Surface Plasmon Resonance Based Label-Free Detection of Salmonella using DNA Self Assembly

Abstract

Typhoid is re-emerging as a biggest health threat to third world countries. One of the major challenge is false negative diagnosis using existing immunodiagnostic methods due to overlapping symptoms of other infections (like brucellosis, malaria, hepatitis) that mimic this enteric fever (typhoid). Surface plasmon resonance (SPR) based DNA hybridisation biosensor has been fabricated by generating self-assembled monolayer of 5'-thiolated single-stranded DNA (ssDNA) probe onto gold surface. Highly specific DNA probe has been selected from conserved Vi capsular antigen gene of Salmonella enterica serovars typhi. This DNA biosensor has been investigated for label-free real-time monitoring of Salmonella. Interestingly, 0.019 ng mL(-1) (2 fM) is the lowest detected concentration in PBS with association (k a) and dissociation (k d) rate constants to be k a (M(-1) s(-1)) = 6.68 × 10(4) ± 2.3 and k d (s(-1)) = 5.6 × 10(-3) ± 0.01, respectively. This biosensor was successfully demonstrated to distinguish complementary, non-complementary and one-base mismatch sequences and reusability up to 40 hybridisation cycles at room temperature. Successful results were obtained for hybridisation studies of genomic DNA isolated from spiked urine sample. Performance characteristics of this biosensing device suggested further scope to fine-tune such DNA-based assays to be implied for clinical, food and environmental applications.

Prevalence of current patterns and predictive trends of multidrug-resistant Salmonella Typhi in Sudan

“…From the recovered bacteria species, 128 were identified as Salmonella Typhi, the isolates stereotyping showed that; 9 groups (75%) had the antigenic formula O:9(D 1 ) for Salmonella Typhi, 3 groups (25%) had the formula Salmonella enteric Paratyphi A 1,2,12 a [ 1 , 5 ] and Salmonella enterica Paratyphi C1 6,7,[Vi] c 1,5 respectively.…”

“…Globally the burden of typhoid fever victims are 20 million as a main issue of morbidity and mortality in developing countries [ 1 , 2 ]. In Sudan, approximate numbers of typhoid infection is increasing during rainy season in association with malaria incidents [ 3 – 5 ].…”

Laboratory Diagnosis of Paratyphoid Fever: Opportunity of Surface Plasmon Resonance

“…An SPR-based genoassay has been performed to detect S. Typhi based on thiolated self-assembled monolayer of single-stranded DNA (ssDNA) as a DNA probe, which is designed for the Vi-antigen gene of S. Typhi [ 130 ]. In this study, specific ssDNA probes were immobilized onto gold film, and the assay records the lowest detection concentration (0.019 ng/mL −1 ), when compared to several other SPR-based bacterial detection studies ( Table 3 ).…”

Gene Specific DNA Sensors for Diagnosis of Pathogenic Infections

“…Another group has assembled a SPR based DNA hybridization biosensor immobilized with ssDNA probe complementary to conserved Vi capsular protein of Salmonella enteric Serovars typhi. The biosensor works at room temperature up to 40 hybridization cycles and differentiate between complementary and mismatched sequences [38].…”