Recent advances in development and application of derivatization reagents having a benzofurazan structure: a brief overview: Recent advances in benzofurazan derivatization reagents

Heterobifunctional cross-linker with dinitroimidazole and azide modules for protein and oligonucleotide functionalization

Dinitroimidazole (DNIm) was recently identified as a powerful bioconjugation agent that could selectively modify thiol over amine on biomolecules at an ultrahigh speed in an aqueous buffer. However, its derivative containing a DNIm module and a terminal alkyne module failed to construct functional agents bearing a DNIm warhead via the CuAAC reaction. To solve this problem, a heterobifunctional cross-linker was designed and synthesized by linking a DNIm module with an azide module via an oxoaliphatic amido bond spacer arm. Its two modules, DNIm and azide, reacted with a thiol and cyclooctyne, respectively, in an orthogonal way. The cross-linker facilitated the preparation of various functional agents bearing a DNIm warhead via SPAAC reaction and was further applied to protein functionalization (including biotinylation and fluorescence labeling) and oligonucleotide functionalization (including PEGylation, oligonucleotide-peptide and oligonucleotide-protein conjugate). Thus, the cross-linker not only provided convenient access to those functional agents bearing a DNIm warhead but also combined DNIm chemistry with click chemistry of SPAAC to enlarge their respective application range in the bioconjugation field.

Evaluation of 4-fluoro-7-nitrobenzofurazan as a dual-function chromogenic and fluorogenic probe for tulathromycin and its innovative utility for development of two eco-friendly and high-through microwell assays for analysis of pharmaceutical formulations

Tulathromycin is a triamilide antibacterial drug which has been approved for use in the European Union and the United States for the treatment and prevention of bovine respiratory diseases. The aim of this study was the development of two innovative microwell spectrometric (photometric and fluorometric) assays for determination of tulathromycin in its pharmaceutical formulations. To achieve this goal, 4-fluoro-7-nitrobenzofurazan was investigated as a dual-function chromogenic and fluorogenic probe for tulathromycin. The reaction between tulathromycin and 4-fluoro-7-nitrobenzofurazan proceeded smoothly in an alkaline medium, resulting in the formation of a colored and fluorescent product. The product displayed a maximum light absorption at 475 nm and emitted fluorescence at 545 nm when excited at 475 nm. Extensive investigations were conducted to optimize the factors affecting the tulathromycin /4-fluoro-7-nitrobenzofurazan reaction, and the optimal conditions were established. Using these optimized conditions, both microwell-based photometric and fluorometric assays were developed. The calibration curves relating the absorbance and fluorescence intensities of the reaction product with the corresponding tulathromycin concentrations were generated. The absorbance-concentration relationship was found to be linear within a tulathromycin concentration range of 10-400 µg mL-1, with a limit of quantitation of 6.2 µg mL-1. On the other hand, the fluorescence-concentration relationship was linear within a concentration range of 0.04-1.2 µg mL-1, with a limit of quantitation of 0.06 µg mL-1. Rigorous validations of both assays' procedures were performed, and both assays were successfully employed for the analysis of tulathromycin-containing pharmaceutical formulations (injections) with satisfactory accuracy and precision. The ecologically friendly assessment of both assays demonstrated their compliance with the principles of green analytical chemistry approaches. Moreover, the proposed microwell-based assays enabled the simultaneous analysis of multiple samples using small volumes, enabling high-throughput analysis. In conclusion, this study represents the first evaluation of 4-fluoro-7-nitrobenzofurazan as a probe with dual functionality for the microwell-based photometric and fluorometric analysis of tulathromycin. The developed assays serve as valuable analytical tools for ensuring the quality of tulathromycin 's pharmaceutical formulations.

A dual-function chromogenic and fluorogenic benzofurazan probe for plazomicin and its innovative utility for development of two microwell assays with high throughput for analysis of drug substance and pharmaceutical formulations

Plazomicin (PLZ) is a novel aminoglycoside which has been recently approved by The US Food and Drug Administration for the treatment of complicated urinary tract infections including acute pyelonephritis, caused by certain Enterobacteriaceae, in adult patients with limited or no options for alternative treatment. This study focuses on the development of microwell-based photometric and fluorometric assays for the quantitative determination of PLZ in its bulk drug substance and commercial pharmaceutical formulations (Zemedri® injections). Both assays utilize the dual-function chromogenic and fluorogenic properties of the 4-fluoro-7-nitrobenzofurazan (NBD-F) probe. The reaction between PLZ and NBD-F, conducted in a borate buffer at pH 8, resulted in the formation of a colored and fluorescent reaction product. The product exhibited maximum light absorption at 473 nm and emitted fluorescence at 541 nm when excited at 473 nm. Factors influencing the reaction between PLZ and NBD-F were thoroughly investigated, and optimal conditions were determined. Under the optimized reaction conditions, calibration curves were generated to establish the relationship between absorbance and fluorescence intensities of the reaction product with the corresponding PLZ concentrations. The absorbance-concentration relation was linear in a PLZ concentration range of 20-800 μg mL-1 with a limit of quantitation of 25 μg mL-1, while the fluorescence-concentration relation was linear in the concentration range of 0.05-1.5 μg mL-1 with a limit of quantitation of 0.08 μg mL-1. Both assays underwent validation and were successfully applied to the quantitation of PLZ in its bulk drug substance and pharmaceutical formulations (injections) with satisfactory accuracy and precision. The eco-friendliness/greenness assessment of the assays demonstrated that both assays comply with the requirements of green analytical chemistry approaches. Furthermore, the proposed microwell assay plates allowed for the simultaneous handling of numerous samples with micro-volumes, enabling high-throughput analysis. In conclusion, this study represents the first evaluation of NBD-F as a dual-function probe for the microwell-based photometric and fluorometric determination of PLZ. The developed assays serve as valuable analytical tools for the quality control of PLZ's bulk drug substance and pharmaceutical formulations.

Organic nanoparticles with ultrahigh quantum yield and aggregation-induced emission characteristics for cellular imaging and real-time two-photon lung vasculature imaging

Organic nanoparticles with a high quantum yield of 90% and aggregation-induced emission characteristics were prepared for cellular imaging and real-time two-photon vasculature imaging of the lungs.