Abstract:Sensors composed of a porous silicon monolayer covered with a film of nanostructured gold layer, which provide two optical signal transduction methods, are fabricated and thoroughly characterized concerning their sensing performance. For this purpose, silicon substrates were electrochemically etched in order to obtain porous silicon monolayers, which were subsequently immersed in gold salt solution facilitating the formation of a porous gold nanoparticle layer on top of the porous silicon. The deposition proce… Show more
“…Solutions, such as the electrokinetic transport for the preconcentration of analyte, have been proposed but remain to be tested on bacteria [29]. Recently, porous silicon interferometers have also been combined with gold nanoparticles for localized surface plasmon spectroscopy (LSPS), enhancing the fringe pattern contrast and increasing the sensitivity of the porous layer [30,31].…”
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.
“…Solutions, such as the electrokinetic transport for the preconcentration of analyte, have been proposed but remain to be tested on bacteria [29]. Recently, porous silicon interferometers have also been combined with gold nanoparticles for localized surface plasmon spectroscopy (LSPS), enhancing the fringe pattern contrast and increasing the sensitivity of the porous layer [30,31].…”
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.
“…PSi nanostructures have been used as a host matrix for preparing hybrid platforms using different nanomaterials such as QDs, MNPs, graphene oxide, carbon nanotubes, fluorescent molecules, and polymers (Arshavsky-Graham et al, 2018;Tieu et al, 2019). PSi-based hybrid platforms improve the sensitivity and stability of the sensor and allow for dual-mode detection (Gaur et al, 2013;Pacholski et al, 2019). PSi biosensors designed with single-mode optical sensing suffer from poor sensitivity limited to the micromolar range and lack of simultaneous selective detection of more than one target analyte (Massad-Ivanir et al, 2018b).…”
Section: Psi-based Hybrid Biosensorsmentioning
confidence: 99%
“…In contrast, optical biosensors designed for dual-mode detection are characterized by their ability to combine the quantification and identification of molecules in a single substrate (Jiao et al, 2010;Yeom et al, 2011). The molecular quantification can be achieved via reflectance measurements of PSi matrix, whereas the molecular identification and conformation can be attained through Surface Enhanced Raman Spectroscopy (SERS) (Jiao et al, 2010;Pacholski et al, 2019) or LSPR (Pacholski et al, 2019) in case of using MNPs, or through fluorescence spectroscopy when fluorescent QDs are confined inside the PSi matrix (Massad-Ivanir et al, 2018a,b). The dual-mode biosensors with fluorescence or SERS characteristic enable the detection of multiple molecules with enhanced sensitivity and specificity (McNay et al, 2011).…”
Section: Psi-based Hybrid Biosensorsmentioning
confidence: 99%
“…A recent review by Bandarenka et al discussed the fabrication of PSi/metal nanoparticles hybrids and their application as SERS-active substrates, emphasizing two major advantages: (1) the long storage stability; and (2) the significant Raman enhancement factor (Bandarenka et al, 2018). PSi/Plasmonic nanoparticle hybrids allow for fabricating biosensors with SERS and refractive index sensing capability (Pacholski et al, 2019). Škrabi'c et al reported the application of silver-coated PSi photonic crystals as SERS substrates for nearinfrared (1064 nm) excitation, which has significant importance for the Raman detection of fragile biomolecules (Škrabić et al, 2019).…”
During the last two decades, porous silicon (PSi) has been proposed as a high-performance biosensing platform due to its biocompatibility, surface tailorability, and reproducibility. This review focuses on the recent developments and progress in the area related to hybrid PSi biosensors using plasmonic metal nanoparticles (MNPs), fluorescent quantum dots (QDs), or a combination of both MNPs and QDs for creating hybrid nanostructured architectures for ultrasensitive detection of biomolecules. The review discusses the mechanisms of sensitivity enhancement based on Localized Surface Plasmon Resonance (LSPR) of MNPs, Fluorescence Resonance Energy Transfer (FRET) in the case of MNPs/QDs donor-acceptor interactions, and photoluminescence/fluorescence enhancement resulting from the embedded fluorescent QDs inside the PSi microcavity. The review highlights the key features of hybrid PSi/MNPs/QDs biosensors for dual-mode detection applications.
“…The wavelength of the plasmon resonance depends not only on the Au nanostructures but also on the refractive index of the surrounding medium. Plasmon resonance is sensitive to changes in the refractive index only close to the dielectric/metal interface [89]. Metal decorated porous silicon structures are feasible as sensors, especially to detect molecules.…”
Section: Optical Properties Of Metal Filled Mesoporous Siliconmentioning
Within this work the utilization of nanostructured silicon as host material for filling with various magnetic nanostructures is reviewed whereas the magnetic and optical properties of the gained composite systems are elucidated. The metal filling of the pores is mainly performed by electroless deposition or by electrodeposition which is discussed by means of some examples. Furthermore, two different types of porous silicon (PSi) morphology are used for the deposition procedure. On the one hand microporous silicon offering luminescence in the visible range is utilized as template material. It offers a branched morphology with a structure size between 2 and 5 nm. In this case not only the magnetic response is investigated but also the influence of the metal filling on the optical properties. On the other hand mesoporous and macroporous silicon in it's low pore regime is employed which offers straight pores with diameters up to 90 nm. In this case the magnetic response strongly depends on the size, the geometry and the spatial distribution of the metal deposits within the pores. A crucial role plays also the morphology of the porous silicon, especially the distance between adjacent pores which is an important parameter regarding magnetic interactions.
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