Displaying publications 41 - 60 of 365 in total

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  1. Fulltext Simultaneous electrochemical detection of dopamine and ascorbic acid using an iron oxide/reduced graphene oxide modified glassy carbon electrode
    Peik-See T, Pandikumar A, Nay-Ming H, Hong-Ngee L, Sulaiman Y
    Sensors (Basel), 2014;14(8):15227-43.
    PMID: 25195850 DOI: 10.3390/s140815227
    The fabrication of an electrochemical sensor based on an iron oxide/graphene modified glassy carbon electrode (Fe3O4/rGO/GCE) and its simultaneous detection of dopamine (DA) and ascorbic acid (AA) is described here. The Fe3O4/rGO nanocomposite was synthesized via a simple, one step in-situ wet chemical method and characterized by different techniques. The presence of Fe3O4 nanoparticles on the surface of rGO sheets was confirmed by FESEM and TEM images. The electrochemical behavior of Fe3O4/rGO/GCE towards electrocatalytic oxidation of DA was investigated by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) analysis. The electrochemical studies revealed that the Fe3O4/rGO/GCE dramatically increased the current response against the DA, due to the synergistic effect emerged between Fe3O4 and rGO. This implies that Fe3O4/rGO/GCE could exhibit excellent electrocatalytic activity and remarkable electron transfer kinetics towards the oxidation of DA. Moreover, the modified sensor electrode portrayed sensitivity and selectivity for simultaneous determination of AA and DA. The observed DPVs response linearly depends on AA and DA concentration in the range of 1-9 mM and 0.5-100 µM, with correlation coefficients of 0.995 and 0.996, respectively. The detection limit of (S/N = 3) was found to be 0.42 and 0.12 µM for AA and DA, respectively.
    Matched MeSH terms: Biosensing Techniques/methods*
  2. Simultaneous determination of ascorbic acid, dopamine and uric acid by a novel electrochemical sensor based on N2/Ar RF plasma assisted graphene nanosheets/graphene nanoribbons
    Jothi L, Neogi S, Jaganathan SK, Nageswaran G
    Biosens Bioelectron, 2018 May 15;105:236-242.
    PMID: 29412948 DOI: 10.1016/j.bios.2018.01.040
    A novel nitrogen/argon (N2/Ar) radio frequency (RF) plasma functionalized graphene nanosheet/graphene nanoribbon (GS/GNR) hybrid material (N2/Ar/GS/GNR) was developed for simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA). Various nitrogen mites introduced into GS/GNR hybrid structure was evidenced by a detailed microscopic, spectroscopic and surface area analysis. Owing to the unique structure and properties originating from the enhanced surface area, nitrogen functional groups and defects introduced on both the basal and edges, N2/Ar/GS/GNR/GCE showed high electrocatalytic activity for the electrochemical oxidations of AA, DA, and UA with the respective lowest detection limits of 5.3, 2.5 and 5.7 nM and peak-to-peak separation potential (ΔEP) (vs Ag/AgCl) in DPV of 220, 152 and 372 mV for AA/DA, DA/UA and AA/UA respectively. Moreover, the selectivity, stability, repeatability and excellent performance in real time application of the fabricated N2/Ar/GS/GNR/GCE electrode suggests that it can be considered as a potential electrode material for simultaneous detection of AA, DA, and UA.
    Matched MeSH terms: Biosensing Techniques/methods*
  3. Silver nanoparticles decorated polyaniline nanocomposite based electrochemical sensor for the determination of anticancer drug 5-fluorouracil
    Zahed FM, Hatamluyi B, Lorestani F, Es'haghi Z
    J Pharm Biomed Anal, 2018 Nov 30;161:12-19.
