6 research outputs found
Preparation of Silicon–Carbon-Based Dots@Dopamine and Its Application in Intracellular Ag<sup>+</sup> Detection and Cell Imaging
A novel nanocomposite, silicon–carbon-based
dots@dopamine (Si-CDs@DA) was prepared using (3-aminopropyl) triethoxysilane,
glycerol, and dopamine as raw materials via a rapid microwave-assisted
irradiation. This type of Si-CDs@DA exhibited ultrabright fluorescence
emission (quantum yield of 12.4%) and could response to Ag<sup>+</sup> selectively and sensitively. Moreover, the obtained Si-CDs@DA can
be further applied in sensing intracellular Ag<sup>+</sup> and cell
imaging, because of its photostability, salt stability, and low cytotoxicity.
This study provides a simple and efficient approach for preparing
novel Ag<sup>+</sup> fluorescent probes, which could expand the application
of carbon nanomaterials in designing related biosensors
Stable and Reusable Electrochemical Biosensor for Poly(ADP-ribose) Polymerase and Its Inhibitor Based on Enzyme-Initiated Auto-PARylation
A stable and reusable electrochemical
biosensor for the label-free detection of polyÂ(ADP-ribose) polymerase
(PARP) is designed in this work. C-kit-1, a thiol-modified G-quadruplex
oligonucleotide, is first self-assembled on a gold electrode surface.
The G-quadruplex structure of c-kit-1 can specifically tether and
activate PARP, resulting in the generation of negatively charged polyÂ(ADP-ribose)
polymer (PAR). On the basis of electrostatic attraction, PAR facilitates
the surface accumulation of positively charged electrochemical signal
molecules. Through the characterization of electrochemical signal
molecules, the label-free quantification of PARP is simply implemented.
On the basis of the proposed method, selective quantification of PARP
can be achieved over the linear range from 0.01 to 1 U with a calculated
detection limit of 0.003U. Further studies also demonstrate the applicability
of the proposed method to biosamples revealing the broad potential
in practical applications. Furthermore, inhibitor of PARP has also
been detected with this biosensor. Meanwhile, benefited from self-assembly
on solid surface, this biosensor possesses two important features,
i.e., reusability and stability, which are desirable in related biosensors
Fluorescence Regulation of Poly(thymine)-Templated Copper Nanoparticles via an Enzyme-Triggered Reaction toward Sensitive and Selective Detection of Alkaline Phosphatase
The
activity of alkaline phosphatase (ALP) is a crucial index of
blood routine examinations, since the concentration of ALP is highly
associated with various human diseases. To address the demands of
clinical tests, efforts should be made to develop more approaches
that can sense ALP in real samples. Recently, we find that fluorescence
of polyÂ(30T)-templated copper nanoparticles (CuNPs) can be directly
and effectively quenched by pyrophosphate ion (PPi), providing new
perspective in designing sensitive biosensors based on DNA-templated
CuNPs. In addition, it has been confirmed that phosphate ion (Pi),
product of PPi hydrolysis, does not affect the intense fluorescence
of CuNPs. Since ALP can specifically hydrolyze PPi into Pi, fluorescence
of CuNPs is thus regulated by an ALP-triggered reaction, and a novel
ALP biosensor is successfully developed. As a result, ALP is sensitively
and selectively quantified with a wide linear range of 6.0 ×
10<sup>–2</sup> U/L to 6.0 × 10<sup>2</sup> U/L and a
low detection limit of 3.5 × 10<sup>–2</sup> U/L. Besides,
two typical inhibitors of ALP are evaluated by this analytical method,
and different inhibitory effects are indicated. More importantly,
by challenging this biosensor with real human serums, the obtained
results get a fine match with the data from clinical tests, and the
serum sample from a patient with liver disease is clearly distinguished,
suggesting promising applications of this biosensor in clinical diagnosis
Sequence and Structure Dual-Dependent Interaction between Small Molecules and DNA for the Detection of Residual Silver Ions in As-Prepared Silver Nanomaterials
Investigations
on interaction between small molecules and DNA are
the basis of designing advanced bioanalytical systems. We herein propose
a novel interaction between heterocyclic aromatic compounds (HACs)
