Abstract
In designing a bacteria biosensor, various issues must be addressed: the specificity of bacteria recognition, the immobilization of biomolecules that act as the bacteria receptor, and the selectivity of sensor surface. The aim of this paper was to examine how the biofunctionalized surface of Ti, Au, and Ru metals reacts in contact with strains of Escherichia coli (E. coli). The focus on metal surfaces results from their future use as electrodes in high frequency biosensors, e.g., resonant circuits or transmission-line sections. First, the surfaces of different metals were chemically functionalized with 3-aminopropyltriethoxysilane (APTES) and glutaraldehyde or with 3-glycidylooxypropyltrimethoxysilane (GPTMS) followed by N-(5-amino-1-carboxypentyl) iminodiacetic acid (AB-NTA) and NiCl2. Secondly, the lipopolysaccharide binding protein (LBP), polyclonal anti-Escherichia coli antibody and bacteriophage protein gp37 were tested as bacteria receptors. The selectivity and specificity have been confirmed by the Enzyme-Linked Immunosorbent Assay (ELISA) and visualized by scanning electron microscopy at low landing energies. We noticed that LBP, polyclonal antibody, and gp37 were successfully immobilized on all studied metals and recognized the E. coli bacteria selectively. However, for the antibody, the highest reactivity was observed when Ti surface was modified, whereas the bacteria binding was comparable between LBP and gp37 on the functionalized Ru surfaces, independent from modification. Thus, all surfaces were biocompatible within the scope of biosensor functionality, with titanium functionalization showing the best performance.
Highlights
The rapid and precise detection of microorganisms through the development of modern biosensors accelerates implementation of appropriate treatment of infections and prevents major complications
We showed how the sensor material may affect the ability of bacteria detection by biomolecules that demonstrated high selectivity and specificity of Escherichia coli detection in Enzyme-Linked Immunosorbent Assay (ELISA) test
We studied several metals for composing conductor electrodes, for which Ti, Au, and Ru with very good electrical properties have been selected; the selected metals can be processed using well-established deposition methods on sensor surfaces, such as magnetron sputtering
Summary
The rapid and precise detection of microorganisms through the development of modern biosensors accelerates implementation of appropriate treatment of infections and prevents major complications. Detection and identification of pathogens is based on conventional microbiological techniques, biochemical, molecular biology, or serological methods [1,2]. Sensors 2018, 18, x FOR PEER REVIEW fairly rapid identification, they show a number of disadvantages, such as: multi-step processes of labeling of different cell compartments and destructive preparation workflows [3]. To overcome these limitations label-free biosensing detection methods have been proposed [4]. The increasing number of publications on label-free methods confirms the possibility to utilize cost-effective biosensors for various cells detection [5,6,7,8].
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