    PMID: 30142492 DOI: 10.1016/j.jpba.2018.08.004
    A highly efficient electrochemical sensor for the analysis of anticancer drug 5-fluorouracil (5-FU), is fabricated based on silver nanoparticles-polyaniline nanotube (AgNPs@PANINTs). AgNPs@PANINTs nanocomposite has been synthesized by a simple one-step method. Synthesized AgNPs@PANINTs nanocomposite was studied by Fourier transform infrared spectrometry, Scanning Electron Microscopy and Energy Dispersive X-ray. The fabricated PANINTs@AgNPs PGE was applied to the electrochemical sensing of 5-FU. Cyclic voltammetry and differential pulse voltammetry experiments illustrated high electro activity for the AgNPs@PANINTs nanocomposite. The study was explored using the Taguchi experimental design method. Electrochemical measurements using differential pulse voltammetry showed a wide linear relationship between 5-FU concentration and peak height within the range 1.0-300.0 μM with a low detection limit (0.06 μM). Also, the fabricated sensor showed excellent selectivity in the presence of two anticancer drugs and a number of other interfering compounds. The as-prepared sensor showed to be a promising device for a simple, rapid, and direct analysis of 5-FU.
    Matched MeSH terms: Biosensing Techniques/methods*
  4. Fulltext Silicene Quantum Capacitance Dependent Frequency Readout to a Label-Free Detection of DNA Hybridization- A Simulation Analysis
    Rahman MS, Naima RL, Shetu KJ, Hossain MM, Kaiser MS, Hosen ASMS, et al.
    Biosensors (Basel), 2021 Jun 01;11(6).
    PMID: 34205927 DOI: 10.3390/bios11060178
    The use of deoxyribonucleic acid (DNA) hybridization to detect disease-related gene expression is a valuable diagnostic tool. An ion-sensitive field-effect transistor (ISFET) with a graphene layer has been utilized for detecting DNA hybridization. Silicene is a two-dimensional silicon allotrope with structural properties similar to graphene. Thus, it has recently experienced intensive scientific research interest due to its unique electrical, mechanical, and sensing characteristics. In this paper, we proposed an ISFET structure with silicene and electrolyte layers for the label-free detection of DNA hybridization. When DNA hybridization occurs, it changes the ion concentration in the surface layer of the silicene and the pH level of the electrolyte solution. The process also changes the quantum capacitance of the silicene layer and the electrical properties of the ISFET device. The quantum capacitance and the corresponding resonant frequency readout of the silicene and graphene are compared. The performance evaluation found that the changes in quantum capacitance, resonant frequency, and tuning ratio indicate that the sensitivity of silicene is much more effective than graphene.
    Matched MeSH terms: Biosensing Techniques
  5. Signal Enhancement Strategies for Refractive Index-Sensitive Nanobiosensor
    Syahir A, Kajikawa K, Mihara H
    Protein Pept Lett, 2018;25(1):34-41.
    PMID: 29237369 DOI: 10.2174/0929866525666171214111957
    BACKGROUND: Direct bio-monitoring essentially involves optical means since photon has insignificant effects over biomolecules. Over the years, laser induced surface Plasmon resonance method with various modifications as well as versatile localized Plasmon excited by incoherent light have facilitated in recording many nanobiological activities. Yet, monitoring interactions of small molecules including drugs requires signal amplification and improvement on signal-to-noise ratio.

    OBJECTIVES: This paper focused on how the refractive index based nanobio-sensoring gold platform can produce more efficient, adaptable and more practical detection techniques to observe molecular interactions at high degree of sensitivity. It discusses surface chemistry approach, optimisation of the refractive index of gold platform and manipulation of gold geometry augmenting signal quality.

