Fructose-Based Metal–Organic Framework as a Means to Synthesize Sr-Loaded Chitosan Nanospheres with NLO Properties for Theranostic Applications in Radiotherapy

Chitosan is a biodegradable polymer derived from chitin, which is a versatile material for various biological applications due to its attractive properties such as biocompatibility, biodegradability, and non-toxicity. Furthermore, chitosan possesses Second Harmonic Generation (SHG) properties that are useful for biosensing applications. In this work, we explored the possibility of exploiting chitosan-based nanospheres as SHG-based biosensors, and also as carriers of 89Sr radionuclide, an Active Pharmaceutical Ingredient (API) for radiopharmaceutical treatments in cancer therapy. To opportunely load the Sr ion on the nanospheres, we used a fructose-based Metal–Organic Framework, with the formula [Sr(C6H12O6)2(H2O)2]Cl2·H2O, because the sugar was able to drive the Sr ions on the chitosan matrix. Sr-loaded chitosan nanospheres were synthesized, characterized, and their SHG response was measured. The results encouraged us to propose the nanospheres for theranostic purposes, i.e., valuable for both therapeutic and diagnostic applications at the same time.