ascorbate-2-phosphate and titanium-dioxide

In this Letter, on the basis of the CdS quantum dots functionalized TiO2 nanotubes electrode, we proposed a simultaneous photoelectrochemical (PEC) immunoassay of dual cardiac markers using specific enzyme tags of alkaline phosphatase (ALP) and acetylcholine esterase (AChE). ALP and AChE were integrated into the PEC system through the sandwich immunobinding and could specifically catalyze the hydrolysis of ascorbic acid 2-phosphate (AAP) or the acetylthiocholine (ATC) to in situ generate ascorbic acid (AA) or thiocholine (TC) for sacrificial electron donating. These two enzymes were thus used to differentiate the signals of two cardiac targets in connection with the sandwich immunorecognition and PEC responses to the corresponding electron donors. This strategy demonstrates a proof of principle for the successful integration of dual enzyme tags with PEC immunoassay that can potentially provide a general format for multiplexed PEC bioanalysis.

Topics: Acetylcholinesterase; Acetylthiocholine; Alkaline Phosphatase; Antibodies, Immobilized; Ascorbic Acid; C-Reactive Protein; Chemistry Techniques, Analytical; Electrochemical Techniques; Electrodes; Humans; Immunoassay; Nanotubes; Quantum Dots; Titanium; Troponin I

Zinc oxide (ZnO) appears as a promising preservative for pharmaceutical or cosmetic formulations. The other ingredients of the formulations may have specific interactions with ZnO that alter its antimicrobial properties. The influence of common formulation excipients on the antimicrobial efficacy of ZnO has been investigated in simple model systems and in typical topical products containing a complex formulation. A wide variety of formulation excipients have been investigated for their interactions with ZnO: antioxidants, chelating agents, electrolytes, titanium dioxide pigment. The antimicrobial activity of ZnO against Escherichia coli was partially inhibited by NaCl and MgSO4 salts. A synergistic influence of uncoated titanium dioxide has been observed. The interference effects of antioxidants and chelating agents were quite specific. The interactions of these substances with ZnO particles and with the soluble species released by ZnO were discussed so as to reach scientific guidelines for the choice of the ingredients. The preservative efficacy of ZnO was assessed by challenge testing in three different formulations: an oil-in-water emulsion; a water-in-oil emulsion and a dry powder. The addition of ZnO in complex formulations significantly improved the microbiological quality of the products, in spite of the presence of other ingredients that modulate the antimicrobial activity.

Topics: Administration, Topical; Anti-Infective Agents; Antioxidants; Ascorbic Acid; Aspergillus; Butylated Hydroxytoluene; Candida albicans; Chelating Agents; Edetic Acid; Escherichia coli; Excipients; Magnesium Sulfate; Preservatives, Pharmaceutical; Pseudomonas aeruginosa; Sodium Chloride; Staphylococcus aureus; Titanium; Zinc Oxide