    METHODS: In a normal-incidence reflectivity, r0 can be calculated using the Fresnel equation. Particularly at λ = 470 nm the ratio of r / r0 showed significant amplitude reduction mainly stemmed from the imaginary part of the Au refractive index. Hence, the fraction of reduction, Δr = 1 - r / r0. Experimentally, in a common reference frame reflectivity of a bare gold surface, R0 is compared with the reflectivity of gold surface in the presence of biolayer, R. The reduction rate (%) of reflectivity, ΔR = 1 - R / R0 is denoted as the AR signal. The method therefore enables quantitative measurement of the surface-bound protein by converting ΔR to the thickness, d, and subsequently the protein mass. We discussed four strategies to improve the AR signal by changing the effective refractive index of the biosensing platform. They are; a) Thickness optimisation of Au thin layer, b) Au / Ag bimetallic layer, c) composing alloy or Au composite, and d) Au thinlayer with nano or micro holes.

    RESULTS: As the result we successfully 'move' the refractive index, ε of the AR platform (gold only) to ε = -0.948 + 3.455i, a higher sensitivity platform. This was done by composing Au-Ag2O composite with ratio = 1:1. The results were compared to the potential sensitivity improvement of the AR substrate using other that could be done by further tailoring the ε advanced method.

    CONCLUSION: We suggested four strategies in order to realize this purpose. It is apparent that sensitivity has been improved through Au/Ag bimetallic layer or Au-Ag2O composite thin layer, This study is an important step towards fabrication of sensitive surface for detection of biomolecular interactions.

    Matched MeSH terms: Biosensing Techniques
  6. Fulltext Short chain N-acyl homoserine lactone production by soil isolate Burkholderia sp. strain A9
    Chen JW, Koh CL, Sam CK, Yin WF, Chan KG
    Sensors (Basel), 2013;13(10):13217-27.
    PMID: 24084115 DOI: 10.3390/s131013217
    In the bacteria kingdom, quorum sensing (QS) is a cell-to-cell communication that relies on the production of and response to specific signaling molecules. In proteobacteria, N-acylhomoserine lactones (AHLs) are the well-studied signaling molecules. The present study aimed to characterize the production of AHL of a bacterial strain A9 isolated from a Malaysian tropical soil. Strain A9 was identified as Burkholderia sp. using matrix-assisted laser desorption ionization-time-of-flight mass spectrometry and 16S rDNA nucleotide sequence analysis. AHL production by A9 was detected with two biosensors, namely Chromobacterium violaceum CV026 and Escherichia coli [pSB401]. Thin layer chromatography results showed N-hexanoylhomoserine lactone (C6-HSL) and N-octanoylhomoserine lactone (C8-HSL) production. Unequivocal identification of C6-HSL and C8-HSL was achieved by high resolution triple quadrupole liquid chromatography-mass spectrometry analysis. We have demonstrated that Burkholderia sp. strain A9 produces AHLs that are known to be produced by other Burkholderia spp. with CepI/CepR homologs.
    Matched MeSH terms: Biosensing Techniques/methods*
  7. Serological diagnosis of dengue infection in blood plasma using long-range surface plasmon waveguides
    Wong WR, Krupin O, Sekaran SD, Mahamd Adikan FR, Berini P
    Anal Chem, 2014 Feb 4;86(3):1735-43.
    PMID: 24410440 DOI: 10.1021/ac403539k
    We present a compact, cost-effective, label-free, real-time biosensor based on long-range surface plasmon polariton (LRSPP) gold (Au) waveguides for the detection of dengue-specific immunoglobulin M (IgM) antibody, and we demonstrate detection in actual patient blood plasma samples. Two surface functionalization approaches are proposed and demonstrated: a dengue virus serotype 2 (DENV-2) functionalized surface to capture dengue-specific IgM antibody in blood plasma and the reverse, a blood plasma functionalized surface to capture DENV-2. The results obtained via these two surface functionalization approaches are comparable to, or of greater quality, than those collected by conventional IgM antibody capture enzyme linked immunosorbent assay (MAC-ELISA). Our second functionalization approach was found to minimize nonspecific binding, thus improving the sensitivity and accuracy of the test. We also demonstrate reuse of the biosensors by regenerating the sensing surface down to the virus (or antibody) level or down to the bare Au.
