Chitosan Stabilized Silver Nanoparticles for the Electrochemical Detection of Lipopolysaccharide: A Facile Biosensing Approach for Gram-Negative Bacteria

Abstract

Negatively charged lipopolysaccharide (LPS), a major endotoxin and component of the outer membrane of several Gram-negative bacteria, provides a useful biomarker for the indirect detection of these pathogens. For instance, Escherichia coli (E. coli) is a pathogenic bacterium that causes infections in almost all age groups, and has been implicated in food and water contamination. Current diagnostic and detection methods tend to be labor-intensive or expensive, necessitating the need for an easy, sensitive, rapid, and low-cost method. We report on the synthesis and use of positively charged chitosan stabilized silver nanoparticles (Chi-AgNPs) as a sensitive electrochemical nanobiosensor for the detection of LPS. Chi-AgNPs were synthesized through a facile, single step protocol, and characterized for size, charge, and morphology. Glassy carbon electrodes modified with Chi-AgNPs resulted in an enhancement of signal in the presence of both LPS and E. coli. Detection was accomplished over a large concentration range (several orders of magnitude) of 0.001–100 ng/mL and 10–107 CFU/mL. The biosensors can reliably detect LPS and E. coli at very low concentrations. Chi-AgNPs have potential as low cost, sensitive nanobiosensors for Gram-negative bacteria due to strong electrostatic interaction with LPS present in their outer membranes.

Interactions of Gold and Silver Nanoparticles with Bacterial Biofilms: Molecular Interactions behind Inhibition and Resistance

“…In a different study, authors used a positively charged chitosan polymer for coating and stabilizing AgNPs (chitosan-AgNPs). The chitosan layer on AgNPs interacted strongly with the negatively charged LPS molecules [ 55 ]. The authors used these interactions in order to make an ultrasensitive sensor for Gram-negative model microorganism E. coli [ 55 ].…”

“…The chitosan layer on AgNPs interacted strongly with the negatively charged LPS molecules [ 55 ]. The authors used these interactions in order to make an ultrasensitive sensor for Gram-negative model microorganism E. coli [ 55 ]. Mitzel and Tufenkji reported an unusual observation where they used quartz sand surface coated with P. aeruginosa biofilm for checking biofilm interaction with poly(vinyl pyrrolidone)-coated silver nanoparticles (PVP-AgNPs) [ 56 ].…”

A Review on the Development of Gold and Silver Nanoparticles-Based Biosensor as a Detection Strategy of Emerging and Pathogenic RNA Virus

“…Whereas for AgNPs, the common stabilizing agents include the anionic species, such as halides, carboxylates, or polyoxoanions that impart a negative charge on the surface of AgNPs, and cationic species such as polyethyleneimine (PEI) and chitosan that create highly positive charges on the AgNPs surface [ 70 ]. In a study carried out by Imran et al [ 71 ], chitosan was used as the reducing agent as well as stabilizing agent for the synthesis of AgNPs. The choice of ligands used to stabilize AgNPs based on steric hindrance include organic polymers, such as poly(vinyl alcohol) (PVA) [ 72 ], poly(vinylidene fluoride) (PVDF) [ 73 ], and polyethylene glycol (PEG) [ 74 ].…”

Nanomaterials in the Management of Gram-Negative Bacterial Infections

“…Labeled gold NPs A perfect Detect of E. coli 500 CFU mL −1 in 1 mL of sample [75] DNA-gold NPs Detection of bacteria with low concentration of 2 × 10 3 CFU mL −1 [76] Protein-gold NPs No cross-reactivity for Gram-negative pathogens [77] gold@MoS 2 -PANI nanocomposite 10 CFU mL −1 for LOD in just 30 min [78] Peptide-gold NPs LOD and LOQ for E. coli measurement was 2 and 6 CFU mL −1 , respectively [79] Protein-gold NPs A perfect LOD of 4 × 10 3 CFU mL −1 , reusable potential, and wide-range analysis of 2 × 10 4 -2 × 10 7 CFU mL −1 for E. coli detection [80] Ag NPs Ag-gold alloy nanohole arrays Label-free detection, wide-range analysis of 10 3 -10 8 CFU mL −1 and LOD of 59 CFU mL −1 [81] Polymer-Ag NPs Wide range analysis of 0.001-100 ng mL −1 and 10-10 7 CFU mL −1 [82] QDs Mannose-ZnTe QDs Good selectivity and a perfect linearity range of 1.0 × 10 5 -1.0 × 10 8 CFU mL −1 toward E. coli [83] CdS QDs@MOF Suitable linear range of 10-10 8 CFU mL −1 , LOD of 3 CFU mL −1 and S/N of 3 [84] carboxylated graphene QD Detection of pathogen in drinking water in low concentrations of E. coli (10 3 -10 6 CFU mL −1 ) [85] Carbon nanomaterials [98]. In this light, Li et al developed a procedure for detecting the E. coli O157:H7 bacteria by using gold NP labelling, antibody affinity binding, and inductively coupled plasma mass spectrometry (ICPMS) [75].…”

“…In another study, for the construction of a new biosensor, a polymer-metal method was also used. Imran et al developed a sensitive electrochemical nanobiosensor using positively charged chitosan stabilized silver NPs (Chi-silver NPs) for the identification of negatively charged lipopolysaccharide (LPS) or E. coli [82]. In the presence of both LPS and E. coli, glassy carbon electrodes treated with Chi-silver NPs increased its signal.…”