Human papilloma virus DNA-biomarker analysis for cervical cancer: Signal enhancement by gold nanoparticle-coupled tetravalent streptavidin-biotin strategy

Zeolite-iron oxide integrated interdigitated electrode sensor for diagnosing cervical cancer

Cervical cancer is caused by changes in the cervix that lead to precancerous cells and eventually progress to cancer. Human papillomavirus (HPV) infections are the primary cause of cervical cancer. Early detection of HPV is crucial in preventing cervical cancer, and regular screening for HPV infection can identify cell changes before they develop into cancer. While Pap smear tests are reliable for cervical cancer screening, they are critical, expensive, and labor-intensive. Therefore, researchers are focusing on identifying blood-based biomarkers using biosensors for cervical cancer screening. HPV strains 16, 45, and 18 are common culprits in cervical cancer. This study aimed to develop an HPV-16 DNA biosensor on a zeolite-iron oxide (zeolite-IO) modified interdigitated electrode (IDE) sensor. The DNA probe was immobilized on the IDE through amine-modified zeolite-IO, enhancing the hybridization of the target and DNA probe. The detection limit of the DNA-DNA duplex was found to be 7.5 pM with an R2 value of 0.9868. Additionally, control experiments with single and triple mismatched sequences showed no increase in current responses, and the identification of target DNA in a serum-spiked sample indicated specific and selective target identification.

Micro-interdigitated electrodes genosensor based on Au-deposited nanoparticles for early detection of cervical cancer

Genosensor-based electrodes mediated with nanoparticles (NPs) have tremendously developed in medical diagnosis. Herein, we report a facile, rapid, low cost and highly sensitive biosensing strategy for early detection of HPV 18 using gold-nanoparticles (AuNPs) deposited on micro-IDEs. This study represents surface charge transduction of micro-interdigitated electrodes (micro-IDE) alumina insulated with silica, independent and mini genosensor modified with colloidal gold NPs (AuNPs), and determination of gene hybridization for early detection of cervical cancer. The surface of AuNPs deposited micro-IDE functionalized with optimized 3-aminopropyl-triethoxysilane (APTES) followed by hybridization with deoxyribonucleic acid (DNA) virus to develop DNA genosensor. The results of ssDNA hybridization with the ssDNA target of human papillomavirus (HPV) 18 have affirmed that micro-IDE functionalized with colloidal AuNPs resulted in the lowest detection at 0.529 aM. Based on coefficient regression, micro-IDE functionalized with AuNPs produces better results in the sensitivity test (R2 = 0.99793) than unfunctionalized micro-IDE.

Reports on the sensitivity enhancement in interferometric based biosensors by biotin-streptavidin system

Antibody biotinylation is a process of attaching biotin molecules to antibodies by chemically modifying specific functional groups on the antibodies without altering their antigen recognition specificity. Biotin, a small vitamin, forms a strong and specific interaction with the protein streptavidin, resulting in a stable biotin-streptavidin (biotin-STV) complex. This biotin-STV interaction is widely exploited in various biotechnological applications, including biosensors. Biosensors are analytical devices that employ biological recognition elements, such as antibodies, enzymes, or nucleic acids, to detect and quantify target analytes in a sample. Antibodies are commonly used as recognition elements in biosensors due to their high specificity and affinity. In this study, the antibody anti-Bovine Serum Albumin (αBSA) has been biotinylated at different antibody:biotin ratios, and the stability of this labeling over time has been investigated. Furthermore, the sensitivity of the biosensor for detecting the Bovine Serum Albumin (BSA) protein has been compared using the biotinylated antibody and the non-biotinylated form, showing a four-fold improvement in detection. This system was also compared with the Enzyme-Linked ImmunoSorbent Assay (ELISA) technique. The advantages of using biotinylated antibodies in biosensors include increased stability and reproducibility of the biorecognition layer, as well as flexibility in sensor design, as different biotinylated antibodies can be utilized for diverse target analytes without altering the sensor's architecture.