    Matched MeSH terms: Biosensing Techniques/economics; Biosensing Techniques/methods*
  8. Fulltext Sequential push-pull pumping mechanism for washing and evacuation of an immunoassay reaction chamber on a microfluidic CD platform
    Thio TH, Ibrahim F, Al-Faqheri W, Soin N, Kahar Bador M, Madou M
    PLoS One, 2015;10(4):e0121836.
    PMID: 25853411 DOI: 10.1371/journal.pone.0121836
    A centrifugal compact disc (CD) microfluidic platform with reservoirs, micro-channels, and valves can be employed for implementing a complete immunoassay. Detection or biosensor chambers are either coated for immuno-interaction or a biosensor chip is inserted in them. On microfluidic CDs featuring such multi-step chemical/biological processes, the biosensor chamber must be repeatedly filled with fluids such as enzymes solutions, buffers, and washing solutions. After each filling step, the biosensor chamber needs to be evacuated by a passive siphoning process to prepare it for the next step in the assay. However, rotational speed dependency and limited space on a CD are two big obstacles to performing such repetitive filling and siphoning steps. In this work, a unique thermo-pneumatic (TP) Push-Pull pumping method is employed to provide a superior alternative biosensor chamber filling and evacuation technique. The proposed technique is demonstrated on two CD designs. The first design features a simple two-step microfluidic process to demonstrate the evacuation technique, while the second design shows the filling and evacuation technique with an example sequence for an actual immunoassay. In addition, the performance of the filling and evacuation technique as a washing step is also evaluated quantitatively and compared to the conventional manual bench top washing method. The two designs and the performance evaluation demonstrate that the technique is simple to implement, reliable, easy to control, and allows for repeated push-pulls and thus filling and emptying of the biosensor chamber. Furthermore, by addressing the issue of rotational speed dependency and limited space concerns in implementing repetitive filling and evacuation steps, this newly introduced technique increases the flexibility of the microfluidic CD platform to perform multi-step biological and chemical processes.
    Matched MeSH terms: Biosensing Techniques/instrumentation*
  9. Sensitivity enhancement of urea biosensor based on surface plasmon resonance and kretschmann configuration with graphene-mos2 hybrid structure
    Nur Akmar Jamil, Gan SM, Burhanuddin Yeop Majlis, Susthitha Menon P
    Sains Malaysiana, 2018;47:1033-1038.
    Artikel ini menganalisis biosensor resonans plasmon permukaan (SPR) dengan lapisan grafin yang meningkatkan
    kecekapan biosensor urea kerana penerapannya yang tinggi. Tatasusunan Kretschmann merupakan teknik yang paling
    berkesan digunakan untuk pengujaan plasmon. Dalam kajian ini, kami menganalisis kesan ekalapisan MoS2 dengan
    lapisan grafin yang didepositkan pada bahan plasmon, iaitu logam emas (Au), di dalam tatasusunan ini. Simulasi untuk
    menganalisis tatasusunan ini adalah berdasarkan kepada kaedah perbezaan terhingga domain masa (FDTD). Prestasi
    biosensor SPR dapat dipantau dengan menganalisis kepekaan dan lebar penuh pada separuh maksimum (FWHM) spektrum
    SPR. Pengukuran diperhatikan pada panjang gelombang 670 nm dan 785 nm untuk pengesanan urea. Indeks molar dan
    indeks biasan berbeza (RI) daripada 1.335 sehingga 1.342 untuk lapisan penderiaan. Keputusan menunjukkan peratus
    peningkatan kepekaan biosensor Au/MoS2
    /grafin berbanding biosensor Au konvensional adalah 98% dan 202% masingmasing
    pada panjang gelombang 670 nm dan 785 nm. Ini menunjukkan bahawa cadangan biosensor SPR yang novel ini
    adalah lebih sensitif untuk pengesanan urea.
