Colorimetric Detection of Iodine Ion Based on Its Inhibition Effect on Peroxidase-Like Activity of Platinum Nanoparticles / 分析化学

As an important inorganic element, iodine not only plays an important role in human growth and metabolism, but also has an irreplaceable role in the chemical engineering, medicine, food and other fields.Thus the detection of iodine ion is of important significance.In this work, colorimetric recognition and sensing of iodine ion with high sensitivity was proposed based on target induced shielding of the peroxidase-like activity of bare platinum nanoparticles ( PtNPs ).This assay exhibited simplicity and cost-effectiveness.The recognition of iodine ion by bare PtNPs could be fulfilled in a few seconds and the assay could be accomplished within 10 min.The detection range for iodine ion was 20 nmol/L-5.0 μmol/L and the detection limit was 8 nmol/L ( S/N = 3 ).Furthermore, the new assay system did not require surface modification of nanoparticles, nor complex organic synthesis.This assay was successfully applied to detection of iodine concentration in real salt and water samples, exhibiting promising application prospects.

Antioxidants effects of Platinum Nanoparticles: A Potential Alternative Treatment to Lung Diseases.

Imbalance oxidative status occurs when oxidative stress is higher in the body due to the production of reactive oxygen species. Thus, antioxidants are needed to counteract the production of free radicals. Reoccurrence of oxidative stress in the lung cells will eventually lead to inflammation and edema. This will result to a severe prognosis of lung diseases. Our interest is to populate certain mechanisms that can be activated during this process by reversing the oxidative stress status. Platinum nanoparticles (PtNPs) have been suggested as one of the powerful antioxidants that can quench free radicals. The mechanistic pathway may involve Protein Kinase C, which correlates well with the expression of the Epithelial Sodium Channel (ENaC). ENaC plays an important role in sodium uptake thus stimulate lung liquid clearance. The failure of lung clearance will interrupt gaseous exchange thus eventually lead to death. This review will discuss on the antioxidant properties of PtNPs as well as the underlying mechanism of PKC and ENaC in maintaining the oxidative status in the lung cells.

Characterization and bacterial anti-adherent effect on modified PMMA denture acrylic resin containing platinum nanoparticles

PURPOSE: This study characterized the synthesis of a modified PMMA (Polymethyl methacrylate) denture acrylic loading platinum nanoparticles (PtN) and assessed its bacterial inhibitory efficacy to produce novel antimicrobial denture base material. MATERIALS AND METHODS: Polymerized PMMA denture acrylic disc (20 mm x 2 mm) specimens containing 0 (control), 10, 50, 100 and 200 mg/L of PtN were fabricated respectively. The obtained platinum-PMMA nanocomposite (PtNC) was characterized by TEM (transmission electron microscopy), SEM/EDX (scanning electron microscope/energy dispersive X-ray spectroscopy), thermogravimetric and atomic absorption spectrophotometer analysis. In antimicrobial assay, specimens were placed on the cell culture plate, and 100 microL of microbial suspensions of S. mutans (Streptococcus mutans) and S. sobrinus (Streptococcus sobrinus) were inoculated then incubated at 37degrees C for 24 hours. The bacterial attachment was tested by FACS (fluorescence-activated cell sorting) analysis after staining with fluorescent probe. RESULTS: PtN were successfully loaded and uniformly immobilized into PMMA denture acrylic with a proper thermal stability and similar surface morphology as compared to control. PtNC expressed significant bacterial anti-adherent effect rather than bactericidal effect above 50 mg/L PtN loaded when compared to pristine PMMA (P=.01) with no or extremely small amounts of Pt ion eluted. CONCLUSION: This is the first report on the synthesis and its antibacterial activity of Pt-PMMA nanocomposite. PMMA denture acrylic loading PtN could be a possible intrinsic antimicrobial denture material with proper mechanical characteristics, meeting those specified for denture bases. For clinical application, future studies including biocompatibility, color stability and warranting the long-term effect were still required.

Platinum nanoparticles reduce ovariectomy-induced bone loss by decreasing osteoclastogenesis

Platinum nanoparticles (PtNP) exhibit remarkable antioxidant activity. There is growing evidence concerning a positive relationship between oxidative stress and bone loss, suggesting that PtNP could protect against bone loss by modulating oxidative stress. Intragastric administration of PtNP reduced ovariectomy (OVX)-induced bone loss with a decreased level of activity and number of osteoclast (OC) in vivo. PtNP inhibited OC formation by impairing the receptor activator of nuclear factor-kappaB ligand (RANKL) signaling. This impairment was due to a decreased activation of nuclear factor-kappaB and a reduced level of nuclear factor in activated T-cells, cytoplasmic 1 (NFAT2). PtNP lowered RANKL-induced long lasting reactive oxygen species as well as intracellular concentrations of Ca2+ oscillation. Our data clearly highlight the potential of PtNP for the amelioration of bone loss after estrogen deficiency by attenuated OC formation.

Amperometric L-lactate Biosensor Based on Sol-Gel Film and Multi-walled Carbon Nanotubes/Platinum Nanoparticles Enhancement / 分析化学

An electrochemical L-lactate biosensor was fabricated by combining Platinum nanoparticles (Pt-nano) with multi-walled carbon nanotubes(MWCNTs).L-lactate oxidase(LOD) was immobilized on the surface of the glassy carbon electrode (GCE) modified with MWCNTs and Pt-nano.The surface of resulting LOD/MWCNTs/Pt-nano electrode was covered by a thin layer of sol-gel to avoid the loss of LOD and to improve the anti-interference ability.The cyclic voltammetric results indicated that MWCNTs/Pt-nano catalyst displayed a higher performance than MWCNTs.Under the optimized conditions, i.e., applied potential of 0.5 V, pH 6.4, 25 ℃, the proposed biosensor's determination range was 0.2-2.0 mmol/L, response time was within 5 s, and the sensitivity was 6.36 (A/(mmol/L).It still kept 90% activity after 4 weeks.The fabricated biosensor had practically good selectivity against interferences.The results for whole blood samples analyzed by the present biosensor showed a good agreement with those analyzed by spectrophotometric method.