Preparation of gold nanoparticles by microwave heating and application of spectroscopy to study conjugate of gold nanoparticles with antibody E. coli O157:H7

Abstract

Gold nanoparticles (AuNPs) of 15-20 nm size range have attracted attention for producing smart sensing devices as diagnostic tools in biomedical sciences. Citrate capped AuNPs are negatively charged, which can be exploited for electrostatic interactions with some positively charged biomolecules like antibodies. In this paper we describe a method for the low cost synthesis of gold nanoparticles using sodium citrate (Na 3 Ct) reduction in chloroauric acid (HAuCl 4 .3H 2 O) by microwave heating (diameter about 13-15 nm). Gold nanoparticles were functionalized with surface activation by 3-mercaptopropionic acid for attaching antibody. These nanoparticles were then reacted with anti-E. coli O157:H7, using N-hydroxy succinimide (NHS) and carbondimide hydrochloride (EDC) coupling chemistry. The product was characterized with UV-visible spectroscopy, Fourier transform infrared (FTIR) spectroscopy and zeta potential. In addition, the binding of antibody-gold nanoparticles conjugates to E. coli O157:H7 was demonstrated using transmission electron microscopy (TEM).

Immunogold Nanoparticles for Rapid Plasmonic Detection of C. sakazakii

“…Wang and Alocilja recently demonstrated a rapid and sensitive method for bacterial detection reaching a sensitivity of 10 CFU/mL with a linear range of 10 1 –10 6 CFU/mL for E. coli O157:H7 [ 25 ]. They used polymer-coated magnetic nanoparticles to first extract E. coli O157:H and then performed a sandwich assay for electrochemical readout of Au nanoparticles targeted to the extracted E. coli , which could be completed within 1 h. Ngo et al (2015) also attempted labeling for transmission electron microscopy, UV-Vis spectroscopy and FTIR of E. coli O157:H7 with Au nanoparticles (12–14 nm diameter) stabilized by thiol surfactant (3-mercaptopropionic) and directly conjugated with anti- E. coli O157:H7 antibodies [ 26 ]. An additional report on the detection of E. coli 0157:H7 in urine sample used Au NPs conjugated with cysteine and unspecific electrostatic adhesion to E. coli [ 27 ].…”

Microwave-Driven Synthesis of Iron-Oxide Nanoparticles for Molecular Imaging

“…Results yielded highly stable AuNPs with diameters of ~4.0 nm and ~1.0 nm depending on the MW irradiation time (40 s and 70 s, respectively_. Similarly, Thanh Ngo et al [85] made use of MW heating for the synthesis of antibody functionalized AuNPs (13–15 nm in diameter) with antibacterial activity. HAuCl 4 and Na 3 Ct were used as precursors for the synthesis of the AuNPs, which were posteriorly functionalized with an antibody against E. coli O157:H7, using N -hydroxy succinimide (NHS) and carbodimide hydrochloride (EDC) coupling chemistry.…”

Controllable Synthesis of Gold Nanoparticles in Aqueous Solution by Microwave Assisted Flow Chemistry

“…[4][5][6][7][8][9] In order for high yield synthesis of Au-NPs with well-defined shape and size, the Turkevich method has been extensively modified such as by changing the addition order of the reactants, using different reducing agents, adjusting the ratio of HAuCl4 to sodium citrate and pH values as well as adding new stabilisers. [10][11][12][13][14][15][16][17][18] Replacement of water by its expensive isotope, deuterium oxide, was shown to produce smaller sizes of Au NPs (5.3 ± 1.1 nm), compared with the particles (9.0 ± 1.2 nm) produced in pure water which was attributed to faster reduction of precursor. 19 An increase in reaction rate was observed by reversing the order of the reactants' addition (i.e.…”

“…2,7-dihydroxy naphthalene as the reducing agent and cetyltrimethyl ammonium bromide as the stabilizer). 16,[24][25][26][27] These studies generally used domestic multimode microwave systems (600-1000 W) and their results revealed that microwave assisted fast temperature ramping was highly effective to synthesize Au-NPs (e.g. 20.01 (±2.05) nm or 12.04 (±1.35) nm).…”