Streptavidin Fe2O3-gold nanoparticles functionalized theranostic liposome for antibiotic resistant bacteria and biotin sensing

Novel methods of sensing and treatment required to elicit potent humoral and cellular immune responses. Here, Streptavidin functionalized α-Fe2O3-Au nanoparticles (STV-Mag) loaded cationic carbomate cholesterol is used as a carrier to release antibacterial thymol drug for Staphylococcus aureus (S. aureus) infected Caenorhabditis elegans (C. elegans). Pertaining to theranostic applications, efficient antimicrobial activity, and non-stimulated drug release and biotin dependent S. aureus growth were studied in-vivo. While STV-Mag was tethered on mercaptobenzoic acid (MBA) molecular cushion for label free streptavidin-biotin electrochemical sensing, the STV-Mag-carbomate cholesterol (STV-Mag-cCHOL liposome) vesicle with loaded drug was tethered on MBA for non-stimulant drug release through specific cholesterol-S. aureus interaction and confirmed electrochemically. Selectivity was confirmed using other pathogens, E. coli, Proteus and Enterococcus bacterium through antimicrobial studies along with S. aureus. The biotin sensing showed linear range from 10-15 to 10-3 M, which was not obtained by conventional methods. Fourier-Transform Infra-red (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Transmission Electron Microscopy (TEM) techniques were used to characterize the nanoparticulate system.

Gold nanourchin enhances detection of Alzheimer's disease biomarker "miRNA-137" on dual electrode sensing surface

Diagnosis of Alzheimer's disease (AD) is a complex task, and at present, neuroimaging such as magnetic resonance imaging and positron emission tomography is commonly used for the diagnosis of AD. This research work developed a new biosensing method with gold nanomaterial to identify AD biomarker of miRNA-137. Gold nanourchin (GNU) was attached on the interdigitated electrode through the silane linker and COOH-ended capture oligonucleotide was immobilized on the GNU surface. This surface helps to quantify the target sequence of miRNA-137 and the detection limit reached to 0.01 pM on the linear range of 0.01-100 pM. With 3δ calculation on the linearity, the determination coefficient was noticed as y = 1.2867x - 2.2697; R²  = 0.9059. The control performances did not show a significant response, indicating the specific identification of target.

Aptamer-based biosensors for virus protein detection

Virus threatens life health seriously. The accurate early diagnosis of the virus is vital for clinical control and treatment of virus infection. Aptamers are small single-stranded oligonucleotides (DNAs or RNAs). In this review, we summarized aptasensors for virus detection in recent years according to the classification of the viral target protein, and illustrated common detection mechanisms in the aptasensors (colorimetry, fluorescence assay, surface plasmon resonance (SPR), surface-enhanced raman spectroscopy (SERS), electrochemical detection, and field-effect transistor (FET)). Furthermore, aptamers against different target proteins of viruses were summarized. The relationships between the different biomarkers of the viruses and the detection methods, and their performances were revealed. In addition, the challenges and future directions of aptasensors were discussed. This review will provide valuable references for constructing on-site aptasensors for detecting viruses, especially the SARS-CoV-2.

Cardiovascular biomarker troponin I biosensor: Aptamer-gold-antibody hybrid on a metal oxide surface

Myocardial infarction (MI) is highly related to cardiac arrest leading to death and organ damage. Radiological techniques and electrocardiography have been used as preliminary tests to diagnose MI; however, these techniques are not sensitive enough for early-stage detection. A blood biomarker-based diagnosis is an immediate solution, and due to the high correlation of troponin with MI, it has been considered to be a gold-standard biomarker. In the present research, the cardiac biomarker troponin I (cTnI) was detected on an interdigitated electrode sensor with various surface interfaces. To detect cTnI, a capture aptamer-conjugated gold nanoparticle probe and detection antibody probe were utilized and compared through an alternating sandwich pattern. The surface metal oxide morphology of the developed sensor was proven by microscopic assessments. The limit of detection with the aptamer-gold-cTnI-antibody sandwich pattern was 100 aM, while it was 1 fM with antibody-gold-cTnI-aptamer, representing 10-fold differences. Further, the high performance of the sensor was confirmed by selective cTnI determination in serum, exhibiting superior nonfouling. These methods of determination provide options for generating novel assays for diagnosing MI.

