RESUMEN
Molecular recognition plays an important role in biological systems and relates to a wide range of applications in disease diagnostics and therapeutics. Studies based on steady state or ensemble analysis may mask critical dynamic information of single recognition events. Here we report a study of monitoring the transient molecular recognition via single particle motion. We utilized a super-localization imaging methodology, to comprehensively evaluate the rotational Brownian motion of a single nanoparticle in spatial-temporal-frequential domain, with a spatial accuracy ~20 nm and a temporal resolution of ~10 ms. The transient moment of molecular encountering was captured and different binding modes were discriminated. We observed that the transient recognition events were not static states of on or off, but stochastically undergoes dynamical transformation between different binding modes. This study improves our understanding about the dynamic nature of molecular recognition events beyond the ensemble characterization via binding constant.
RESUMEN
The small absorption cross sections of most molecules led to the low sensitivity of traditional optical absorption spectroscopy. This obstacle might be overcome by applying the near-field plasmon resonance energy transfer (PRET) between plasmonic nanoparticle and surrounding molecules. In this work, we utilized PRET-based spectroscopy on single gold nanostars to study the specific biomolecule recognition and enzyme kinetics choosing biotin-SA pair and DNase I as models. By analyzing the changes of absorption spectra for black hole quencher 3 (BHQ3), derived from spectra difference, we explored the kinetics of specific biomolecule recognition and enzyme digestion in different physiological environment, and we found that the viscosities of media and the sizes of molecules play vital role in biomolecular recognition and enzyme digestion. Compared with the traditional optical absorption spectroscopy techniques, PRET-based spectroscopy offers a nanoscopic resolution owing to the small size of the probe, is more sensitive and achieves detection on the order of hundreds or even dozens of molecules, and can achieve high selectivity due to the specific biomolecular recognition. This method might be used in the fields of molecular diagnostics, drug discovery, cell systems, and clinical diagnostics.
