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Every year about one million people die due to diseases transmitted by mosquitoes. The infection is transmitted to a person when an infected mosquito stings, injecting the saliva into the human body. The best possible way to prevent a mosquito-borne infection till date is to save the humans from exposure to mosquito bites. This study proposes a Machine Learning (ML) and Deep Learning based system to detect the presence of two critical disease spreading classes of mosquitoes such as the Aedes and Culex. The proposed system will effectively aid in epidemiology to design evidence-based policies and decisions by analyzing the risks and transmission. The study proposes an effective methodology for the classification of mosquitoes using ML and CNN models. The novel RIFS has been introduced which integrates two types of feature selection techniques – the ROI-based image filtering and the wrappers-based FFS technique. Comparative analysis of various ML and deep learning models has been performed to determine the most appropriate model applicable based on their performance metrics as well as computational needs. Results prove that ETC outperformed among the all applied ML model by providing 0.992 accuracy while VVG16 has outperformed other CNN models by giving 0.986 of accuracy. [ABSTRACT FROM AUTHOR]

Aptamer biosensors are one of the most powerful techniques in biosensing. Achieving the best platform to use in aptamer biosensors typically includes crucial chemical modifications that enable aptamer immobilization on the surface in the most efficient manner. These chemical modifications must be well defined. In this work we propose nanoporous anodic alumina (NAA) chemically modified with streptavidin as a platform for aptamer immobilization. The immobilization of biotinylated thrombin binding aptamer (TBA) was monitored in real time by means of reflective interferometric spectroscopy (RIfS). The study has permitted to characterize in real time the path to immobilize TBA on the inner pore walls of NAA. Furthermore, this study provides an accurate label-free method to detect thrombin in real-time with high affinity and specificity.

The chemical modification, or functionalization, of the surfaces of nanomaterials is a key step to achieve biosensors with the best sensitivity and selectivity. The surface modification of biosensors usually comprises several modification steps that have to be optimized. Real-time monitoring of all the reactions taking place during such modification steps can be a highly helpful tool for optimization. In this work, we propose nanoporous anodic alumina (NAA) functionalized with the streptavidin-biotin complex as a platform towards label-free biosensors. Using reflective interferometric spectroscopy (RIfS), the streptavidin-biotin complex formation, using biotinylated thrombin as a molecule model, was monitored in real-time. The study compared the performance of different NAA pore sizes in order to achieve the highest response. Furthermore, the optimal streptavidin concentration that enabled the efficient detection of the biotinylated thrombin attachment was estimated. Finally, the ability of the NAA-RIfS system to quantify the concentration of biotinylated thrombin was evaluated. This study provides an optimized characterization method to monitor the chemical reactions that take place during the biotinylated molecules attachment within the NAA pores.

In this paper, the improvement in room temperature ethanol sensing characteristics of zinc peroxide (ZnO 2 ) based hybrid thin films is presented by the combination of the beneficial sensing properties of mesoporous materials and reflectometric interference spectroscopy (RIfS). The hybrid thin films were prepared by Layer-by-Layer (LbL) self-assembly method from ZnO 2 nanoparticles, polyelectrolyte [poly(acrylic acid), PAA] and/or mesoporous silica (MPS). The expected improved sensing properties were attributed to the fractal properties and high specific surface area ( a s ) of the mesoporous coating/interlayer material, which was evidenced by small angle X-ray scattering (SAXS) and N 2 sorption measurements (a s > 650 m 2 /g). The sensor tests showed that the detection limit of the thin films is in the sub-ppm range (<500 ppb). Applying silica foam (SF) as surface coating or interlayer material in the sandwich-structured thin film (ZnO 2 /SF) improved the optical response (Δl: wavelength shift) compared to the ZnO 2 /PAA thin layer, but the sensitivity showed non-linear characteristic and signal drift. The thin film with mixed structure (ZnO 2 /PAA/ZnO 2 /SF) showed linear sensitivity (Δλ/Δc = 0.6 nm/ppm) in the 0.5–12 ppm range with an acceptable selectivity and stable baseline. Testing the sensor in extended (up to 40 ppm) concentration range showed only a slight quadratic deviation from linear behavior with R 2 = 0.9987. [ABSTRACT FROM AUTHOR]

