nanomaterials and their application in the biomedicine. [7] Indeed, over the past decades, formation of protein corona onto surfaces of NPs has attracted great attentions in the nanotechnology and biology community, and impressive progress has been achieved. [8,9] Nevertheless, a quantitative analysis on the formation process of the protein corona is very difficult and complicated, owing to the highly dynamic NP-protein interaction process and too many influencing factors.Among various types of nanomaterials, ultrasmall NPs with sizes smaller than 10 nm (i.e., quantum dots, [10] metal nanoclusters, [11] and carbon dots) [12] show unique properties and great potential in molecular imaging for disease diagnosis and cancer treatment. Particularly, compared with large NPs, these ultrasmall NPs can more readily escape from macrophages, pass biological barriers, show longer blood circulation times, and be easily degraded or excreted in the living systems. [13,14] Thus, these ultrasmall NPs have been widely employed in various biomedical applications. However, a deep and comprehensive understanding of their biological behavior, i.e., NP-protein interactions, remains largely unclear yet mainly due to the lack of appropriate in situ characterization tools for these ultrasmall NPs. While researchers have developed several techniques such as fluorescence correlation spectroscopy, [15] dynamic light scattering, [16] synchrotron radiation-based techniques, [17] and nuclear magnetic resonance spectroscopy [18] enabling quantitative analysis of protein corona, it still requires the development of new approaches to monitor the protein-NP interactions in a highly sensitive and quantitative manner owing to the diversity of nanomaterials and complexity of biological systems. [19] Fluorescence resonance energy transfer (FRET) is the process of nonradiative transmission of excitation energy from an excited state donor to a ground state acceptor, resulting from the dipole-dipole interactions. [20] The efficiency of this energy transfer process is inversely proportional to the sixth power of the distance between donor and acceptor, making FRET extremely sensitive to small changes in distance. Therefore, FRET has been widely exploited as a "spectroscopic ruler" in many biological and biophysical researches. For example, FRET can be employed for monitoring conformational changes of biomolecules, [21] developing highly sensitive fluorescence A fundamental understanding of nanoparticle-protein corona and its interactions with biological systems is essential for future application of engineered nanomaterials. In this work, fluorescence resonance energy transfer (FRET) is employed for studying the protein adsorption behavior of nanoparticles. The adsorption of human serum albumin (HSA) onto the surface of InP@ZnS quantum dots (QDs) with different chirality (dand l-penicillamine) shows strong discernible differences in the binding behaviors including affinity and adsorption orientation that are obtained upon quantitative analysis of FRET data...

A novel fluorescence turn-on strategy for glucose sensing is demonstrated. The fluorescence of a perylene probe could be quenched by the silver nanoparticles (Ag NPs). The Ag NPs could be etched by H2O2 generated from the enzymatic oxidation of glucose. And efficient probe fluorescence recovery was detected.

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