MATLAB in electrochemistry: A review

Evaluation of the accuracy of new modalities in the assessment and classification of lumbar lordosis: A comparison to Cobb's angle measurement

Background

Because of the association of lumbar lordosis with some clinical conditions such as low back pain, the chiropractic field has emphasized the significance of evaluating the lumbar lordotic status, by measuring Cobb's angle, regarded as the radiological gold standard, for the assessment of lumbar lordosis, on lateral radiographs. However, research has shown that this technique has some considerable drawbacks, mostly in terms of low accuracy and high variability between clinicians when compared with other radiological modalities. The main objective was to compare the diagnostic accuracy of newly established radiological measurements with one of Cobb's angle methods, for the characterization of lumbar lordosis status in a sample of Lebanese patients aged 15 and above.

Material and methods

This retrospective single-center study consisted of measuring Cobb's L1-S1 and Cobb's L1-L5 angles, along with the novel established measurements which are the derivative and the normalized surface area, on 134 lateral radiographs of the lumbar spine of Lebanese patients aged fifteen years old and above, gotten from the Radiology department at Zahra'a's Hospital in Beirut, performed by two observers using MATLAB. Inter-rater agreement was assessed by calculating the Intra-class correlation coefficients. Spearman correlation was analyzed between both Cobb's angle methods and with the derivative and normalized area respectively. 54 patients of the sample were diagnosed by two radiologists, according to their LL status. ROC curve analysis was performed to compare the diagnostic accuracy of the four techniques used. Data were analyzed with IBM SPSS Statistics 23.0 (NY, USA); P < 0.05 was considered statistically significant.

Results

According to the ROC curve analysis the new methods, which are the derivative and the normalized surface area, displayed lower diagnostic accuracy (AUCderivative = 0.818 and 0.677, AUCsurface area = 0.796 and 0.828) than Cobb's L1-L5 (AUCL1-L5 = 0.924 and 0.929 values) and L1-S1 (AUCL1-S1 = 0.971 and 0.955) angles, in the characterization of hypo and hyperlordotic patients, respectively, in our Lebanese sample consisting of patients aged 15 and above, because of their lower area under the curve's values compared to the traditional Cobb's techniques. The Cobb's L1-S1 has shown to have the highest diagnostic accuracy among the four methods to characterize normal patients from hypo and hyperlordotic ones, by referring to its highest area under the curve's values. However, the sensitivity of Cobb's L1-L5 angle in characterizing hyperlordotic patients was similar to the one of the normalized surface area with a value of 100%.Conclusion: among the four modalities, the new methods didn't show a better diagnostic accuracy compared to the traditional modalities. Cobb's L1-S1 displayed the highest diagnostic accuracy despite its drawbacks. Further prospective studies are needed to validate the cut-offs obtained for Cobb's L1-S1 angle in our sample.

Ultrasensitive biosensing of thiram based on detection of the DNA damage induced by thiram: Application to investigation of protective effects of extra virgin olive oil against DNA damage

In this work, a novel electrochemical biosensor was fabricated based on modification of a glassy carbon electrode (GCE) with nafion-DNA/gold nanoparticles/poly-ethylenedioxy pyrrole/multi-walled carbon nanotubes-ionic liquid (NF-DNA/Au NPs/PEDOP/MWCNTs-IL/GCE) with the aim of amperometric detection of the DNA damage induced by thiram (TH). By incubation of the biosensor with the TH, the TH was intercalated within DNA, and the exposed DNA released negative charges at the surface of the biosensor which repelled the probe molecules and caused the amperometric response of the biosensor to be decreased. Protective effects of extra virgin olive oil (EVOO) on the DNA damage induced by the TH were investigated by recording amperometric responses of the biosensor in the presence of EVOO, and the results confirmed that the response of the biosensor didn't change to confirm the protective effects of the EVOO on preventing the DNA damage induced by the TH. A novel and sensitive electroanalytical method was developed for determination of the TH in two linear ranges including 1-6 pM and 7-10 pM based on amperometric detection of the DNA damage induced by the TH which gave a LOD of 0.31 pM. The developed methodology in this work was successful in detection of the DNA damage induced by TH, detection of protective effects of EVOO on preventing DNA damage and determination of the TH in real matrices.