Using a biomedical sensor setup RIfS we have investigated the kinetic behavior of human albumin (Alb), human fibrinogen (Fib), and human immunoglobulin G (IgG) adsorbed onto surfaces of chitosan. Polystyrene (PS) was used as the control material in this study. The optical thickness of three kinds of proteins measured by RIfS was related to their molecular dimensions and potential orientations on a film surface. According to the operation principle of RIfS and the molecular dimensions of three kinds of proteins, the adsorbed layers of proteins onto the surface of chitosan and PS was calculated by using a newly introduced equation. The microstructure of the chitosan and polystyrene film and the surfaces with adsorbed proteins were imaged by atomic force microscopy (AFM). With AFM analyses the lateral distribution of the protein molecules on surfaces have been recognized. The results show that the number of adsorbed layers of the three proteins on the surface of chitosan are 0.635 for Alb, 0.158 for Fib and 0.0967 for IgG, and of polystyrene are: 0.577 for IgG, 0.399 for Fib, 0.336 for Alb. This study confirmed that RIfS is a useful tool for the analysis of plasma proteins adsorbed on a surface of biomaterials. Results show that at first on the surface of chitosan film much more Alb than Fib was adsorbed which demonstrated that chitosan has a antithrombus function. Secondly, on the surface of chitosan film more Alb and less Fib were adsorbed than on the surface of PS film, which demonstrated that chitosan has a better blood compatibility than polystyrene. Thirdly, the calculated layer number of the three proteins indicated that on both chitosan and PS substrates monolayer coatings form.

Membrane fluidity is a critical parameter of cellular membranes, which cells continuously strive to maintain within a viable range. Interference with the correct membrane fluidity state can strongly inhibit cell function. Triggered changes in membrane fluidity and associated impacts on lipid domains have been postulated to contribute to the mechanism of action of membrane targeting antimicrobials, but the corresponding analyses have been hampered by the absence of readily available analytical tools. Here, we expand upon the protocols outlined in the first edition of this book, providing further and alternative protocols that can be used to measure changes in membrane fluidity. We provide detailed protocols, which allow straightforward in vivo and in vitro measurement of antibiotic compound-triggered changes in membrane fluidity and fluid membrane microdomains. Furthermore, we summarize useful strains constructed by us and others to characterize and confirm lipid specificity of membrane antimicrobials directly in vivo., (© 2023. The Author(s), under exclusive license to Springer Science+Business Media, LLC, part of Springer Nature.)

Reflectometric interference spectroscopy (RIfS) was used to detect ethanol vapour in 10–100 ppm concentration on the surface of original and modified ZnO 2 thin films in a gas flow platform. The interference pattern shift (Δ λ ) caused by the increase of the effective refractive index (in general terms the optical thickness) of the thin film due to vapour adsorption into the pores was investigated. The effect of noise level was reduced by polynomial fitting, hence the limit of detection (LOD) was improved significantly (by half an order of magnitude). Similarly, by surface functionalization (with butyltrichlorosilane, BTS) the sensitivity to ethanol vapour was increased by one order of magnitude (from 0.038 to 0.331 nm/ppm), and the limit of detection improved three-fold as well. The RIfS method was compared to a gravimetric technique (quartz crystal microbalance, QCM), and at the same time the adsorbed vapour amount ( n s ) that gives rise of Δ λ was investigated: linear Δ λ vs. n s curves were determined in the 0–60 ppm concentration range. [ABSTRACT FROM AUTHOR]

Modifying the diameter of the pores in nanoporous anodic alumina opens new possibilities in the application of this material. In this work, we review the different nanoengineering methods by classifying them into two kinds: in situ and ex situ. Ex situ methods imply the interruption of the anodization process and the addition of intermediate steps, while in situ methods aim at realizing the in-depth pore modulation by continuous changes in the anodization conditions. Ex situ methods permit a greater versatility in the pore geometry, while in situ methods are simpler and adequate for repeated cycles. As an example of ex situ methods, we analyze the effect of changing drastically one of the anodization parameters (anodization voltage, electrolyte composition or concentration). We also introduce in situ methods to obtain distributed Bragg reflectors or rugate filters in nanoporous anodic alumina with cyclic anodization voltage or current. This nanopore engineering permits us to propose new applications in the field of biosensing: using the unique reflectance or photoluminescence properties of the material to obtain photonic barcodes, applying a gold-coated double-layer nanoporous alumina to design a self-referencing protein sensor or giving a proof-of-concept of the refractive index sensing capabilities of nanoporous rugate filters. [ABSTRACT FROM AUTHOR]

