Zusammenfassung
A nanoengineered interface fabricated by self assembly enables the online determination of vitamin B12 via a simple luminescence readout in serum without any pretreatment. The interplay of Tm3+-doped NaYF4 nanoparticles (UCNPs) and a gold nanotriangle array prepared by nano sphere lithography on a glass slide is responsible for an efficient NIR to UV upconversion. Hot spots of the gold assembly ...
Zusammenfassung
A nanoengineered interface fabricated by self assembly enables the online determination of vitamin B12 via a simple luminescence readout in serum without any pretreatment. The interplay of Tm3+-doped NaYF4 nanoparticles (UCNPs) and a gold nanotriangle array prepared by nano sphere lithography on a glass slide is responsible for an efficient NIR to UV upconversion. Hot spots of the gold assembly generate local electromagnetic-field enhancement, favoring the four-photon upconversion process at the low-power excitation of approximately 13 W.cm(-2). An improvement by about 6 times of the intensity for the emission peaking at 345 nm is achieved. The nanoengineered interface has been applied in a proof-of-concept sensor for vitamin B12 in serum, which is known as a marker for the risk of cancer; Alzheimer disease; or, during pregnancy, neurological abnormalities in newborn babies. Vitamin B12 can be detected in serum down to 3.0 nmol.L-1 by a simple intensity-based optical readout, consuming only 200 mu L of a sample, which qualifies as easy miniaturization for point-of-care diagnostics. Additionally, this label-free approach can be used for long-term monitoring because of the high photostability of the upconversion nanoparticles.
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