    Matched MeSH terms: Biosensing Techniques
  10. Sensitivity enhancement of graphene/zinc oxide nanocomposite-based electrochemical impedance genosensor for single stranded RNA detection
    Low SS, Loh HS, Boey JS, Khiew PS, Chiu WS, Tan MTT
    Biosens Bioelectron, 2017 Aug 15;94:365-373.
    PMID: 28319904 DOI: 10.1016/j.bios.2017.02.038
    An efficient electrochemical impedance genosensing platform has been constructed based on graphene/zinc oxide nanocomposite produced via a facile and green approach. Highly pristine graphene was synthesised from graphite through liquid phase sonication and then mixed with zinc acetate hexahydrate for the synthesis of graphene/zinc oxide nanocomposite by solvothermal growth. The as-synthesised graphene/zinc oxide nanocomposite was characterised with scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and X-ray diffractometry (XRD) to evaluate its morphology, crystallinity, composition and purity. An amino-modified single stranded DNA oligonucleotide probe synthesised based on complementary Coconut Cadang-Cadang Viroid (CCCVd) RNA sequence, was covalently bonded onto the surface of graphene/zinc oxide nanocomposite by the bio-linker 1-pyrenebutyric acid N-hydroxysuccinimide ester. The hybridisation events were monitored by electrochemical impedance spectroscopy (EIS). Under optimised sensing conditions, the single stranded CCCVd RNA oligonucleotide target could be quantified in a wide range of 1.0×10-11M to 1.0×10-6 with good linearity (R =0.9927), high sensitivity with low detection limit of 4.3×10-12M. Differential pulse voltammetry (DPV) was also performed for the estimation of nucleic acid density on the graphene/zinc oxide nanocomposite-modified sensing platform. The current work demonstrates an important advancement towards the development of a sensitive detection assay for various diseases involving RNA agents such as CCCVd in the future.
    Matched MeSH terms: Biosensing Techniques/methods*
  11. Sensitive silica-alumina modified capacitive non-Faradaic glucose sensor for gestational diabetes
    Chen L, Xie W, Luo Y, Ding X, Fu B, Gopinath SCB, et al.
    Biotechnol Appl Biochem, 2021 Mar 30.
    PMID: 33786878 DOI: 10.1002/bab.2155
    A highly sensitive silica-alumina (Si-Al)-modified capacitive non-Faradaic glucose biosensor was introduced to monitor gestational diabetes. Glucose oxidase (GOx) was attached to the Si-Al electrode surface as the probe through amine-modification followed by glutaraldehyde premixed GOx as aldehyde-amine chemistry. This Si-Al (∼50 nm) modified electrode surface has increased the current flow upon binding of GOx with glucose. Capacitance values were increased by increasing the glucose concentrations. A mean capacitance value was plotted and the detection limit was found as 0.03 mg/mL with the regression coefficient value, R² = 0.9782 [y = 0.8391x + 1.338] on the linear range between 0.03 and 1 mg/mL. Further, a biofouling experiment with fructose and galactose did not increase the capacitance, indicating the specific glucose detection. This Si-Al-modified capacitance sensor detects a lower level of glucose presence and helps in monitoring gestational diabetes.
    Matched MeSH terms: Biosensing Techniques
  12. Sensitive Leptospira DNA detection using tapered optical fiber sensor
    Zainuddin NH, Chee HY, Ahmad MZ, Mahdi MA, Abu Bakar MH, Yaacob MH
    J Biophotonics, 2018 08;11(8):e201700363.
