ABSTRACT
Tungsten disulfide (WS2) nanosheets were discovered to possess intrinsic peroxidase-like activity and catalyze the peroxidase substrate 3,3',5,5'-tetramethylbenzidine (TMB) to produce a color reaction in the presence of H2O2. Based on this finding, a colorimetric method and a portable test kit for the visual detection of blood glucose have been developed by using glucose oxidase (GOx) and WS2 nanosheets-catalyzed reactions. The linear range for glucose was ranged from 5 to 300 µM (R(2)=0.999) with the detection limit of 2.9 µM. The portable test kit was successfully evaluated glucose levels in serum samples from normal persons and diabetes persons by the observable color change from pale yellow to yellow-green, blue-green.
Subject(s)
Biosensing Techniques/methods , Blood Glucose/analysis , Colorimetry/methods , Biosensing Techniques/instrumentation , Blood Chemical Analysis/methods , Diabetes Mellitus/blood , Glucose Oxidase , Humans , Hydrogen Peroxide , Metal Nanoparticles , Sepharose , Tungsten CompoundsABSTRACT
g-C3N4 was found to possess intrinsic peroxidase-like activity, and could catalytically oxidize 3,3',5,5'-tetramethylbenzidine (TMB) by H2O2 to produce a color reaction. Using g-C3N4 peroxidase-like catalytic activity and glucose oxidase (GOx), a colorimetric method for glucose detection in serum samples has been developed. The linear range for glucose was from 5 to 100 µM (R(2)=0.9987) and the limit of detection was as low as 1.0 µM. The proposed method was applied to detect glucose in serum samples by the naked eyes.
Subject(s)
Biomimetic Materials/chemistry , Biosensing Techniques/methods , Blood Glucose/analysis , Graphite/chemistry , Nitriles/chemistry , Peroxidase/chemistry , Colorimetry/methods , Humans , Hydrogen Peroxide/analysis , Limit of Detection , Oxidation-ReductionABSTRACT
A novel pH-sensitive controlled release system is proposed by using mussel-inspired polydopamine (PDA) coated mesoporous silica nanoparticles (MSNs) as nanocarriers. MSNs with a large pore diameter are synthesized by using 1,3,5-trimethylbenzene as a pore-expanding agent and are modified with a PDA coating by virtue of oxidative self-polymerization of dopamine in neutral pH. PDA coated MSNs are characterized by FTIR, TEM, N2 adsorption and XPS techniques. The PDA coating can work as pH-sensitive gatekeepers to control the release of drug molecules from MSNs in response to the pH-stimulus. Doxorubicin (DOX, an anticancer drug) can be released in the acid media and blocked in the neutral media.
Subject(s)
Delayed-Action Preparations/chemistry , Drug Carriers/chemistry , Indoles/chemistry , Nanoparticles/chemistry , Polymers/chemistry , Silicon Dioxide/chemistry , Animals , Antibiotics, Antineoplastic/chemistry , Bivalvia , Doxorubicin/chemistry , Hydrogen-Ion Concentration , PorosityABSTRACT
An amplified colorimetric detection of Hg(2+) is proposed by combining T-Hg(2+)-T base pairs and hybridization chain reaction (HCR). Two hairpins consisting of three-fourths and one-fourth of the horseradish peroxidase (HRP)-mimicking DNAzyme in inactive configuration are used as functional elements. In the presence of Hg(2+), one of the hairpins is opened by an assistant probe with the help of T-Hg(2+)-T base pairs and this triggers an autonomous cross-opening of the two hairpins using the strand displacement principle, resulting in the formation of DNA nanowires consisting of numerous reunited Q-quadruplex DNAzyme units. The resulting catalytically active hemin/G-quadruplex HRP-mimicking DNAzymes catalyze the oxidation of ABTS(2-) by H2O2 into a green-colored cationic radical ABTS(â¢+) for the colorimetric readout. This "turn-on" sensing system enables the high sensitive and selective detection of aqueous Hg(2+) with a detection limit of 9.7 pM.
Subject(s)
Biosensing Techniques , G-Quadruplexes , Ions/isolation & purification , Mercury/isolation & purification , Colorimetry , DNA, Catalytic/chemistry , Hydrogen Peroxide , Ions/chemistry , Limit of Detection , Mercury/chemistry , Nanowires/chemistryABSTRACT
A pH-responsive controlled release system is proposed using acid-decomposable layered double hydroxides (LDHs) as inorganic nanovalves by virtue of the electrostatic adsorption of LDH nanosheets on the surface of mesoporous silica nanoparticles (MSNs). Guest molecules (Ru(bpy)3Cl2 in this case) are loaded and encapsulated in a neutral environment. The dissolution of the LDH coatings in an acidic environment triggers the release of the guest molecules from the MSNs.
