Ultra-small and biocompatible platinum nanoclusters with peroxidase-like activity for facile glucose detection in real samples

Polyethyleneimine-Stabilized Platinum Nanoparticles as Peroxidase Mimic for Colorimetric Detection of Glucose

Colorimetric detection of glucose using enzyme-mimic nanoparticles (NPs) has been drawing great attention. However, many NPs lack good stability in solution, which results in reduced color change of substrates in colorimetric detection. Liner soluble macromolecules with high cationic density may be suitable candidates for the stabilization of NPs. Herein, we prepared polyethyleneimine-stabilized platinum NPs (Pt n -PEI NPs) for colorimetric detection of glucose. The platinum NPs (Pt NPs) used in this system had small size (from 3.21 to 3.70 nm) and narrow size distribution. Pt50-PEI NPs had high stability within one week with a hydrodynamic size of ∼25 nm and slightly positive zeta potential. Pt50-PEI NPs-catalyzed oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of H2O2, generating blue oxidized TMB (oxTMB), which indicated the peroxidase-like property of Pt50-PEI NPs. The optimal condition for this reaction was pH = 4.0 at 30 °C. More importantly, Pt50-PEI NPs were successfully used to detect glucose concentration by a colorimetric method with high selectivity. The established method had a linear concentration range from 10 to 5000 μM with a detection limit of 4.2 μM. For example, the concentration of glucose in saliva was tested to be 0.15 mM using our method. The high stability of Pt50-PEI NPs enhanced the high accessibility of the active center of Pt NPs for substrates and consequent excellent catalytic property. This established method has great potential to be used in various applications for glucose detection in the future.

Ginkgo biloba leaf polysaccharide stabilized palladium nanoparticles with enhanced peroxidase-like property for the colorimetric detection of glucose

Sensitive glucose detection based on nanoparticles is good for the prevention of illness in our bodies. However, many nanoparticles lack stability and biocompatibility, which restrict their sensitivity to glucose detection. Herein, stable and biocompatible Ginkgo biloba leaf polysaccharide (GBLP) stabilized palladium nanoparticles (Pd n -GBLP NPs) were prepared through a green method where GBLP was used as a reducing and stabilizing agent. The results of Pd n -GBLP NPs characterized by UV-visible spectroscopy (UV-Vis), Fourier transform infrared (FTIR) spectroscopy, transmission electron microscopy (TEM) and X-ray photoelectron spectra (XPS) confirmed the successful preparation of Pd n -GBLP NPs. TEM results indicated that the sizes of Pd NPs inside of Pd n -GBLP NPs (n = 41, 68, 91 and 137) were 7.61, 9.62, 11.10 and 13.13 nm, respectively. XPS confirmed the successful reduction of PdCl4 2- into Pd (0). Dynamic light scattering (DLS) results demonstrated the long-term stability of Pd n -GBLP NPs in different buffer solutions. Furthermore, Pd91-GBLP NPs were highly biocompatible after incubation (500 μg mL-1) with HeLa cells for 24 h. More importantly, Pd91-GBLP NPs had peroxidase-like properties and followed a ping-pong mechanism. The catalytic oxidation of substrate 3,3',5,5'-tetramethylbenzidine (TMB) into blue oxidized TMB (oxTMB) by Pd91-GBLP NPs was used to detect the glucose concentration. This colorimetric method had high selectivity, wide linear range from 2.5 to 700 μM and a low detection limit of 1 μM. This method also showed good accuracy for the detection of glucose concentrations in blood. The established method has great potential in biomedical detection in the future.