and single-stranded DNA (ssDNA). Taking methylene blue (MB) as a typical
HAC, it is found that MB can interact with cytosine (C)-rich ssDNA
in an enthalpy-driven process. The interaction between MB and C-rich
ssDNA is sequence and structure dual-dependent: at least three consecutive
C and single-stranded structure are necessary, affecting the fluorescence
response of metal nanoparticles. With the exception of the single-stranded
structure, double-stranded, i-motif, and C–Ag–C mismatch
structures will remarkably impede the interaction with MB. UV–vis
absorption, fluorescent, and electrochemical curves demonstrate that
the conjugated system, electron transition, and electron transfer
of MB are remarkably affected by MB-C-rich ssDNA interaction. In particular,
the absorption peak of MB at 664 nm decreases, and a new peak at 538
nm emerges. Therefore, the interaction can be characterized by a colorimetric
and ratiometric signal. Relying on the inhibition of C–Ag–C
mismatch and the enhanced analytical performances of the ratiometic
signal, the MB-C-rich ssDNA interaction is further employed to quantify
silver ions (Ag<sup>+</sup>) selectively and sensitively. In addition,
since silver nanomaterials cannot introduce C–Ag–C mismatch,
the fabricated biosensor is able to sense residual Ag<sup>+</sup> in
silver nanoparticles and silver nanowires, which is of great value
in the precise and economical preparation of silver nanomaterials
Fluorescence Regulation of Copper Nanoclusters via DNA Template Manipulation toward Design of a High Signal-to-Noise Ratio Biosensor
Because
of bioaccumulation of food chain and disability of biodegradation,
concentration of toxic mercury ions (Hg<sup>2+</sup>) in the environment
dramatically varies from picomolar to micromolar, indicating the importance
of well-performed Hg<sup>2+</sup> analytical methods. Herein, reticular
DNA is constructed by introducing thymine (T)–Hg<sup>2+</sup>–T nodes in polyÂ(T) DNA, and copper nanoclusters (CuNCs) with
aggregate morphology are prepared using this reticular DNA as a template.
Intriguingly, the prepared CuNCs exhibit enhanced fluorescence. Meanwhile,
the reticular DNA reveals evident resistance to enzyme digestion,
further clarifying the fluorescence enhancement of CuNCs. Relying
on the dual function of DNA manipulation, a high signal-to-noise ratio
biosensor is designed. This analytical approach can quantify Hg<sup>2+</sup> in a very wide range (50 pM to 500 μM) with an ultralow
detection limit (16 pM). Besides, depending on the specific interaction
between Hg<sup>2+</sup> and reduced l-glutathione (GSH),
this biosensor is able to evaluate the inhibition of GSH toward Hg<sup>2+</sup>. In addition, pollution of Hg<sup>2+</sup> in three lakes
is tested using this method, and the obtained results are in accord
with those from inductively coupled plasma mass spectrometry. In general,
this work provides an alternative way to regulate the properties of
DNA-templated nanomaterials and indicates the applicability of this
way by fabricating an advanced biosensor
Aggregation of Individual Sensing Units for Signal Accumulation: Conversion of Liquid-Phase Colorimetric Assay into Enhanced Surface-Tethered Electrochemical Analysis
A novel
concept is proposed for converting liquid-phase colorimetric
assay into enhanced surface-tethered electrochemical analysis, which
is based on the analyte-induced formation of a network architecture
of metal nanoparticles (MNs). In a proof-of-concept trial, thymine-functionalized
silver nanoparticle (Ag-T) is designed as the sensing unit for Hg<sup>2+</sup> determination. Through a specific T-Hg<sup>2+</sup>-T coordination,
the validation system based on functionalized sensing units not only
can perform well in a colorimetric Hg<sup>2+</sup> assay, but also
can be developed into a more sensitive and stable electrochemical
Hg<sup>2+</sup> sensor. In electrochemical analysis, the simple principle
of analyte-induced aggregation of MNs can be used as a dual signal
amplification strategy for significantly improving the detection sensitivity.
More importantly, those numerous and diverse colorimetric assays that
rely on the target-induced aggregation of MNs can be augmented to
satisfy the ambitious demands of sensitive analysis by converting
them into electrochemical assays via this approach