Oxygen vacancies rich yttrium doped-Co3O4 nanosheets with peroxidase-like activity for sensitive rutin detection

Green synthesis of stable platinum nanoclusters with enhanced peroxidase-like activity for sensitive detection of glucose and glutathione

Appropriate addition of phosphate salt in food can improve the food quality and taste. However, extensive intake of phosphate salt may lead to some human diseases such as hyperphosphatemia and renal insufficiency. Thus, it is essential to establish a cost-effective, convenient, sensitive, and selective method for monitoring phosphate ion (Pi) to ensure food quality control. In this work, a Co-based metal-organic frameworks (Co-MOF) nanomaterial with dual functions (peroxidase-like activity and specific recognition) was designed for acting as a catalytic chromogenic platform for sensitive detection of Pi. The Co2+ nodes not only provide high enzyme-like activity to catalyze the 3,3′,5,5′--tetramethylbenzidine (TMB) substrate to blue oxTMB (652 nm) but also act as selective sites for Pi recognition. The use of cationic organic ligands (2-methylimidazole) and cationic metal ions (Co2+) endows the Co-MOF with a strong positive surface charge, which is beneficial to the capture of negative-charged Pi and the dramatically suppressed TMB oxidation. When Pi exists, it specifically adsorbs onto the Co-MOF through the Co-O-P bond and the strong electrostatic interaction, leading to the change of surface charge on Co-MOF. The peroxidase-like catalytic activity of Co-MOF is thus restrained, causing a different catalytic effect on TMB oxidation from that without Pi. Based on this principle, a colorimetric assay was established for rapid and sensitive detection of Pi. A good linear relationship was obtained between Pi concentration and the absorbance at 652 nm, with a linear range of 0.009–0.144 mg/L and a detection limit of 5.4 μg/L. The proposed assay was applied to the determination of Pi in actual food samples with recoveries of 92.2–108% and relative standard deviations (RSDs) of 2.7–7.3%, illustrating the promising practicality for actual samples analysis.

Facile preparation of Fe3O4 nanospheres/reduced graphene oxide nanocomposites with high peroxidase-like activity for sensitive and selective colorimetric detection of acetylcholine

Prussian blue nanoparticles as peroxidase mimetics for sensitive colorimetric detection of hydrogen peroxide and glucose

Until now, despite much progress in the study of metal-organic gels (MOGs), the modification of transition-metal containing MOGs with noble metal nanoparticles (NPs) is far from fully developed. Herein, iron-based MOGs nanosheet hybrids with gold NPs (AuNPs) immobilization were first synthesized by a facile in situ grown strategy at ambient conditions. It is found that the as-prepared AuNPs/MOGs (Fe) hybrids exhibited enhanced mimicking peroxidase-like activity, making them endowed with outstanding performance in chemiluminescence (CL) field in the presence of H2O2. The remarkable CL enhancement by AuNPs/MOGs (Fe) hybrids was attributed to the modification of AuNPs on MOGs (Fe) nanosheets, which could synergistically accelerate the CL reaction by speeding up the generation of OH•, O2•-, and 1O2. Accordingly, a sensitive CL detection of organophosphorus pesticides was successfully achieved by the AuNPs/MOGs (Fe) hybrids CL enhancing system in the range of 5-800 nM with a detection limit of 1 nM. We envision that this highly active and novel enzyme mimetic catalyst can be applicable to other extended AuNPs/MOGs (Fe) hybrid-based CL systems for sensitive detection of various analytes.

A novel sensor based on a silica gel–graphene composite for sensitive and selective detection of rutin.

Anovel colorimetric aptasensor has been developedfor highly sensitive tetracycline (TC) detection based on the peroxidase-like activity of Fe3O4@Cu nanoparticles and "sandwich" oligonucleotide hybridization. The Fe3O4@Cu nanoparticles with high peroxidase-like activity were successfully synthesized under mild conditions. Then, a "sandwich" oligonucleotide hybridization probe (a short amino-modified complementary sequence of a portion of the TC aptamer (cDNA1), TC aptamers, and a long complementary to 5' terminal TC aptamer sequence (cDNA2)) was created in 96-wells plates via DNA hybridization in the absence of TC from the detection system. The unique "sandwich" oligonucleotide hybridization probe adsorbed large numbers of Fe3O4@Cu nanozymes while further enhancing its peroxidase-like activity. Based on the 3,3',5,5'-tetramethylbenzidine (TMB)-hydrogen peroxide (H2O2) reporting system, the blue color of the solution decreased linearly with the increase ofTC concentration, ranging from 10-3 to 103μg/L with an ultralow limit of detection (LOD) of 0.91ng/L (2pM). Theproposed method was successfully applied to detect TC in spiked milk samples, with recoveries of 81.8 to 112%, demonstrating the excellent potential for highly sensitive TC detection in milk.