We present a portable and easy-to-use biosensor platform, allowing for label-free detection of diagnostic markers in undiluted animal serum. Exemplarily, this is shown for the detection of anti- Salmonella antibodies. 1-lambda-Reflectometry was used as detection method, making the new biosensor platform portable, cheap, and robust. As recognition elements, lipopolysaccharides (LPSs) from Salmonella typhimurium bacteria were immobilized as sensitive layer on the transducer to carry out serological tests via a direct assay format. For this purpose, a new surface preparation protocol has been worked out allowing for immobilization of the LPS via hydrophobic interactions. It has been shown that results obtained by 1-lambda-Reflectometry are equivalent to those obtained by the non-portable Reflectometric Interference Spectroscopy setup. The new sensor platform was calibrated in both matrices, buffer and undiluted serum. Good sensitivity, selectivity and intra chip reproducibility have been observed. Furthermore, inter chip reproducibility was examined and recovery rates were found to be between 99 and 117 % in undiluted serum. [ABSTRACT FROM AUTHOR]

Molecularly imprinted nanospheres obtained by miniemulsion polymerization have been applied as the sensitive layer for label-free direct optical sensing of small molecules. Using these particles as the sensitive layer allowed for improving response times in comparison to sensors using MIP layers. As a model compound, well-characterized nanospheres imprinted against l-Boc-phenylalanine anilide ( l-BFA) were chosen. For immobilization, a simple concept based on electrostatic adsorption was used, showing its applicability to different types of surfaces, leading to a good surface coverage. The sensor showed short response times, good selectivity, and high reversibility with a limit of detection down to 60 μM and a limit of quantitation of 94 μM. Furthermore, reproducibility, selectivity, and long-term stability of the sensitive layers were tested. The best results were achieved with an adsorption on aminopropylsilane layers, showing a chip-to-chip reproducibility of 22%. Furthermore, the sensors showed no loss in signal after a storage time of 1 year. [ABSTRACT FROM AUTHOR]

Abstract: An assay for the detection of H1N1 virus was established using Reflectometric Interference Spectroscopy (RIfS), a label-free optical detection method. A direct assay format was used to detect the virus by the corresponding antibody immobilized on the chip surface. The used surface chemistry showed low non-specific binding of the virions and gave reproducible signals. The binding of H1N1 virus was monitored in RIfS and verified by atomic force microscopy (AFM) measurements. The proposed assay has the potential to be integrated in portable and miniaturized devices based on RIfS, which can be used in point of care testing at e.g. airports to improve homeland security. [ABSTRACT FROM AUTHOR]

Abstract: We describe a new and rapid method for diagnosing tuberculosis-specific antibodies in undiluted human blood serum by surface sensitive biosensors. An integrated optical grating coupler, an interferometric biosensor and a device based on the reflectometric interference spectroscopy (BIAffinity, Analytik Jena AG) were used to determine tuberculosis-specific antibodies, which are present in blood serum of infected persons. The specific sensor surface was generated by immobilized 38-kDa tuberculosis antigen and real-time detection was performed without any label in all cases. Unspecific binding effects caused by serum proteins were suppressed by appropriate coupling chemistry. 1,4-Phenylenediisothiocyanate was used as a crosslinker for the coupling of the antigen achieving the effect of complete surface coverage. This enables label-free serodiagnosis of tuberculosis infection with a specificity of 100% and a sensitivity of 75%. Based on our results, we anticipate that a label-free detection procedure with one or more marker antigens is possible for a rapid, economical and accurate routine diagnosis of tuberculosis and other infectious diseases in the future. [Copyright &y& Elsevier]

Abstract: Recurrent bivariate fractal interpolation surfaces (RBFISs) generalise the notion of affine fractal interpolation surfaces (FISs) in that the iterated system of transformations used to construct such a surface is non-affine. The resulting limit surface is therefore no longer self-affine nor self-similar. Exact values for the box-counting dimension of the RBFISs are obtained. Finally, a methodology to approximate any natural surface using RBFISs is outlined. [Copyright &y& Elsevier]

This paper describes the combination of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry with label free bio-interaction analysis based on reflectometric interference spectroscopy (RIfS). The potential of this concerted approach is demonstrated by measuring the binding properties of different vancomycin-type glycopeptide antibiotic mixtures. Although RIfS is sensitive and does not require use of a label, it cannot determine which components of a mixture have bound to the surface after incubation. Fortunately, each bound species has a unique mass that can, afterwards, be determined by mass spectrometry. Thus, the screening capability of RIfS is combined with the identification capability of mass spectrometry. [ABSTRACT FROM AUTHOR]

