Impact of two different hesperidin forms loaded on nanoscale modified borate bioglass scaffolds on rat critical-sized calvarial defects

Bone defects remain a major clinical challenge because of their limited self-healing capacity. This study aimed primarily to evaluate whether nanoscale modified borate bioglass scaffolds (MBBGS) could enhance the delivery of hesperidin (HPN), an antioxidant flavonoid, to bone defects, and secondarily to compare the osteogenic effects of micro- and nano-sized HPN (mHPN and nHPN) on bone regeneration. Scaffolds were fabricated and fully characterized. Fifty-six healthy male albino rats were anesthetized, and bilateral critical-sized calvarial defects were created. The rats were divided into four groups: control (empty defects), MBBGS alone, MBBGS loaded with mHPN, and MBBGS loaded with nHPN. The animals were euthanized at the end of the 2nd and 6th weeks postoperatively. The skulls were harvested and processed for radiological, histological, and immunohistochemical analyses. Radiographic evaluation showed progressive defect closure over time, with the greatest reduction in defect size observed in the MBBGS + nHPN group compared to the other groups. Histologically, the MBBGS + nHPN group revealed the greatest osteogenic impact and significantly increased osteopontin (OPN) immunoreactivity, followed by MBBGS + mHPN and MBBGS groups, while the control group exhibited minimal bone healing and weak OPN reactivity. In conclusion, the newly fabricated MBBGS effectively promoted calvarial bone regeneration, which was further enhanced by loading with nHPN.