Nanomaterials for virus sensing and tracking

The effect of the on-going COVID-19 pandemic on global healthcare systems has underlined the importance of timely and cost-effective point-of-care diagnosis of viruses. The need for ultrasensitive easy-to-use platforms has culminated in an increased interest for rapid response equipment-free alternatives to conventional diagnostic methods such as polymerase chain reaction, western-blot assay, etc. Furthermore, the poor stability and the bleaching behavior of several contemporary fluorescent reporters is a major obstacle in understanding the mechanism of viral infection thus retarding drug screening and development. Owing to their extraordinary surface-to-volume ratio as well as their quantum confinement and charge transfer properties, nanomaterials are desirable additives to sensing and imaging systems to amplify their signal response as well as temporal resolution. Their large surface area promotes biomolecular integration as well as efficacious signal transduction. Due to their hole mobility, photostability, resistance to photobleaching, and intense brightness, nanomaterials have a considerable edge over organic dyes for single virus tracking. This paper reviews the state-of-the-art of combining carbon-allotrope, inorganic and organic-based nanomaterials with virus sensing and tracking methods, starting with the impact of human pathogenic viruses on the society. We address how different nanomaterials can be used in various virus sensing platforms (e.g. lab-on-a-chip, paper, and smartphone-based point-of-care systems) as well as in virus tracking applications. We discuss the enormous potential for the use of nanomaterials as simple, versatile, and affordable tools for detecting and tracing viruses infectious to humans, animals, plants as well as bacteria. We present latest examples in this direction by emphasizing major advantages and limitations.

Recent Advances in Signal Amplification to Improve Electrochemical Biosensing for Infectious Diseases

The field of infectious disease diagnostics is burdened by inequality in access to healthcare resources. In particular, “point-of-care” (POC) diagnostics that can be utilized in non-laboratory, sub-optimal environments are appealing for disease control with limited resources. Electrochemical biosensors, which combine biorecognition elements with electrochemical readout to enable sensitive and specific sensing using inexpensive, simple equipment, are a major area of research for the development of POC diagnostics. To improve the limit of detection (LOD) and selectivity, signal amplification strategies have been applied towards these sensors. In this perspective, we review recent advances in electrochemical biosensor signal amplification strategies for infectious disease diagnostics, specifically biosensors for nucleic acids and pathogenic microbes. We classify these strategies into target-based amplification and signal-based amplification. Target-based amplification strategies improve the LOD by increasing the number of detectable analytes, while signal-based amplification strategies increase the detectable signal by modifying the transducer system and keep the number of targets static. Finally, we argue that signal amplification strategies should be designed with application location and disease target in mind, and that the resources required to produce and operate the sensor should reflect its proposed application, especially when the platform is designed to be utilized in low-resource settings. We anticipate that, based on current technologies to diagnose infectious diseases, incorporating signal-based amplification strategies will enable electrochemical POC devices to be deployed for illnesses in a wide variety of settings.

Real-Time Fluorescence Imaging of His-Tag-Driven Conjugation of mCherry Proteins to Silver Nanowires

In this work, we aimed to apply fluorescence microscopy to image protein conjugation to Ni-NTA modified silver nanowires in real time via the His-tag attachment. First, a set of experiments was designed and performed for the mixtures of proteins and silver nanowires in order to demonstrate plasmon enhancement of mCherry protein fluorescence as well as the ability to image fluorescence of single molecules. The results indicated strong enhancement of single-protein fluorescence emission upon coupling with silver nanowires. This conclusion was supported by a decrease in the fluorescence decay time of mCherry proteins. Real-time imaging was carried out for a structure created by dropping protein solution onto a glass substrate with functionalized silver nanowires. We observed specific attachment of mCherry proteins to the nanowires, with the recognition time being much longer than in the case of streptavidin–biotin conjugation. This result indicated that it is possible to design a universal and efficient real-time sensing platform with plasmonically active functionalized silver nanowires.