Objectives. Plaque accumulation, leading to inflammatory processes and bone loss, is one of the main reasons for failure of dental implants. Pellicle formation plays a key role in bacterial adhesion and plaque accumulation. The influence of experimental bioactive implant surface coatings on the initial process of pellicle formation was investigated in a model system.Methods. TiO2-films were modified by covalent binding of laminin and human epidermal growth factor (EGF) to promote adhesion of epithelial cells. Adsorption and dissociation behavior of bovine serum albumin (BSA) and salivary proteins on these surfaces were monitored by time-resolved reflectometric interference spectroscopy (RIfS).Results. The thickness of the irreversibly adsorbed salivary protein layer was reduced from 2.78±0.71 nm on unmodified TiO2 to 0.78±0.22 nm on laminin-coated surfaces and to 1.18±0.29 nm on EGF-coated surfaces. The percentage of initially adsorbed proteins remaining irreversibly bound was reduced from 51±8% on titanium to 23±5% by laminin coating and to 44±11% on EGF-coated surfaces. The highest reduction of protein adsorption (layer thickness lower than 0.05 nm) was achieved on DC-PEG-layers used as spacer for protein coupling.Significance. Laminin and EGF were shown to be promising candidates for use as biological coatings on the transmucosal part of titanium dental implants where the objective is to enhance epithelial adhesion and inhibit adsorption of salivary proteins and bacteria. [Copyright &y& Elsevier]

Using the optical measurement technique reflectometric interference spectroscopy (RIfS), the interaction of molecularly imprinted polymers (imprinted with either (R,R)- or (S,S)-2,3-di-O-benzoyltartraric acid) with the corresponding templates and template antipodes were investigated. With these sensors chiral separation with a separation factor of 1.2 could be achieved whereas a reference polymer resulted in no separation. RIfS signals were of opposite sign for imprinted polymer layers containing phenylboronic acid binding site monomers. [ABSTRACT FROM AUTHOR]

Picture encoding methods based on the iterated function system (IFS) have been reported. However, they are designed for still pictures and few reports have been made for moving pictures. This paper proposes a coding method for moving pictures based on the recurrent iterated function system (RIFS). In RIFS, the function systems of contraction mappings in multiple spaces are composed. In this study, it is assumed that by using a sequence of moving pictures for multiple spaces, moving pictures can be coded. In this proposed method, several frames are treated as a group and the search in coding is adaptively switched, using the block (range cell) of each frame. The search is adaptively switched depending on whether the group of cells belongs to the still range or to the moving range. Using this technique, the degrees of spatial and time redundancy are reduced. This method is simulated to prove its validity. © 1999 Scripta Technica, Electron Comm Jpn Pt 1, 82(8): 32–41, 1999 [ABSTRACT FROM AUTHOR]

The era of big data introduces both opportunities and challenges for biomedical researchers. One of the inherent difficulties in the biomedical research field is to recruit large cohorts of samples, while high-throughput biotechnologies may produce thousands or even millions of features for each sample. Researchers tend to evaluate the individual correlation of each feature with the class label and use the incremental feature selection (IFS) strategy to select the top-ranked features with the best prediction performance. Recent experimental data showed that a subset of continuously ranked features randomly restarted from a low-ranked feature (an RIFS block) may outperform the subset of top-ranked features. This study proposed a feature selection Algorithm RIFS2D by integrating multiple RIFS blocks. A comprehensive comparative experiment was conducted with the IFS, RIFS and existing feature selection algorithms and demonstrated that a subset of low-ranked features may also achieve promising prediction performance. This study suggested that a prediction model with promising performance may be trained by low-ranked features, even when top-ranked features did not achieve satisfying prediction performance. Further comparative experiments were conducted between RIFS2D and t-tests for the detection of early-stage breast cancer. The data showed that the RIFS2D-recommended features achieved better prediction accuracy and were targeted by more drugs than the t-test top-ranked features., (Copyright © 2021 Elsevier Ltd. All rights reserved.)