    PMID: 29570957 DOI: 10.1002/jbio.201700363
    This paper presents the development of tapered optical fiber sensor to detect a specific Leptospira bacteria DNA. The bacteria causes Leptospirosis, a deadly disease but with common early flu-like symptoms. Optical single mode fiber (SMF) of 125 μm diameter is tapered to produce 12 μm waist diameter and 15 cm length. The novel DNA-based optical fiber sensor is functionalized by incubating the tapered region with sodium hydroxide (NaOH), (3-Aminopropyl) triethoxysilane and glutaraldehyde. Probe DNA is immobilized onto the tapered region and subsequently hybridized by its complementary DNA (cDNA). The transmission spectra of the DNA-based optical fiber sensor are measured in the 1500 to 1600 nm wavelength range. It is discovered that the shift of the wavelength in the SMF sensor is linearly proportional with the increase in the cDNA concentrations from 0.1 to 1.0 nM. The sensitivity of the sensor toward DNA is measured to be 1.2862 nm/nM and able to detect as low as 0.1 fM. The sensor indicates high specificity when only minimal shift is detected for non-cDNA testing. The developed sensor is able to distinguish between actual DNA of Leptospira serovars (Canicola and Copenhageni) against Clostridium difficile (control sample) at very low (femtomolar) target concentrations.
    Matched MeSH terms: Biosensing Techniques/instrumentation*
  13. Sensing strategies for influenza surveillance
    Gopinath SC, Tang TH, Chen Y, Citartan M, Tominaga J, Lakshmipriya T
    Biosens Bioelectron, 2014 Nov 15;61:357-69.
    PMID: 24912036 DOI: 10.1016/j.bios.2014.05.024
    Influenza viruses, which are RNA viruses belonging to the family Orthomyxoviridae, cause respiratory diseases in birds and mammals. With seasonal epidemics, influenza spreads all over the world, resulting in pandemics that cause millions of deaths. Emergence of various types and subtypes of influenza, such as H1N1 and H7N9, requires effective surveillance to prevent their spread and to develop appropriate anti-influenza vaccines. Diagnostic probes such as glycans, aptamers, and antibodies now allow discrimination among the influenza strains, including new subtypes. Several sensors have been developed based on these probes, efforts made to augment influenza detection. Herein, we review the currently available sensing strategies to detect influenza viruses.
    Matched MeSH terms: Biosensing Techniques/instrumentation; Biosensing Techniques/methods*
  14. Fulltext Selection and characterisation of Affimers specific for CEA recognition
    Shamsuddin SH, Jayne DG, Tomlinson DC, McPherson MJ, Millner PA
    Sci Rep, 2021 01 12;11(1):744.
    PMID: 33436840 DOI: 10.1038/s41598-020-80354-6
    Carcinoembryonic antigen (CEA) is the only blood based protein biomarker at present, used for preoperative screening of advanced colorectal cancer (CRC) patients to determine the appropriate curative treatments and post-surveillance screening for tumour recurrence. Current diagnostics for CRC detection have several limitations and development of a highly sensitive, specific and rapid diagnostic device is required. The majority of such devices developed to date are antibody-based and suffer from shortcomings including multimeric binding, cost and difficulties in mass production. To circumvent antibody-derived limitations, the present study focused on the development of Affimer proteins as a novel alternative binding reagent for CEA detection. Here, we describe the selection, from a phage display library, of Affimers specific to CEA protein. Characterization of three anti-CEA Affimers reveal that these bind specifically and selectively to protein epitopes of CEA from cell culture lysate and on fixed cells. Kinetic binding analysis by SPR show that the Affimers bind to CEA with high affinity and within the nM range. Therefore, they have substantial potential for used as novel affinity reagents in diagnostic imaging, targeted CRC therapy, affinity purification and biosensor applications.
    Matched MeSH terms: Biosensing Techniques/methods*
  15. Fulltext Sandwich-Type DNA Micro-Optode Based on Gold-Latex Spheres Label for Reflectance Dengue Virus Detection
    Jeningsih, Tan LL, Ulianas A, Heng LY, Mazlan NF, Jamaluddin ND, et al.
    Sensors (Basel), 2020 Mar 25;20(7).