Chemometrics-assisted electrochemical biosensing of cholesterol as the sole precursor of steroids by a novel electrochemical biosensor

This project was performed with the aims of increasing the sensitivity of differential pulse voltammetry (DPV) which itself is a sensitive electroanalytical technique, and also to compare the area under peak (univariate calibration), height of peak (univariate calibration) and whole of vector (multivariate calibration) for calibration purposes. These topics were investigated by fabrication of a novel electrochemical biosensor for determination of cholesterol (CHO). The procedure used in this project was based on the synthesis of molecularly imprinted polymers (MIPs) to the preconcentration of CHO and its biosensing by a rotating glassy carbon electrode (GCE) modified by co-immobilization of cholesterol oxidase (CO), cholesterol esterase (CE) and horseradish peroxidase (HP) onto multiwalled carbon nanotubes-ionic liquid (COCEHP/MWCNTs-IL/GCE). The results showed that the hydrodynamic DPV (HYDPV) was much more sensitive than DPV and using the area under peak for univariate calibration purposes was more suitable than height of peak. Adsorption at the electrode surface is an important trouble which affects the height and position of voltammetric peaks, but the area under peak is not affected by adsorption therefore, it can be more suitable for univariate calibration purposes. The biosensor response was also calibrated by chronoamperometry and the results confirmed that the HYDPV was more sensitive than chronoamperometry. The next attempt was based on recording the biosensor responses based on second-order HYDPV data and modeling of them (whole of vectors) by three-way calibration methods which showed the best performance among the tested methods for determination of CHO. The biosensor response was long-term stable, repeatable and reproducible which was successfully applied to the analysis of serum sample towards determination of CHO whose results were comparable with a reference method.

Sensitive and selective simultaneous biosensing of nandrolone and testosterone as two anabolic steroids by a novel biosensor assisted by second-order calibration

Recently, our research group have focused on an interesting project in which a novel dual template molecularly imprinted (DTMIP) biosensor was fabricated and assisted by second-order differential pulse voltammetric (DPV) data for simultaneous determination of nandrolone decanoate (ND) and testosterone decanoate (TS). An indium tin oxide (ITO) was modified with multiwalled carbon nanotubes-graphene-ionic liquid (MWCNT-Gr-IL) and then, the fullerene C₆₀ was casted onto the surface of MWCNT-Gr-IL/ITO and electrochemically reduced. Finally, DTMIPs were electrosynthesized by electropolymerization of 4-aminobenzoic acid (ABA) as monomer with ND and TS as template molecules to obtain the final structure of the biosensor (DTMIP/C₆₀/MWCNT-Gr-IL/ITO). Structure of the biosensor was electrochemically and microscopically characterized. The ND and TS generated two severely overlapped DPVs at the surface of the biosensor which forced us to assist the biosensor with three-way calibration by second-order DPV data to simultaneous determine them. Two second-order algorithms including multivariate curve resolution alternating least squares (MCR-ALS) and parallel factor analysis2 (PARAFAC2) were used to build second-order calibration models and evaluation of their performance in the analysis of synthetic samples showed more superiority of the MCR-ALS than PARAFC2 which motivated us to select PARAFC2 for the analysis of urine samples as real cases. Application of the biosensor assisted by PARAFC2 for the analysis of urine samples towards simultaneous determination of ND and TS was successful.

Resolving interactions of miglitol with normal and glycated human serum albumin by multivariate methods

This article reports results of one of our projects related to the investigation of interactions of miglitol (MIG) with normal human serum albumin (HSA) and glycated HSA (GHSA) with the help of recording spectroscopic and electrochemical data. The experimental data were analyzed by conventional and chemometric methods to extract useful information for comprehensive justifications of the interactions of the MIG with HSA and GHSA. Hard- and soft-modeling chemometric methods were used to extract quantitative and qualitative information. Then, molecular docking techniques were used to further investigation of the binding of the MIG with HSA and GHSA and the extracted results were compatible with those obtained by experimental methods. Finally, according to the binding of the BV with HSA and GHSA, second-order differential pulse voltammetric data were recorded and calibrated with three-way calibration methods for exploiting second-order advantage for determination of the GHSA in the presence of the HSA to develop a novel chemometrics assisted-electroanalytical method for diagnostic and monitoring of diabetic.