A reusable and straightforward aptasensor with the implementation of open-ended porous silicon (OEPSi) membranes was introduced for thrombin detection. When passing through the nanochannels of OEPSi integrated in a microfluidic cell, thrombin in sample solution could be captured by thrombin-binding aptamers (TBA) immobilized along the inner walls. The formation of thrombin-aptamer complex causes refractive index changes which can be measured by reflective interferometric Fourier transform spectroscopy (RIFTS). And this flow-through configuration with OEPSi has proven more efficient in capturing thrombin than the flow-over configuration with closed-ended PSi. For higher sensitivity, we investigated how the pore size, ionic strength, pH and aptamers affected the thrombin-aptamer interaction in nanopores. Under optimized conditions, the limits of detection (LOD) for thrombin detection in the buffer and serum were ∼6.70 nM and ∼8.21 nM respectively and a wide linear detection range (10–1000 nM) was observed. More importantly, this work reveals the sensitivity of the label-free biosensor can be significantly improved by attaching newly designed aptamers with two thrombin-binding sites. This phenomenon also indicates the potential of aptamer probes in adjusting effective pore size and enhancing the interaction between aptamers and targets through meticulous sequence design. Furthermore, the proposed strategy has been applied in thrombin detection in clinic samples successfully, which was verified by Enzyme-Linked Immunosorbent Assays (ELISA). • An optical aptasensor incorporated with OEPSi for thrombin detection was proposed. • Flow-through configuration of the sensor sped up sensing and improved performance. • Thrombin detection in clinic samples was realized with LOD down to nanomolar scale. • Adjusting the aptamer sequence enhanced the sensitivity of the biosensor remarkably. [ABSTRACT FROM AUTHOR]

Aptamer biosensors are one of the most powerful techniques in biosensing. Achieving the best platform to use in aptamer biosensors typically includes crucial chemical modifications that enable aptamer immobilization on the surface in the most efficient manner. These chemical modifications must be well defined. In this work we propose nanoporous anodic alumina (NAA) chemically modified with streptavidin as a platform for aptamer immobilization. The immobilization of biotinylated thrombin binding aptamer (TBA) was monitored in real time by means of reflective interferometric spectroscopy (RIfS). The study has permitted to characterize in real time the path to immobilize TBA on the inner pore walls of NAA. Furthermore, this study provides an accurate label-free method to detect thrombin in real-time with high affinity and specificity. [ABSTRACT FROM AUTHOR]

The chemical modification, or functionalization, of the surfaces of nanomaterials is a key step to achieve biosensors with the best sensitivity and selectivity. The surface modification of biosensors usually comprises several modification steps that have to be optimized. Real-time monitoring of all the reactions taking place during such modification steps can be a highly helpful tool for optimization. In this work, we propose nanoporous anodic alumina (NAA) functionalized with the streptavidin-biotin complex as a platform towards label-free biosensors. Using reflective interferometric spectroscopy (RIfS), the streptavidin-biotin complex formation, using biotinylated thrombin as a molecule model, was monitored in real-time. The study compared the performance of different NAA pore sizes in order to achieve the highest response. Furthermore, the optimal streptavidin concentration that enabled the efficient detection of the biotinylated thrombin attachment was estimated. Finally, the ability of the NAA-RIfS system to quantify the concentration of biotinylated thrombin was evaluated. This study provides an optimized characterization method to monitor the chemical reactions that take place during the biotinylated molecules attachment within the NAA pores. [ABSTRACT FROM AUTHOR]

Membrane fluidity is a key parameter of bacterial membranes that undergoes quick adaptation in response to environmental challenges and has recently emerged as an important factor in the antibacterial mechanism of membrane-targeting antibiotics. The specific level of membrane fluidity is not uniform across the bacterial cell membrane. Rather, specialized microdomains associated with different cellular functions can exhibit fluidity values that significantly deviate from the average. Assessing changes in the overall membrane fluidity and formation of membrane microdomains is therefore pivotal to understand both the functional organization of the bacterial cell membrane as well as antibiotic mechanisms. Here we describe how two fluorescent membrane dyes, laurdan and DiIC12, can be employed to assess membrane fluidity in living bacteria. We focus on Bacillus subtilis , since this organism has been relatively well-studied with respect to membrane domains. However, we also describe how these assays can be adapted for other bacteria such as Staphylococcus aureus and Streptococcus pneumoniae ., Competing Interests: Competing interestsThe authors declare that they have no conflict of interest or competing interest., (Copyright © 2018 The Authors; exclusive licensee Bio-protocol LLC.)