Nitrogen-Doped Carbon Dots for Selective and Rapid Gene Detection of Human Papillomavirus Causing Cervical Cancer

According to WHO, cervical cancer is considered as one of the most frequently diagnosed cancers and the fourth main source of cancer death in women in 2020 worldwide. Hence, there is a need for development of cervical cancer screening with new rapid and cost-effective methods. Although there are few methods available for HPV identification, these techniques are less sensitive, time-consuming, and costly. An ultra-sensitive, selective, and label-free DNA-based impedimetric electrochemical genosensor is developed in this study to detect HPV-18 for cervical cancer. Electrochemical analysis was performed for the characterization of the sensing platform and for the detection of analyte. A single-stranded 25mer oligonucleotide DNA probe was immobilized onto a nitrogen-doped carbon nanodot-modified ITO electrode. Furthermore, the hybridization event was measured by testing the complementary single stranded DNA sequence in the samples. The sensor could distinguish between complementary as well as non-complementary sequences. Herein, impedance quantification demonstrated a limit of detection of 0.405 fM. The developed genosensor showed high selectivity toward HPV-18 in the clinical samples. This sensing platform can be considered as a rapid and selective method for the screening of HPV-18.

A DNA Electrochemical Sensor via Terminal Protection of Small-Molecule-Linked DNA for Highly Sensitive Protein Detection

The qualitative and quantitative determination of marker protein is of great significance in the life sciences and in medicine. Here, we developed an electrochemical DNA biosensor for protein detection based on DNA self-assembly and the terminal protecting effects of small-molecule-linked DNA. This strategy is demonstrated using the small molecule biotin and its receptor protein streptavidin (SA). We immobilized DNA with a designed structure and sequence on the surface of the gold electrode, and we named it M1-Biotin DNA. M1-Biotin DNA selectively combines with SA to generate M1-Biotin-SA DNA and protects M1-Biotin DNA from digestion by EXO III; therefore, M1-Biotin DNA remains intact on the electrode surface. M1-Biotin-SA DNA was modified with methylene blue (MB); the MB reporter molecule is located near the surface of the gold electrode, which generates a substantial electrochemical signal during the detection of SA. Through this strategy, we can exploit the presence or absence of an electrochemical signal to provide qualitative target protein determination as well as the strength of the electrochemical signal to quantitatively analyze the target protein concentration. This strategy has been proven to be used for the quantitative analysis of the interaction between biotin and streptavidin (SA). Under optimal conditions, the detection limit of the proposed biosensor is as low as 18.8 pM, and the linear range is from 0.5 nM to 5 μM, showing high sensitivity. The detection ability of this DNA biosensor in complex serum samples has also been studied. At the same time, we detected the folate receptor (FR) to confirm that this strategy can be used to detect other proteins. Therefore, this electrochemical DNA biosensor provides a sensitive, low-cost, and fast target protein detection platform, which may provide a reliable and powerful tool for early disease diagnosis.

Biomolecular assembly on interdigitated electrode nanosensor for selective detection of insulin-like growth factor-1

This research is focussed to quantify IGF1 by electroanalytical analysis on InterDigitated electrode surface and characterized by the microscopic observations. For the detection, antibody and aptamer were used to analyze the level of IGF1. The sandwich pattern (aptamer-IGF1-antibody) was designed on the chemically modified IDE surface and reached the limit of detection to 10 fM with 100 folds enhancement in the sensitivity. Different control experiments (absence of IGF1, binding with IGF2 and with non-complementary aptamer) were failed to show the current changes, discriminated the specific detection. A good detection strategy is to complement the currently following imaging systems for AAA.

