5 research outputs found
From O<sub>2</sub><sup>–</sup>‑Initiated SO<sub>2</sub> Oxidation to Sulfate Formation in the Gas Phase
We
have investigated the chemical fate of O<sub>2</sub>SOO<sup>–</sup>, the immediate product of the reaction between sulfur
dioxide (SO<sub>2</sub>) and the superoxide ion (O<sub>2</sub><sup>–</sup>), by reactions with nitrogen oxides (NO and NO<sub>2</sub>) using high-level theoretical calculations. Both reactions
with NO and NO<sub>2</sub> lead to exergonic formation of adducts,
which subsequently overcome low energy barriers to form SO<sub>3</sub> + NO<sub>3</sub><sup>–</sup> and SO<sub>4</sub><sup>–</sup> + NO, with rate constants of 6.9 × 10<sup>–10</sup> and
6.3 × 10<sup>–10</sup> cm<sup>3</sup> molecule<sup>–1</sup> s<sup>–1</sup>, respectively. Reactions with water are ∼15–23
times slower than corresponding naked reactions at ambient conditions,
hence not slow enough to be prevented at these conditions. The studied
reactions not only are useful for understanding ionic SO<sub>2</sub> oxidation in the atmosphere and in chamber experiments but also
provide a new mechanism for the gas-phase formation of sulfate from
an ion-induced mechanism. These reactions may enhance our understanding
of the early stages of secondary aerosol formation
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
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
A Liquid–Liquid Interfacial Strategy for Construction of Electroactive Chiral Covalent–Organic Frameworks with the Aim to Enlarge the Testing Scope of Chiral Electroanalysis
Although
electroactive chiral covalent–organic
frameworks
(CCOFs) are considered an ideal platform for chiral electroanalysis,
they are rarely reported due to the difficult selection of suitable
precursors. Here, a facile strategy of liquid–liquid interfacial
polymerization was carried out to synthesize the target electroactive
CCOFs Ph-Py+-(S,S)-DPEA·PF6– and Ph-Py+-(R,R)-DPEA·PF6–.
That is, a trivalent Zincke salt (4,4′,4″-(benzene-1,3,5-triyl)tris(1-(2,4-dinitrophenyl)pyridin-1-ium))
trichloride (Ph-Py+-NO2) and enantiopure 1,2-diphenylethylenediamine
(DPEA) were dissolved in water and chloroform, respectively. The Zincke
reaction occurs at the interface, resulting in uniform porosity. As
expected, the cyclic voltammetry and differential pulse voltammetry
measurements showed that the tripyridinium units of the CCOFs afforded
obvious electrochemical responses. When Ph-Py+-(S,S)-DPEA·PF6– was modified onto the surface of a glassy carbon electrode as a
chiral sensor, the molecules, which included tryptophan, aspartic
acid, serine, tyrosine, glutamic acid, mandelic acid, and malic acid,
were enantioselectively recognized in the response of the peak current.
Very importantly, the discriminative electrochemical signals were
derived from Ph-Py+-(S,S)-DPEA·PF6–. The best peak current
ratios between l- and d-enantiomers were in the
range of 1.31–2.68. Besides, a good linear relationship between
peak currents and enantiomeric excess (ee) values was established,
which was successfully harnessed to determine the ee values for unknown
samples. In a word, the current work provides new insight and potential
of electroactive CCOFs for enantioselective sensing in a broad range
Postsynthetic Modification Strategy for Constructing Electrochemiluminescence-Active Chiral Covalent Organic Frameworks Performing Efficient Enantioselective Sensing
Electrochemiluminescence (ECL), integrating the characteristics
of electrochemistry and fluorescence, has the advantages of high sensitivity
and low background. However, only a few studies have been reported
for enantioselective sensing based on the ECL-active platform because
of the huge challenges in constructing tunable chiral ECL luminophores.
Here, we developed a facile strategy to design and prepare ECL-active
chiral covalent organic frameworks (COFs) Ph-triPy+-(R)-Ru(II) for enantioselective sensing. In such an artificial
structure, the ionic skeleton of COFs was beneficial to the electron
transfer on the working electrode surface and the chiral Ru-ligand
was used as the chiral ECL-active luminophore. It was found that Ph-triPy+-(R)-Ru(II) coupled with sodium persulfate
(Na2S2O8) as the coreactant exhibited
obvious ECL signals. More importantly, a clear difference toward l- and d-enantiomers was observed in the response of
the ECL intensity, resulting in a uniform recognition law. That is,
for amino alcohols, d-enantiomers (1 mM) measured by Ph-triPy+-(R)-Ru(II) showed a higher ECL intensity
compared with l-enantiomers. Differently, amino acids (1
mM) gave an inverse recognition phenomenon. The ECL intensity ratios
between l- and d-enantiomers (1 mM) are in the range
of 1.25–1.94 for serine, aspartic acid, glutamic acid, valine,
leucine, leucinol, and valinol. What is more interesting is that the
ECL intensity was closely related to the concentration of l-amino alcohols and d-amino acids, whereas their inverse
configurations remained unchanged. In a word, the present concept
demonstrates a feasible direction toward chiral ECL-active COFs and
their potential for efficient enantioselective sensing