Development and validation of a novel sensitive UV-direct capillary electrophoresis method for quantification of alendronate in release studies from biomaterials

Fe(III)-mediated reversible catalytic activity of MoS2 nanozymes for bisphosphonate drug sensing

Peroxidase-like activity of MoS₂ quantum dots (QDs) can be reversibly regulated by means of Fe³⁺/alendronate sodium (ALDS)-induced aggregation/disaggregation of the QDs in solution. Specifically, Fe³⁺ can selectively aggregate the MoS₂ QDs and thus greatly enhance their peroxidase-like activity, while such enhancement can be inhibited in the presence of ALDS owing to the competitive coordination of ALDS with Fe³⁺. By regulating the enzyme-like activity of MoS₂ QDs, different colorimetric signal of a typical substrate of horseradish peroxidase, 3,3΄,5,5΄-tetramethylbenzidine, can be measured in the presence of H₂O₂. Based on this mechanism, we develop a colorimetric approach for the determination of ALDS and further applied in quality control of pharmaceutical products, utilizing either smartphone or UV-vis spectrometer as a readout. This detection method is rapid and selective, where derivatization of ALDS before detection is not needed. Such a smartphone-based colorimetric detection platform is promising to be applied in point-of-care testing at home, small clinics, or underdeveloped regions.

Magnetic solid phase extraction followed by in-situ derivatization with core-shell structured titanium dioxide coated ferriferrous oxide microspheres for determination of alendronate in plasma

In this study, for the first time, magnetic solid phase extraction (MSPE) was combined with in-situ derivatization to determine alendronate in plasma. TiO₂ coated Fe₃O₄ microspheres (denoted as Fe₃O₄@TiO₂) were synthesized via polydopamine coating, titanium ions immobilizing and calcination steps. The as-prepared microspheres could selectively extract alendronate and be quickly isolated from plasma. The drug-adsorbed Fe₃O₄@TiO₂ microspheres were then directly incubated in derivatization reagent solution to perform novel in-situ derivatization and elution procedure, in which the derivatized alendronate lost its affinity to TiO₂ and was spontaneously eluted for further LC-MS/MS detection. Satisfactory results were obtained on the creative attempt to couple dispersive magnetic solid phase extraction with in-situ derivatization. The developed method was validated and demonstrated good linearity (0.05-500 ng mL^-1), low detection limit (20 pg mL^-1), great accuracy (100.6% to 105.3%) and precision (RSDs<5.27%). Manual operation and analysis time could be greatly reduced compared to other reported methods. The method was successfully applied to a pharmacokinetic study in beagle dogs.