Chemometric modeling of the electrochemical data to investigate proline cis/trans isomeration effect on aggregation of Tau protein

Tau protein (Tau) is a proline-rich protein and in this work, we have developed a very interesting strategy based on combination of electrochemistry with chemometric methods to investigate proline cis/trans isomeration effect on the Tau aggregation. To achieve this goal, the proline residues at RTPPK motif have been replaced by alanine to generate RTPAK, RTAPK and RTAAK mutants of the Tau. Then, cyclic voltammetric (CV) responses of the Tau and RTPAK, RTAPK and RTAAK as its mutants in the presence of heparin (HEP) as an anionic inducing agent which could trigger aggregation of the Tau were recorded at physiological conditions every hour during 12 h. Therefore, 48 data sets of titrations were obtained which were handled by chemometric methods to extract useful information about aggregation of the Tau. The data were hard-modeled by EQUISPEC, SQUAD, REACTLAB and SPECFIT to extract useful quantitative information. Our results confirmed that the strength of the binding of the HEP with proteins was obeyed from Tau > RTPAK ~ RTAPK > RTAAK which confirmed that the aggregation of the proteins was obeyed from this order as well. Therefore, aggregation of the Tau is decreased by transforming Cis isomer to Trans even in the presence of an anionic inducing agent such as HEP which may have value for the treatment of Alzheimer's disease.

Application of Mathematical Models and Microfluidics in the Analysis of Saliva Mixing with Antiseptic Solutions

Background/Aim: Human saliva offers many advantages over blood-based biochemical assays, therefore, becomes the biological fluid of interest. Once antiseptic solutions react with saliva, both fluids undergo significant changes of their biophysical properties, consequently, those changes have an impact on their principal function.

Material and Methods: In this study, saliva was collected and mixed with 0,1% chlorhexidine digluconate solution, fluoride mouthwash, zinc-hydroxyapatite solution and CPP-ACP paste. Microfluidic PVC/Green tape chips within the experimental setup were used to simulate solution mixing. The chip had 2 inlets and 1 outlet, and channel was designed in Y shape without any obstacles. The inlet channels were set at a 60° angle. The channel width was 600 µm and the diameter of inlets and outlet was 2 mm. For better visualization, blue food coloring was added to the saliva. The procedure was recorded with digital USB microscope camera and afterwards the percentage of mixing was obtained by MATLAB programming language.

Results: Obtained results show incomplete mixing of all the solutions with saliva. The value of mixed liquid, when mixing 0,1% chlorhexidine digluconate solution with saliva was 51,11%. In case of medium concentration fluoride mouthwash, result was 84,37%. Zinc hydroxyapatite solution obtained result of 85,24%, and the fourth tested solution, CPP-ACP paste, 83,89%.

Conclusions: Analyzed mouthwashes exhibit specific, non uniform behavior during mixing with saliva. Microfluidic setups could be efficiently used in simulating real clinical conditions in laboratory settings. Image processing mathematical models are applicable, accurate and useful in determination of the interaction of saliva with commonly used antiseptic solutions.

Processing Fluorescence Spectra for Pollutants Detection Systems in Inland Waters

Development of contaminant detection systems in various natural and industrial environments has been favored in recent years thanks to the evolution of processors and sensors. Our group works specifically on contaminant detection systems in inland waters: immediate and continuous detection is a fundamental requirement in this type of sensing. Regarding the sensors, the proposed system is based on fluorescence, since it offers a method in which there is no contact with water, which means less wear on the components and a great saving in cleaning and maintenance. On the other hand, the spectrum processing is of great importance, since it is used both in the generation of a library of fluorescence spectra taken in the laboratory and in the continuous analysis of the samples and in the comparison algorithm for identification. The validity of the system is based on the last process that is carried out in a very short time. This article describes a system to process spectra in a more accelerated way.

Simultaneous imaging of latent fingerprint and quantification of nicotine residue by NaYF4:Yb/Tm upconversion nanoparticles

Numerous investigations have been devoted to visualizing latent fingerprints (LFPs) for personal identification in forensic investigation and age estimation. While simultaneous detection of chemicals in fingerprint residues has yet to be explored. Herein, fluorescent NaYF₄:Yb/Tm up-conversion nanoparticles (UCNPs), which can emit blue fluorescence upon 980 nm near-infrared irradiation, have been employed in the imaging of LFPs with high contrast and high sensitivity. The furrows and ridges which provide detailed information of LFP have been displayed clearly by Tm-doped UCNPs. Meanwhile, the quantitation of nicotine residue in LFPs has been achieved based on the blue fluorescence absorbed by I₂-nicotine complex, and the data was analyzed by MATLAB with modified OPTA algorithm. It was proved that the established strategy was specific, sensitive, reliable and practical toward nicotine residue in LFPs with a detection limit of 0.05 μg.

