Detection of cholesterol
and uric acid biomarkers is of great importance for clinical diagnosis
of several serious diseases correlated with their variations in human
blood serum. In this study, a new kind of well selective and highly
sensitive ratiometric fluorescent probe for cholesterol and uric acid
determination in human blood serum was innovatively developed on the
basis of the inner filter effect (IFE) process of nitrogen, cobalt
co-doped carbon dots (N,Co-CDs) with 2,3-diaminophenazine (DAP). DAP
was the oxidative product during the oxidation reaction between
o
-phenylenediamine and H
2
O
2
. Fluorescent
magnetic N,Co-CDs possessing blue emission and magnetic property were
prepared through a facile one-pot hydrothermal strategy by using citric
acid, diethylenetriamine, and cobalt(II) chloride hexahydrate as precursors.
N,Co-CDs exhibited good ferromagnetic property and excellent optical
properties even in extremely harsh environmental conditions, implying
the huge potential applications of such N,Co-CDs in biological areas.
On the basis of the IFE process between N,Co-CDs and DAP, N,Co-CDs
were applied to establish ratiometric fluorescent probes for the indirect
detection of cholesterol and uric acid that participated in enzyme-catalyzed
H
2
O
2
-generation reactions. The established IFE-based
fluorescent probes exhibited relatively low detection limits of 3.6
nM for cholesterol and 3.4 nM for uric acid, respectively. The fluorescent
probe was successfully utilized for the determination of cholesterol
and uric acid in human blood serum with satisfying results, which
provided an informed perspective on the applications of such doped
CDs to explore the specific and sensitive nanoprobe in disease diagnoses
and clinical therapy.
The exceptional nature of WO3−x dots has inspired widespread interest, but it is still a significant challenge to synthesize high‐quality WO3−x dots without using unstable reactants, expensive equipment, and complex synthetic processes. Herein, the synthesis of ligand‐free WO3−x dots is reported that are highly dispersible and rich in oxygen vacancies by a simple but straightforward exfoliation of bulk WS2 and a mild follow‐up chemical conversion. Surprisingly, the WO3−x dots emerged as co‐reactants for the electrochemiluminescence (ECL) of Ru(bpy)32+ with a comparable ECL efficiency to the well‐known Ru(bpy)32+/tripropylamine (TPrA) system. Moreover, compared to TPrA, whose toxicity remains a critical issue of concern, the WO3−x dots were ca. 300‐fold less toxic. The potency of WO3−x dots was further explored in the detection of circulating tumor cells (CTCs) with the most competitive limit of detection so far.
The development of electrochemiluminescent
(ECL) emitters with
both intense ECL and excellent film-forming properties is highly desirable
for biosensing applications. Herein, a facile one-pot preparation
strategy was proposed for the synthesis of a self-enhanced ECL emitter
by co-doping Ru(bpy)3
2+ and (diethylaminomethyl)triethoxysilane
(DEAMTES) into an in situ-produced silica nanohybrid (DEAMTES@RuSiO2). DEAMTES@RuSiO2 not only possessed improved ECL
properties but also exhibited outstanding film-forming ability, which
are both critical for the construction of ECL biosensors. By coupling
branched catalytic hairpin assembly with efficient signal amplification
peculiarity, a label-free ECL biosensor was further constructed for
the convenient and highly sensitive detection of miRNA-21. The as-fabricated
ECL biosensor displayed a detection limit of 8.19 fM, much lower than
those in previous reports for miRNA-21 and showed superior reliability
for detecting miRNA-21-spiked human serum sample, demonstrating its
potential for applications in miRNA-associated fundamental research
and clinical diagnosis.
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