Dimethyl-2,5-bis­[4-(methoxyphenyl)­amino] terephthalate (DBMPT) exhibits aggregation-induced enhancement of emission with Tween 40 and formation of nanorods with strong orange fluorescence. These nanorods disrupt fibrils of human serum albumin and lead to partial refolding of the protein, as monitored by circular dichroism and thioflavin T (ThT) fluorescence. The resultant milieu emits white light, the mechanism of which is explored in this study. It is established that direct excitation of the acceptor plays a significant role, even though Förster resonance energy transfer (FRET) is found to be operative to some extent. A decrease in the fluorescence intensity and lifetime of ThT with progressive addition of DBMPT, which is often used as the sole indicator of FRET, is ascribed to the disruption of the fibrils by the nanorods.

Water soluble CdSe nanotetrapods are prepared by ligand exchange from organic‐soluble ones. In order to achieve this, oleic acid, which is the capping agent for as prepared water‐insoluble nanotetrapods, is exchanged with mercaptopropanoic acid (MPA). Shape and size of nanotetrapods are conserved upon ligand exchange. Ground state bleach recovery dynamics remain the same as well. However, they are completely non‐emissive. These water‐soluble nanotetrapods disrupt the secondary structure of Human Serum Albumin (HSA) and consequently, release warfarin bound to the protein.

Fluorescence correlation spectroscopy and time-dependent fluorescence Stokes shift have been employed to elucidate dynamics in different time scales, ranging from picoseconds to nanoseconds, for human serum albumin, in its native and cationized forms as well as in the self-assembled complex of the cationized protein with the polymer surfactant (PS) glycolic acid ethoxylate lauryl ether. The effect of crowding in this complex, especially in the waterless condition, is of prime importance in this context. Excellent correlation of the dynamics with the structures, obtained by circular dichroism and Fourier transform infrared spectroscopy, has been observed. Slow solvation, associated classically with biological water, has been observed in these systems, even in the waterless condition. This apparently intriguing observation has been rationalized by the relaxation of segments of the protein and the PS in the microenvironment of the fluorescent probe.

Insights into blinking and photoactivation of aqueous copper indium sulfide (CIS) quantum dots have been obtained using fluorescence correlation spectroscopy (FCS) and fluorescence lifetime correlation spectroscopy (FLCS). An unusual excitation wavelength-dependence of photoactivation/photocorrosion is manifested in an increase in the initial correlation amplitude G(0) for λex = 532 nm, but a decrease for λex = 405 nm. This has been rationalized in terms of different contributions from surface-assisted recombination in the two cases. Blinking times obtained from the autocorrelation functions (ACFs) of the 100–200 ns lifetime component (core Cu-mediated recombination) are almost unaffected by shelling, but those from the ACF for the 10–30 ns lifetime (surface states) increase significantly. Absence of cross-correlation between the two recombinative states of bare CIS QDs and the emergence of an anticorrelation with the introduction of the ZnS shell are observed, indicating the diffusive nature of the two states for CIS-ZnS. The diffusion is inhibited in bare CIS QDs due to the preponderance of surface states.

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