    PMID: 32218202 DOI: 10.3390/s20071820
    A DNA micro-optode for dengue virus detection was developed based on the sandwich hybridization strategy of DNAs on succinimide-functionalized poly(n-butyl acrylate) (poly(nBA-NAS)) microspheres. Gold nanoparticles (AuNPs) with an average diameter of ~20 nm were synthesized using a centrifugation-based method and adsorbed on the submicrometer-sized polyelectrolyte-coated poly(styrene-co-acrylic acid) (PSA) latex particles via an electrostatic method. The AuNP-latex spheres were attached to the thiolated reporter probe (rDNA) by Au-thiol binding to functionalize as an optical gold-latex-rDNA label. The one-step sandwich hybridization recognition involved a pair of a DNA probe, i.e., capture probe (pDNA), and AuNP-PSA reporter label that flanked the target DNA (complementary DNA (cDNA)). The concentration of dengue virus cDNA was optically transduced by immobilized AuNP-PSA-rDNA conjugates as the DNA micro-optode exhibited a violet hue upon the DNA sandwich hybridization reaction, which could be monitored by a fiber-optic reflectance spectrophotometer at 637 nm. The optical genosensor showed a linear reflectance response over a wide cDNA concentration range from 1.0 × 10-21 M to 1.0 × 10-12 M cDNA (R2 = 0.9807) with a limit of detection (LOD) of 1 × 10-29 M. The DNA biosensor was reusable for three consecutive applications after regeneration with mild sodium hydroxide. The sandwich-type optical biosensor was well validated with a molecular reverse transcription polymerase chain reaction (RT-PCR) technique for screening of dengue virus in clinical samples, e.g., serum, urine, and saliva from dengue virus-infected patients under informed consent.
    Matched MeSH terms: Biosensing Techniques*
  16. Fulltext Sandwich Electrochemical Immunosensor for Early Detection of Tuberculosis Based on Graphene/Polyaniline-Modified Screen-Printed Gold Electrode
    Mohd Azmi UZ, Yusof NA, Kusnin N, Abdullah J, Suraiya S, Ong PS, et al.
    Sensors (Basel), 2018 Nov 14;18(11).
    PMID: 30441776 DOI: 10.3390/s18113926
    A rapid and sensitive sandwich electrochemical immunosensor was developed based on the fabrication of the graphene/polyaniline (GP/PANI) nanocomposite onto screen-printed gold electrode (SPGE) for detection of tuberculosis biomarker 10-kDa culture filtrate protein (CFP10). The prepared GP/PANI nanocomposite was characterized using Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). The chemical bonding and morphology of GP/PANI-modified SPGE were studied by Raman spectroscopy and FESEM coupled with energy dispersive X-ray spectroscopy, respectively. From both studies, it clearly showed that GP/PANI was successfully coated onto SPGE through drop cast technique. Cyclic voltammetry was used to study the electrochemical properties of the modified electrode. The effective surface area for GP/PANI-modified SPGE was enhanced about five times compared with bare SPGE. Differential pulse voltammetry was used to detect the CFP10 antigen. The GP/PANI-modified SPGE that was fortified with sandwich type immunosensor exhibited a wide linear range (20⁻100 ng/mL) with a low detection limit of 15 ng/mL. This proposed electrochemical immunosensor is sensitive, low sample volume, rapid and disposable, which is suitable for tuberculosis detection in real samples.
    Matched MeSH terms: Biosensing Techniques*
  17. Fulltext Saliva-based biosensors: noninvasive monitoring tool for clinical diagnostics
    Malon RS, Sadir S, Balakrishnan M, Córcoles EP
    Biomed Res Int, 2014;2014:962903.
    PMID: 25276835 DOI: 10.1155/2014/962903
    Saliva is increasingly recognised as an attractive diagnostic fluid. The presence of various disease signalling salivary biomarkers that accurately reflect normal and disease states in humans and the sampling benefits compared to blood sampling are some of the reasons for this recognition. This explains the burgeoning research field in assay developments and technological advancements for the detection of various salivary biomarkers to improve clinical diagnosis, management, and treatment. This paper reviews the significance of salivary biomarkers for clinical diagnosis and therapeutic applications, with focus on the technologies and biosensing platforms that have been reported for screening these biomarkers.
