Emerging Role of Enzyme-Immobilized Nanocarriers in Osteoporosis: Advances and Challenges.

Osteoporosis (OP) is a common bone disease that involves low bone mass and high risk of fracture mainly in older men and women and perimenopausal years. Although conventional therapies provide good therapeutic effects, they have numerous limitations, including poorly targeted and systemic administration and severe side effects. Recent developments in nanotechnology enabled design of enzyme-immobilized nanocarriers as experimental platforms to enhance the delivery of therapeutic agents to bone tissue. This review pays special attention to the development of these multifunctional systems that can transport anti-osteoporotic agents and carry enzymes to stimulate bone formation. Enzymes like alkaline phosphatase for mineralization, superoxide dismutase for reactive oxygen species reduction, and cathepsin K inhibitors for osteoclast regulation are highlighted to demonstrate rationale behind enzyme immobilization. Enzyme immobilization promotes local bone regeneration by increasing enzyme stability and activity at target site offering more sustained therapeutic effect in OP therapy. Polymeric NP and liposomes like nanocarriers are well explained along with their various mechanisms such as stability, bioavailability controlling and release kinetics. Further, we review the current literature for the recent in vivo and in vitro studies highlighting the potential of these systems in stimulating osteoblast function and suppressing osteoclast-mediated bone resorption. Areas for future research include improving carrier design for increased targetability and exploring the clinical translation of these nanocarrier systems for OP management.