Portable, stable, and sensitive assay to detect phosphate in water with gold nanoparticles (AuNPs) and dextran tablet

Abstract

A novel and highly sensitive tablet-based colorimetric sensor is developed for the detection of phosphate (Pi) in drinking and surface water using mercaptoacetic acid-gold nanoparticles (MA-AuNPs). Characterization of AuNPs and...

Gold Tablets: Gold Nanoparticles Encapsulated into Dextran Tablets and Their pH-Responsive Behavior as an Easy-to-Use Platform for Multipurpose Applications

“…The concentration of the AuNP-dSol colloidal solution was 8.1 nmol L –1 by means of Lambert–Beer’s law, wherein the value of ε used was 2.7 × 10 8 L mol –1 cm –1 . 42 This result demonstrated that the particles were fully dispersed, and their size was almost in the same range with AuNPs-Cit and AuNPs-dSol without any contamination as a change in size or dispersibility would change the place of the absorption maxima. 47 It is a proven fact that by increasing the particle size of nanogold, the absorption maxima move toward a higher wavelength, resulting in a bathochromic (red) shift.…”

“…The maximum absorption band appeared at a wavelength of 520 nm for all three samples, which is a characteristic of 13 nm AuNPs. The concentration of the AuNP-dSol colloidal solution was 8.1 nmol L –1 by means of Lambert–Beer’s law, wherein the value of ε used was 2.7 × 10 8 L mol –1 cm –1 . This result demonstrated that the particles were fully dispersed, and their size was almost in the same range with AuNPs-Cit and AuNPs-dSol without any contamination as a change in size or dispersibility would change the place of the absorption maxima .…”

“…The concentration of this colloidal solution was estimated to be 8.01 nM according to Beer’s law while using an extinction coefficient (ε) of 13 nm AuNPs due to their surface plasmon resonance (SPR) wavelength at 520 nm. 42 In the second step, dextran-capped gold nanoparticles (AuNPs-dSol) were achieved by replacing citrate ions with dextran being the strong stabilizer as well as capping agent. This is called ″post-modification of pre-formed AuNPs″.…”

“…Keeping these issues in mind and in addition to our ongoing efforts to fabricate portable sensors for environmental monitoring and provide easy-to-use platforms, − we have developed a dextran-based AuNPs tablet (AuNPs-dTab) as a simple and ultrastable platform for multipurpose applications. These tablets can be prepared in different concentrations of colloidal gold with a variable amount of dextran; hence, a premeasured and calibrated/optimized amount of dextran-capped AuNPs can be stored in the form of solid tablets.…”

Rapid and selective detection of aluminum ion using 1,2,3-triazole-4,5-dicarboxylic acid-functionalized gold nanoparticle-based colorimetric sensor

“…Taking advantages of unique surface plasmon resonance (SPR) absorption, easy surface functionalization and variable solution colors, AuNPs have been used for colorimetric sensing in food security, environmental monitoring, and health care. 8–11 Potential applications include the determination of metal ions, 12–18 pesticide residues, 19,20 bisphenol A (BPA), 21,22 phosphate, 23 azodicarbonamide (ADA), 24 antibiotics, 25–27 adenosine and nucleic acids, 28–30 dopamine, 31 bacteria, 32,33 and virus. 34,35 …”