Jinshui Liu

Enzyme‐Inspired Controlled Release of Cucurbit[7]uril Nanovalves by Using Magnetic Mesoporous Silica

The controlled release of drugs by biostimuli is highly desirable under physiological conditions for their potential use in advanced applications. The enzyme-inspired controlled release of cucurbituril nanovalves by using magnetic mesoporous silica nanoparticles (MSNs) in near-neutral aqueous solutions is reported for the first time. The encirclement of cucurbit[7]uril (CB[7]) onto the protonated 1,4-butanediamine stalks tethered to the external surfaces of superparamagnetic Fe(3) O(4) -embedded mesoporous silica particles leads to tight blocking of the nanopores. The supramolecular nanovalves are activated by the enzymatic decarboxylation products of lysine, cadaverine (in the protonated form), which has a high affinity for CB[7], so that the encapsulated guest molecules, calcein, in the nanopores are released into the bulk solution. The release of calcein can be controlled in small portions on command by alternating changes in enzymatic decarboxylation products and CB[7]. The amino acid derived polyamines have long been associated with cell growth and cancers. The guest molecules released from the delivery system of magnetic MSNs can act not only on sensing probes for levels of decarboxylases and polyamines, but also on efficacious drugs to specific tissues and cells for regulation of polyamine synthesis.

Preparation and Application of a Novel Composite Nanoparticle as a Protein Fluorescence Probe

ABSTRACT A novel composite nanoparticle has been prepared by an in situ polymerization method under ultrasonic irradiation. The nano‐CdS has been prepared, then the polymerization of acrylic acid (AA) was carried out by initiator potassium persulfate (KPS) under ultrasonic irradiation. The surface of the composite nanoparticles was covered with abundant carboxylic groups (–COOH). The nanoparticles are water‐soluble, stable and biocompatible. The fluorescence intensity of the composite nanoparticles is significantly increased in the presence of micro protein at pH 5.50. Based on this, a new fluorescence probe was developed for the determination of proteins including BSA, HSA, and human γ‐IgG. The fluorescence emission is measured at λem/λex = 580/400 nm. Under the optimum conditions, the response is linearly proportional to the concentration of proteins. The linear range is 0.1–40 µg mL−1 for BSA, 0.2–25 µg mL−1 for HSA and 0.1–15 µg mL−1 for human γ‐IgG. The method has been applied to the determination of the total protein in human serum samples collected from the hospital and the results are in good agreement with those reported by the hospital, which indicates that the method presented here is not only sensitive, simple, inexpensive but also reliable.

Convenient fluorescence detection of Cr(III) in aqueous solution based on the gold nanoparticle mediated release of the acridine orange probe

A simple and very sensitive method for detecting Cr3+ ions was developed. The method was based on fluorescence resonance energy transfer between acridine orange (AO) and gold nanoparticles (AuNPs), with AO acting as the donor and the AuNPs acting as acceptors. The method takes advantage of the high quenching efficiency of AuNPs and the large absorption band shift from 520 to 650 nm when AuNPs aggregate. The high quenching efficiency is caused by the non-covalent binding of AO to a AuNP surface through electrostatic interactions, forming an AO/AuNP system. Adding Cr3+ ions causes the intense fluorescence of the AO to be recovered because the Cr3+ ions induce the AuNPs to aggregate and the AO to be released from the AuNP surfaces. Under optimal conditions, the change in fluorescence intensity when Cr3+ ions were added was proportional to the Cr3+ concentration over the range of 0–12 μM. The detection limit was 0.02 μM. The system offers a new quantitative method for determining Cr3+ ions.

Fluorescence sensor for detecting protamines based on competitive interactions of polyacrylic acid modified with sodium 4-amino-1-naphthalenesulfonate with protamines and aminated graphene oxide

An easy-to-use fluorescent probe for detecting protamines was developed. Protamines are detected using the probe because of competitive interactions of polyacrylic acid modified with sodium 4-amino-1-naphthalenesulfonate (ANS-PAA) with protamines and aminated graphene oxide (GO-NH2). The ANS-PAA fluorescence was effectively quenched by the GO-NH2, the high quenching efficiency being caused by the ANS-PAA becoming non-covalently bound to the GO-NH2 surface through electrostatic interactions, forming a ANS-PAA/GO-NH2 complex. Adding protamines recovered the fluorescence of the ANS-PAA/GO-NH2 complex. This recovery was due to the positively charged protamines removing ANS-PAA from the GO-NH2 surfaces and forming ANS-PAA/protamine complexes. Displacement of GO-NH2 by protamines gave a high fluorescence recovery efficiency. Under optimal conditions, the fluorescence intensity when protamines were added was proportional to the protamine concentration over the range 0 to 6.0 μg mL−1. The detection limit was 0.4 μg mL−1. This approach offers a new quantitative method for determining protamines.

Preparation and Application of a Novel Fluorescent Nanoparticle as Aluminum Fluorescence Probe

Abstract A new type of fluorescent triphenylene nanoparticles, in the 30–40 nm size range have been prepared by reprecipitation method. These colloids show higher luminescent intensity than that in acetone solution with the same concentration. The fluorescence emission was measured at λ ex/λ em = 307/461 nm. In the optimum pH range of 7.2–8.3, at room temperature, enhancement of this emission can be accomplished by the addition of aluminum ion. The enhancement intensity of fluorescence was proportional to the concentration of aluminum in the range of 8.2–200 µg/L. Its detection limits are 0.15 µg/L. Based on this, a new quantitive method for aluminum assay presented. Large excesses of cations and anions were found to have no interference. The developed method was successfully applied to determine real samples.