Anaminated Fe-Ni bimetallic metal-organic framework (Fe3Ni-MOF-NH2) with both peroxidase-like activity and fluorescence properties was developed. Fe3Ni-MOF-NH2 possessed the enhanced peroxidase-like activity through the enhanced electron transfer process and hydroxyl radical (·OH) generation. It was found that the amino group endowed the material with fluorescent property and the metal site Ni in Fe3Ni-MOF-NH2 could also enhance the fluorescence emission intensity (Ex = 345nm, Em = 452nm). Based on the dual excellent performance of Fe3Ni-MOF-NH2, a novel sensitive fluorescence detection strategy for H2O2 and glucose was designed and achieved. First, Fe3Ni-MOF-NH2 converted H2O2 to ·OH by exerting peroxidase-like activity, and ·OH converts catechol to o-benzoquinone. Then, the amino group in Fe3Ni-MOF-NH2 connected to o-benzoquinone, which resulted in its fluorescence quenching. The detection limit of H2O2 was as low as 5nM. Combined with glucose oxidase which can oxidize glucose and produce H2O2 the glucose could be indirectlydetermined with a detection limit of 40nM. The method was applied to the detection of low-level glucose in human urine samples with good recoveries and reproducibilities.

Rapid and sensitive multimode detection of Salmonella typhimurium based on the photothermal effect and peroxidase-like activity of MoS2@Au nanocomposite

In recent years, nanozyme-based sensing platforms have been attracted for their excellent performances in practical applications. Glypican-3 (GPC3) has been extensively regarded as a sensitive biomarker for hepatocellular carcinoma (HCC). In this work, the hemin-reduced oxide graphene-platinum@palladium nanoparticles (H-R-Pt@Pd NPs) with the peroxidase-like activity have been used to construct a facile colorimetric aptasensor for GPC3 detection. GPC3 aptamer (Apt) conjugated to the surface of H-R-Pt@Pd NPs serves as a signal probe, and GPC3 antibody (Ab) uses as a capture probe. In the presence of GPC3, it was recognized by the Ab and the Apt on the H-R-Pt@Pd NPs and initiated the formation of an H-R-Pt@Pd NPs-Apt/GPC3/Ab sandwich structure complex. Taking advantage of the excellent enzymatic catalytic properties, H-R-Pt@Pd NPs can oxidase colorless 3,3’,5,5’-tetramethylbenzidine (TMB) into blue oxTMB with the presence of H2O2, and the absorbance of the system at 652 nm changed consequently, which realize the sensitive colorimetric detection of GPC3. In addition, the catalytic mechanism of H-R-Pt@Pd NPs was confirmed by free radical experiments to be induced by hydroxyl radicals ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\cdot $ </tex-math></inline-formula> OH). Under optimal conditions, the aptasensor has a linear range of 10–300 ng/mL and a limit of detection (LOD) of 5.06 ng/mL. Furthermore, the aptasensor is employed to detect GPC3 in human serum samples with the recoveries of 105.94%–116.33% and relative standard deviations (RSDs) of 0.93%–3.08%. Overall, this assay possesses high selectivity and operability, and good sensitivity, indicating the potential for GPC3 detection in the field of clinical HCC diagnosis.

Metal-organic framework composite Mn/Fe-MOF@Pd with peroxidase-like activities for sensitive colorimetric detection of hydroquinone

Active site-tuned high peroxidase-like activity nanozyme for on-the-spot detection of saliva total antioxidant capacity using smartphone devices

Facile synthesis of IrO2/rGO nanocomposites with high peroxidase-like activity for sensitive colorimetric detection of low weight biothiols

A novel four-modal nano-sensor based on two-dimensional Mxenes and fully connected artificial neural networks for the highly sensitive and rapid detection of ochratoxin A

Peroxidase-like phosphate hydrate nanosheets bio-synthesized by a marine Shewanella algae strain for highly sensitive dopamine detection