D-alanyl-D-alanine-Modified Gold Nanoparticles Form a Broad-Spectrum Sensor for Bacteria

Abstract

Rationale: Rapid and facile detection of pathogenic bacteria is challenging due to the requirement of large-scale instruments and equipment in conventional methods. We utilize D-amino acid as molecules to selectively target bacteria because bacteria can incorporate DADA in its cell wall while mammalian cells or fungi cannot.Methods: We show a broad-spectrum bacterial detection system based on D-amino acid-capped gold nanoparticles (AuNPs). AuNPs serve as the signal output that we can monitor without relying on any complex instruments.Results: In the presence of bacteria, the AuNPs aggregate and the color of AuNPs changes from red to blue. This convenient color change can distinguish between Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA). This system can be applied for detection of ascites samples from patients.Conclusion: These D-amino acid-modified AuNPs serve as a promising platform for rapid visual identification of pathogens in the clinic.

Hydrophobic Forces Are Relevant to Bacteria-Nanoparticle Interactions: Pseudomonas putida Capture Efficiency by Using Arginine, Cysteine or Oxalate Wrapped Magnetic Nanoparticles

“…In addition, bacteria capture experiments in a pH range from 2 to 11 [33] and from 4 to 10 [21] were performed, showing that the amino functionalized magnetic nanoparticles can capture E. coli independently from the acidity of the solution. In a recent work, gold NPs modified with the dipeptide L-alanyl-L-alanine negative charged show strong interactions with identically charged Gram-negative and -positive bacteria, interactions that are not fully explained in this work [42]; alanine is classified as an hydrophobic amino acid and this force could be relevant in the NP-bacteria interactions. Figure S5.…”

Nano-Strategies to Fight Multidrug Resistant Bacteria—“A Battle of the Titans”

“…NPs applications in biodetection is huge and more insights on pathogen detection using NPs platforms can be seen in Veigas et al ( 2013 , 2014 , 2015 ); Costa et al ( 2014 ); Weng et al ( 2015 ); Kim J. et al ( 2017 ); Wang et al ( 2017b ); Galvan and Yu ( 2018 ), and Yang et al ( 2018 ).…”

“…NPs have also been applied with tremendous success in biodetection systems, namely as sensors and diagnostics platforms with increased sensitivity and selectivity. Due to the decrease in size of the transduction mechanisms provided by NPs, most of these platforms have found applications at point-of-need and/or point-of-care (Costa et al, 2014 ; Veigas et al, 2014 ; Weng et al, 2015 ; Kim J. et al, 2017 ; Wang et al, 2017b ; Galvan and Yu, 2018 ; Yang et al, 2018 ). In some cases, diagnostics/sensing and therapeutic properties have been combined onto single NPs, providing for innovative tools – Nanotheranostics.…”

Rapid naked-eye detection of Gram-positive bacteria by vancomycin-based nano-aggregation

“…27,28 Rapid sensing technologies utilizing uorescence, magnetic, or colorimetric detection have been introduced as novel approaches as diagnostic assays for various disease targets. [29][30][31][32][33][34][35][36][37][38][39][40] Among these, a colorimetric detection method allowing nakedeye detection would be advantageous and easily applicable as a bedside assay in point-of-care settings. Detection based on molecularly induced aggregation have been usefully applied since they can be designed as a simple assay involving a onestep, wash-free procedure.…”

“…29,30 Aggregation-based assays using gold nanoparticles have been one of the most widely studied, and have been applied for diagnosing diseases such as cancer and infectious diseases. [31][32][33][34][35][36] For bacteria, studies based on the aggregation of gold nanoparticles utilizing concanavalin A, 34 cell wall peptide subunits, 35 and boronic acid derivatives 36 were reported, however could not distinguish various types of Grampositive pathogens from Gram-negative bacteria. Another method using platinum-coated magnetic nanoparticle clusters for immunoseparation and colorimetric detection has been reported, however a washing step was required and also allowed the detection of a single type of pathogen.…”