response, a novel pH-responsive hydrogel nanocomposite (CMC/MMT/HAP) has been developed for precise delivery of Teriparatide (PTH (1-34)), with the primary objective of enhancing drug solubility, stability, and mitigating degradation. This nanocomposite provides an efficient injectable dosage regimen, addressing side effects, safety concerns, and the inconvenience of frequent injections. The nanocomposites underwent comprehensive characterization through various analytical techniques, including X-ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), Zeta potential analysis, Dynamic Light Scattering (DLS), and Field-Emission Scanning Electron Microscopy (FE-SEM). The nanocomposites displayed an average crystallite diameter of 29.2 ± 1.4 nm. The PTH (1-34)-loaded nanocarrier exhibited a hydrodynamic size of 193.48 ± 3.8 nm and a surface charge of -40 mV. Furthermore, the loading and encapsulation efficiencies were determined to be 38% and 82%, respectively. Utilizing the dialysis method in conjunction with High-Performance Liquid Chromatography (HPLC) analysis, drug diffusion experiments unveiled a sustained-release pattern. As the pH decreased from 7.4 to 5.6, there was a corresponding increase in PTH (1-34) diffusion. After 24 h, drug release was higher in the acidic pH (58%) compared to the physiological pH (32%). This trend persisted, culminating in 98.5% and 64% release percentages after 240 h. Swelling tests demonstrated that the hydrogel exhibited a high fluid absorption capacity in physiological-like conditions, a property that facilitates enhanced tissue integration and supports sustained, diffusion-controlled drug release. The alkaline phosphatase (ALP) activity assay showed a marked increase in osteogenic differentiation, with the nanocomposite exhibiting the highest activity, highlighting its potential for bone regeneration. The biocompatibility of the PTH (1-34)-loaded nanocarrier was evaluated using the MTT assay with L929, HEK-293, and SaOS-2 cell lines as test models.The results affirmed its non-toxic nature and demonstrated its ability to stimulate cell proliferation and differentiation. Drawing insights from these findings, the CMC/MMT/HAP@PTH (1-34) nanocomposite, as a drug delivery system, presents a highly efficient and biocompatible approach to enhance therapeutic efficacy, thereby overcoming limitations associated with drug delivery.