    Matched MeSH terms: Biosensing Techniques/methods*
  18. Reflectance aptasensor based on metal salphen label for rapid and facile determination of insulin
    Taib M, Tan LL, Abd Karim NH, Ta GC, Heng LY, Khalid B
    Talanta, 2020 Jan 15;207:120321.
    PMID: 31594568 DOI: 10.1016/j.talanta.2019.120321
    An optical aptasensor-based sensing platform for rapid insulin detection was fabricated. Aminated porous silica microparticles (PSiMPs) were synthesized via a facile mini-emulsion method to provide large surface area for covalent immobilization of insulin-binding DNA aptamer (IGA3) by glutaraldehyde cross-linking protocol. A Nickel-salphen type complex with piperidine side chain [Ni(II)-SP] was synthesized with a simple one-pot reaction, and functionalized as an optical label due to strong π-π interaction between aromatic carbons of G-quadruplex DNA aptamer and planar aromatic groups of Ni(II)-SP to form the immobilized IGA3-Ni(II)-SP complex, i.e. the dye-labeled aptamer, thereby bringing yellow colouration to the immobilized G-quartet plane. Optical characterization of aptasensor towards insulin binding was carried out with a fiber optic reflectance spectrophotometer. The maximum reflectance intensity of the immobilized IGA3-Ni(II)-SP complex at 656 nm decreased upon binding with insulin as aptasensor changed to brownish orange colouration in the background. This allows optical detection of insulin as the colour change of aptasensor is dependent on the insulin concentration. The linear detection range of the aptasensor is obtained from 10 to 50 μIU mL-1 (R2 = 0.9757), which conformed to the normal fasting insulin levels in human with a limit of detection (LOD) at 3.71 μIU mL-1. The aptasensor showed fast response time of 40 min and long shelf life stability of >3 weeks. Insulin detection using healthy human serums with informed consent provided by participants suggests the DNA aptamer biosensor was in good agreement with ELISA standard method using BIOMATIK Human INS (Insulin) ELISA Kit.
    Matched MeSH terms: Biosensing Techniques/instrumentation*
  19. Recent uses of carbon nanotubes & gold nanoparticles in electrochemistry with application in biosensing: A review
    Alim S, Vejayan J, Yusoff MM, Kafi AKM
    Biosens Bioelectron, 2018 Dec 15;121:125-136.
    PMID: 30205246 DOI: 10.1016/j.bios.2018.08.051
    The innovation of nanoparticles assumes a critical part of encouraging and giving open doors and conceivable outcomes to the headway of new era devices utilized as a part of biosensing. The focused on the quick and legitimate detecting of specific biomolecules using functionalized gold nanoparticles (Au NPs), and carbon nanotubes (CNTs) has turned into a noteworthy research enthusiasm for the most recent decade. Sensors created with gold nanoparticles or carbon nanotubes or in some cases by utilizing both are relied upon to change the very establishments of detecting and distinguishing various analytes. In this review, we will examine the current utilization of functionalized AuNPs and CNTs with other synthetic mixes for the creation of biosensor prompting to the location of particular analytes with low discovery cutoff and quick reaction.
    Matched MeSH terms: Biosensing Techniques/instrumentation; Biosensing Techniques/methods*; Biosensing Techniques/trends*
  20. Fulltext Recent progress in optical chemical sensors
    Qazi HH, bin Mohammad AB, Akram M
    Sensors (Basel), 2012 Nov 29;12(12):16522-56.
    PMID: 23443392 DOI: 10.3390/s121216522
    Optical chemical sensors have promoted escalating interest in the determination of various pollutants in the environment, which are creating toxicity and may cause serious health problems. This review paper focuses particularly on the recent progress and developments in this field; the working principles and basic classes of optical chemical sensors have been briefly described.
    Matched MeSH terms: Biosensing Techniques*
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