In
this work, the inherent Fenton-like activity of Mn3O4 nanoparticles (Mn3O4 NPs) was
explored to catalyze the polymerization of dopamine to blue-emitting
polydopamine dots (PDA-dots), which can be used for selective detection
of dopamine (DA) and tyrosinase (TYR). It was demonstrated that Mn3O4 NPs sparklingly oxidized DA to its quinone derivatives
at the same time decomposing hydrogen peroxide to hydroxyl radicals
that controlled the polymerization to PDA-dots. Interestingly, Mn3O4 NPs retained high activity to produce PDA-dots
after repeated use of five cycles. It was found that with the polymerization
of DA, the FL intensity of the produced PDA-dots changes in a dose-dependent
on dopamine concentration. Therefore, under the optimum conditions,
a turn-on fluorometric detection was thereby established to detect
dopamine, showing a linear range of dopamine concentration from 0.050
μM to 300 μM. The Mn3O4 NPs-assisted
preparation of fluorescent PDA-dots was further exploited to detect
TYR by using tyramine as its model substrate. This simple strategy
showed a limit of detection of 0.0048 U/mL toward TYR and displayed
a linear response in the concentration range from 0.021 to 13.43 U/mL.
Importantly, this study not only provides insight into how to quickly
synthesize polydopamine dots that would be explored in biomedical
applications but also establish a method to obtain highly discriminative
and sensitive detection of dopamine and tyrosinase.
This work demonstrates a simple and versatile deep eutectic solvent (DES)-assisted synthesis of bullet-shaped cerium−zinc oxide (Ce− ZnO) and sheet-like cerium−zinc hydroxide nitrate (Ce−Zn 5 (OH) 8 (NO 3 ) 2 • 2H 2 O). DES could serve not only as a green solvent but also as a superior template to produce these two different hierarchically shaped materials. Interestingly, Ce−ZnO shows catalytic activity toward polymerization of dopamine to initially pink color quinone derivatives with the visible light absorption at 475 nm and finally to blue-emitting polydopamine with highest fluorescence intensity at 480 nm. The catalytic activity of Ce−ZnO can be selectively inhibited by pyrophosphate ions (PPi), which leads to a decrease in the absorbance intensity or fluorescence emission. PPi detection strategies were established, and the linearity was achieved from 0.5 to 100 μM with a low detection limit of 0.05 μM for the fluorometric detection, while the linear detection was 0.5−150 μM and the low detection limit was 0.19 μM for colorimetric detection. This work offers a new opportunity to produce Ce−ZnO and Ce−Zn 5 (OH) 8 (NO 3 ) 2 •2H 2 O using an inexpensive and eco-friendly solvent, and provides a useful way of detecting PPi. Hence, from these findings, the proposed synthesis strategy is expected to serve as a novel green strategy for preparing hierarchically shaped materials.
Construction of protein-inorganic hybrid materials with hierarchical nanostructures is critical for the creation of advanced multi-functional materials. We herein for the first time report the synthesis of protein-manganese phosphate hybrid nanomaterials by environmentally amiable biomineralization approach. We have demonstrated that collagen provides an excellent biotemplate to modulate the morphology of the hybrid materials, leading to exquisite nanoflowers with branched petals. In this timedependent biomineralization process, collagen played an essential role in the production of proteinmanganese phosphate hybrid materials by inducing the nucleation of manganese phosphates to form a scaffold as well as serving as a glue to hold the petals together. The as-prepared CL-Mn 3 (PO 4 ) 2 nanoflowers exhibited good catalytic activity towards water oxidation. The unique (Gly-X-Y) n amino acid sequences and triple helix structure may provide extraordinary capability for collagen to create hybrid nanomaterials via collagen-templated biomineralization. The single-size and high purity may endow recombinant collagen as a powerful strategy to establish superior biotemplates. This facile and green approach to produce collagen-manganese phosphate hybrid nanoflowers greatly advances our capability to construct manganese phosphates-based functional materials.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.