Porous Silicon Biosensor for the Detection of Bacteria through Their Lysate

Abstract

Porous silicon (PSi) has been widely used as a biosensor in recent years due to its large surface area and its optical properties. Most PSi biosensors consist in close-ended porous layers, and, because of the diffusion-limited infiltration of the analyte, they lack sensitivity and speed of response. In order to overcome these shortcomings, PSi membranes (PSiMs) have been fabricated using electrochemical etching and standard microfabrication techniques. In this work, PSiMs have been used for the optical detection of Bacillus cereus lysate. Before detection, the bacteria are selectively lysed by PlyB221, an endolysin encoded by the bacteriophage Deep-Blue targeting B. cereus. The detection relies on the infiltration of bacterial lysate inside the membrane, which induces a shift of the effective optical thickness. The biosensor was able to detect a B. cereus bacterial lysate, with an initial bacteria concentration of 105 colony forming units per mL (CFU/mL), in only 1 h. This proof-of-concept also illustrates the specificity of the lysis before detection. Not only does this detection platform enable the fast detection of bacteria, but the same technique can be extended to other bacteria using selective lysis, as demonstrated by the detection of Staphylococcus epidermidis, selectively lysed by lysostaphin.

Indirect Detection of Bacteria on Optically Enhanced Porous Silicon Membrane-Based Biosensors Using Selective Lytic Enzymes

“…Lower concentrations could be detected, but not without a risk of false negatives. This sensitivity was much improved compared to previous works, as the LoD is lowered by two orders of magnitude. , This improvement can not only be linked to the upgraded stability and enhanced optical properties but may also be attributed to electrostatic and hydrophilic effects. Indeed, TiO2 is reported as positively charged at physiological pH, while the bacterial lysate is mainly negatively charged. , Moreover, TiO 2 was also observed to be more hydrophilic than ALD-Al 2 O 3 , which was tested as passivation in a previous study .…”

“…This sensitivity was much improved compared to previous works, as the LoD is lowered by two orders of magnitude. 17,18 This improvement can not only be linked to the upgraded stability and enhanced optical properties but may also be attributed to electrostatic and hydrophilic effects. Indeed, TiO2 is reported as positively charged at physiological pH, while the bacterial lysate is mainly negatively charged.…”

“…The protocol of detection is illustrated in Figure and has already demonstrated promising results in previous works. , In this paper, the biosensor prototype was optimized and atomic layer deposition (ALD) was used to enhance the optical properties of the PSiMs by coating a more reflective metal oxide inside the porous matrix, to passivate the porous matrix, and to prevent its spontaneous dissolution in aqueous media. , Titanium oxide (TiO 2 ) was selected for this deposition based on its passivation and biosensing performances (see the Supporting Information), and the properties of TiO 2 -coated PSiMs are detailed. Bacillus cereus was selected as the model bacterial species for the detection, while the bacteriophage-encoded endolysin PlyB221 was used to induce selective lysis .…”

Porous nanomaterials for biosensing and related biological application in in vitro/vivo usability

“…This detection platform not only enabled the rapid detection of bacteria, but the same technique could be extended to other bacteria by selective lysis, such as the detection of Staphylococcus epidermidis and selective lysozyme lysis. 47 Layouni et al combined peptides with a multifunctional PSi optical biosensor platform for the detection of the chikungunya virus E2 protein. Peptide functionalization and selective E2 protein capture were confirmed by contact angle measurements, attenuated total reflection-Fourier transform infrared spectroscopy and optical reflectance measurements, and this biosensor could be exposed to high-temperature environments.…”

Metal Assisted Stain Etched Porous Silicon for Detecting Klebsiella Bacteria

“…The porous silicon is assumed to be a desirable transducing substrate for biosensing reasons with applications in several scientific disciplines due to its low cost of manufacture, large internal surface area, variable pore size and optical features (Moretta, De Stefano, Terracciano, & Rea, 2021;Vercauteren, Leprince, Mahillon, & Francis, 2021). Additionally, it has a hard structure that gives a chance to use it more than one time (Yaghoubi, Rahimi, Negahdari, Rezayan, & Shafiekhani, 2020).…”