Development and characterization of manganese-doped hydroxyapatite-incorporated wet-electrospun polycaprolactone scaffolds

Bioceramic-incorporated polymer-based scaffolds have gained more interest as a promising and effective approach in bone tissue engineering (BTE) applications. This study is the first to investigate the role of incorporated manganese-doped hydroxyapatite (Mn-HA) and gelatin coating in increased bioactivity and biological properties, specifically the cell attachment potencies of three-dimensional (3D) porous electrospun polycaprolactone (PCL). In this context, novel 3D porous composite scaffolds were synthesized by wet electrospinning of PCL incorporated with Mn-HA. The scaffolds were then coated with a thin gelatin layer to enhance the cell adhesion capacity. The effects of Mn-HA and the gelatin coating were evaluated in terms of structural, physicochemical, and biological properties. The results demonstrated that Mn-HA was successfully synthesized with doping of 2 mol% Mn, with MnSO₄(manganese sulfate) and MnCl₂(manganese chloride) precursors. Mn-HA powder with a MnSO₄precursor indicated better cell viability results. Therefore, Mn-HA/PCL scaffolds with 2.5% and 5% (w/w) bioceramic content were prepared with the MnSO₄precursor. The scaffolds' porosity increased from 24% (PCL/gelatin group) to approximately 34% in both the 2.5% and 5% (w/w) bioceramic-containing groups. The addition of Mn-HA powder improved the<i>in vitro</i>bioactivity and degradation rate of the scaffolds. Specifically, the 5% and 2.5% (w/w) Mn-HA incorporated scaffolds indicated 40% and 30% weight loss after 21 d of incubation, respectively. In contrast to the PCL/gelatin and HA-containing groups, the Mn-doped HA containing scaffolds exhibited a weight loss of around 17%-20%, indicating a decrease in degradation. The presence of the Mn-HA powder and gelatin coating elevated the cell viability results significantly, as opposed to the PCL scaffolds. Incorporation of 5% (w/w) Mn-HA improved the alkaline phosphatase activity and intracellular calcium levels, contrary to other groups. Thus, the incorporation of Mn-doped HA and gelatin into the PCL scaffold supports the potency towards properties required for BTE applications and suggests it as a prospective biomaterial for further evaluations.