A new cyano-substituted fluorescamine superior to its original form as a fluorescent probe for amino acid detection

FRET-based mesoporous organosilica nanoplatforms for in vitro and in vivo anticancer two-photon photodynamic therapy

We report the synthesis of multifunctional periodic mesoporous organosilica nanoparticles (PMO NPs) with substantial two-photon absorption properties and targeting capability for two-photon excitation fluorescence (TPEF) and photodynamic therapy (TPE-PDT). Prepared using an adapted sol-gel synthesis, the nanoplatforms integrated two silylated chromophores in their three-dimensional matrix to maximize non-radiative Förster resonance energy transfer from a high two-photon absorption fluorophore donor to a porphyrin derivative acceptor, leading to an enhanced generation of reactive oxygen species. Combinations of biodegradable and non-biodegradable bis(triethoxysilyl)alkoxysilanes were employed for the synthesis of the NPs, and the corresponding photophysical studies revealed high efficiency levels of FRET. Next, the cellular uptake and toxicities of pristine and functionalized NPs were evaluated on breast cancer cell lines upon TPEF and TPE-PDT. Notably, the use of TPE-PDT treatment led to high levels of phototoxicity on MCF-7 and MDA-MB-231 cancer cells with substantial effects when compared to one-photon excitation (OPE)-PDT treatment. Preliminary in vivo data on selective and biodegradable NPs showed a significant phototoxicity towards MDA-MB-231 on zebrafish xenograft embryos, making these advanced nanoplatforms promising candidates for future TPE-PDT-based cancer treatments.

Development of luminol-fluorescamine-PVP chemiluminescence system and its application to sensitive tyrosinase determination

Fluorescamine is a popular fluorescent probe. We report for the first time that luminol chemiluminescence (CL) can be enhanced by fluorescamine in the presence of PVP. The CL intensity of luminol-fluorescamine-PVP is about 26 times stronger than that of luminol. Both the removal of oxygen and the addition of superoxide dismutase (SOD) decrease CL intensity, thiourea and NaN₃ have little effect on CL intensities, indicating that O₂^•- is critical for CL. Interestingly, o-quinone generated from phenol by tyrosinase obviously inhibited the CL intensity. Inspired by such quenching effect on the luminol-fluorescamine-PVP CL system, a sensitive CL sensing for the determination of tyrosinase activity was developed. The method can detect tyrosinase in the range of 0.07-1.5 μg mL^-1 (0.19-4.02 U mL^-1) with the detection limit of 0.035 μg mL^-1 (0.094 U mL^-1). Moreover, this method exhibits satisfied recoveries for the spiked human serum samples.