Gold Nanoparticle-Coated Starch Magnetic Beads for the Separation, Concentration, and SERS-Based Detection of E. coli O157:H7

Abstract

Here, we report gold nanoparticle-coated starch magnetic beads (AuNP@SMBs) that were prepared by in situ synthesis of AuNPs on the surface of SMBs. Upon functionalization of the surface with a specific antibody, the immuno-AuNP@SMBs were found to be effective in separating and concentrating the target pathogenic bacteria, Escherichia coli O157:H7, from an aqueous sample as well as providing a hotspot for surface-enhanced Raman scattering (SERS)-based detection. We employed a bifunctional linker protein, 4× gold-binding peptide-tagged Streptococcal protein G (4GS), to immobilize antibodies on AuNP@SMBs and AuNPs in an oriented form. The linker protein also served as a Raman reporter, exhibiting a strong and unique fingerprint signal during the SERS measurement. The amplitude of the SERS signal was shown to have a good correlation with the concentration of target bacteria ranging from 100 to 105 CFU/mL. The detection limit was determined to be as low as a single cell, and the background signals derived from nontarget bacteria were negligible due to the excellent specificity and colloidal stability of the immuno-AuNP@SMBs and SERS tags. The highly sensitive nature of the SERS-based detection system will provide a promising means to detect the pathogenic microorganisms in food or clinical specimen.

Plasmonic Gold Nanoisland Film for Bacterial Theranostics

“…For the AuNIF without E. coli, there were two Raman signals at 1543 and 1579 cm −1 due to the characteristic peak of carboxyl groups on the surface of the AuNIF. After culturing E. coli on the AuNIF, the characteristic Raman signals of E. coli were observed at 744, 911, 1115, 1221, 1321, 1368, 1453, 1585, and 1623 cm −1 (Table 1) [48][49][50]. Results of Raman measurements indicate that the plasmonic AuNIF can be applied as a promising SERS substrate that enhances E. coli Raman signals.…”

Immunocapture Magnetic Beads Enhanced the LAMP-CRISPR/Cas12a Method for the Sensitive, Specific, and Visual Detection of Campylobacter jejuni

“…The ICB-LAMP-CRISPR/ Cas12a method developed herein could specifically recognize and capture free C. jejuni in fecal samples within 20 min using the C. jejuni antibody-coated magnetic beads. This improved the sensitivity and specificity from the source of the detection method (Figure 1) [42]. Conventional nucleic acid amplification methods require at least 1 × 10 3 CFU/mL of colonies as a template to perform normal amplification [43,44], while sample enrichment by ICB in the ICB-LAMP-CRISPR/Cas12a method could reach a detection limit of 8 × 10 0 CFU/mL.…”

Broad-Spectrum Theranostics and Biomedical Application of Functionalized Nanomaterials

“…In a study, it was reported that gold nanoparticle-coated starch magnetic beads were synthesized and functionalized using specific antibodies (immuno-AuNP@SMBs), which were found to be effective in separating and concentrating the target pathogenic bacteria, Escherichia coli O157:H7, and is also involved in surface-enhanced Raman scattering (SERS)-based detection. Thus, it is suggested that a SERS-based detection system helps in detecting pathogenic microorganism in clinical and food samples [ 210 ]. In another study, gold nanoparticles were functionalized with tau-specific monoclonal antibodies and an oligonucleotide template for an immuno-polymerase chain reaction (Nano-iPCR).…”