An elegant technology for ultrasensitive impedimetric and voltammetric determination of cholestanol based on a novel molecularly imprinted electrochemical sensor

In this work, a novel molecularly imprinted electrochemical sensor (MIES) has been fabricated based on electropolymerization of a molecularly imprinted polymer (MIP) onto a glassy carbon electrode (GCE) modified with gold-palladium alloy nanoparticles (AuPd NPs)/polydopamine film (PDA)/multiwalled carbon nanotubes-chitosan-ionic liquid (MWCNTs-CS-IL) for voltammetric and impedimetric determination of cholestanol (CHO). Modifications applied to the bare GCE formed an excellent biocompatible composite film which was able to selectively detect CHO molecules. Modifications applied to the bare GCE were characterized by scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (SEM). Under optimal experimental conditions, the sensor was able to detect CHO in the range of 0.1-60 pM and 1-50 pM by EIS and DPV, respectively. Moreover, the sensor showed high sensitivity, selectivity, repeatability, reproducibility, low interference and good stability towards CHO determination. Our records confirmed that the sensor was successfully able to the analysis real samples for determination of CHO.

Coupling of digital image processing and three-way calibration to assist a paper-based sensor for determination of nitrite in food samples

In this work, a novel and very interesting analytical methodology based on coupling of digital image processing and three-way calibration has been developed for determination of nitrite in food samples.

Capital Structure of Public–Private Partnership Projects: A Sustainability Perspective

Capital is key to achieve the standardized operation of public–private partnership (PPP) projects. The capital structure of PPP projects stresses the structure of equity and debt funds, which are important for securing life-cycle ample funds and achieving the expected outcomes of projects. By incorporating sustainability into PPP projects, the capital structure not only secures current needs of funds, it also focuses on life-cycle stable operations and achieves economic, social, and environmental benefits. This study first set the equity–debt ratio and equity investment ratio of the private sector as the dependent variables and built a selection model of the capital structure of PPP projects from a sustainability perspective using the benefit, cost, and project conditions as core factors based on multi-objective programming and a discounted cash-flow model. Then, the qualitative analysis could be achieved according to the analysis of critical factors that had not been calculated. Afterwards, a selection process which combined the multi-objective programming model with qualitative analysis was proposed to achieve a comprehensive selection of the capital structure of PPP projects from the sustainability perspective. Finally, the process was applied to a real project to verify its rationality and usability. This study not only enriches the theoretical research of PPP projects and provides a new idea on which to build the capital structure selection model, it also proposes a selection process that can provide scientific references for the selection and optimization of the capital structure of PPP projects in practice.

Fabrication of a novel impedimetric biosensor for label free detection of DNA damage induced by doxorubicin

In this work, a novel impedimetric biosensor has been fabricated for detection of DNA damage induced by doxorubicin (DX). Cytochrome P450 reductase (CPR) is required for electron transfer from nicotinamide adenine dinucleotide phosphate (NADPH) to cytochrome P450 (CP450) which causes DX to undergo a one-electron reduction of the p-quinone residue to form the semiquinone radical resulting in the generation of free hydroxyl radical which causes DNA damage. After modification of bare glassy carbon electrode (GCE) with multiwalled carbon nanotubes (MWCNTs) and chitosan (Ch), CPR and CP450 were co-immobilized onto the surface of Ch/MWCNTs/GCE by cross-linking CPR, CP450 and Ch through addition of glutaraldehyde. Then, the DNA was assembled onto the surface of CPRCP450/Ch/MWCNTs/GCE to fabricate the biosensor (DNA/CPRCP450/Ch/MWCNTs/GCE). Modifications applied to the bare GCE to fabricate the biosensor were characterized by CV, EIS and SEM. The DNA/CPRCP450/Ch/MWCNTs/GCE was treated in the damaging solution (DX + NADPH) which caused a significant DNA damage and the exposed DNA bases reduced the electrostatic repulsion of the negatively charged redox probe leading to Faradaic impedance changes. Performance of the biosensor for detection of DNA damage in the presence of Spinach extract was also examined and finally, an indirect impedimetric method was developed for determination of DX.