High yield gold nanoparticle-based DNA isolation method for human papillomaviruses genotypes from cervical cancer tissue samples

Gold nanoparticles (AuNPs) are commonly used in biosensors of various kinds. However, its application to extract DNA from cancer tissues has not been extensively studied. The purification of DNA from cancer tissues is an important step in diagnostic and therapeutic development. Almost, all cervical cancer cases are associated with high-risk human papillomavirus (HR-HPV) infection. Accurate viral diagnosis has so far relied on the extraction of adequate amounts of DNA from formalin-fixed, paraffin-embedded (FFPE) tissue samples. Till now, no specific and sensitive DNA purification method has been introduced for the extraction of HR-HPV from FFPE tissue. Since the commercially available purification kits are not sensitive and specific enough for HR-HPV DNA targets, in this study, a DNA purification method was designed based on AuNPs to purify sufficient amounts of HR-HPV DNA from cervical cancer tissue samples. AuNPs were coated with a series of oligonucleotide probes to hybridize to specific DNA sequences of HR-HPV genotypes. Results showed that 733 out of 800 copies of type-specific HPV DNA were recovered with complete specificity, compared to 36 copies with a standard commercial kit (Qiagen FFPE). The high yield of DNA (91.6%) is the main advantage of the AuNPs-probe purification method.

Biosensors and biomarkers for determining gestational diabetes mellitus and jaundice in children

Gestational diabetes and jaundice are the correlated diseases predominantly found in mother and newborn child. Jaundice is a neonatal complication with an increased risk when mother has gestational diabetes. Mothers with diabetes at an early stage of gestational age are at higher risk for hyperbilirubinemia (jaundice) and hypoglycemia. So, it is mandatory to monitor the condition of diabetes and jaundice during the pregnancy period for a healthy child and safest delivery. On the other hand, nanotechnology has displayed a rapid advancement that can be implemented to overcome these issues. The development of high-performance diagnosis using appropriate biomarkers provides their efficacy in the detection gestational diabetes and jaundice. This review covers the aspects from a fast-developing field to generate nanosensors in the nanosized dimensions for the applications to overcome these complications by coupling diagnostics with biomarkers. Further, the serum-based biomarkers have been discussed for these inborn complications and also the diagnosis with the current trend.

Split-type electrochemiluminescent gene assay platform based on gold nanocluster probe for human papillomavirus diagnosis

Persistent high-risk human papillomavirus (HPV) infection is the leading cause of cervical cancer. Efficient detection of HPV16 E7 is necessary for early diagnosis and cure of the disease. Here, a novel and high-performance Au nanocluster (AuNC) probe-based split-type electrochemiluminescent (ECL) assay platform has been established to detect these oncogenes, in which the nucleic acid hybridization assay and the ECL measurements are performed independently. The proposed approach combines superior magnetic nanobead enrichment and separation technology, specific nucleic acid hybridization technology, and high-efficiency AuNC probe ECL strategy, and shows excellent advantages. First, the split-type ECL sensing platform can effectively avoid interference from biological samples and adequately uses the ECL efficiency of the AuNC probe. Furthermore, the ultrahigh sensitivity assay of HPV DNA can be achieved without any complex nucleic acid amplification technique. Taking advantage of the above merits of split-type detection, the ECL DNA sensor achieved ideal low detection of 6.8 aM and a wide dynamic range bridging 10 orders of magnitude HPV16 E7. Furthermore, together with its favorable and powerful specificity, high sensitivity, and good selectivity, this strategy could detect HPV16 E7 DNA in human samples, which showed great consistency with the FDA-approved approach (Hybrid capture 2, HC2). Therefore, this work proposes a facile and reliable split-type ECL platform for HPV diagnosis and shows great potential for the early diagnosis of other diseases.

Nano-silica embedded polydimethylsiloxane on interdigitated sensor as adhesive polymer for detecting lung cancer mutation

Non-small cell lung cancer (NSCLC) incited by epidermal growth factor receptor (EGFR) mutation makes up ∼85% of lung cancer diagnosed and death cases worldwide. The presented study introduced an alternative approach in detecting EGFR mutation using nano-silica integrated with polydimethylsiloxane (PDMS) polymer on interdigitated electrode (IDE) sensor. A 400 μm gap-sized aluminum IDE was modified with nano-polymer layer, which was made up of silica nanoparticles and PDMS polymer. IDE and PDMS-coated IDE (PDMS/IDE) were imaged using electron microscopes that reveals its smooth and ideal sensor morphology. The nano-silica-integrated PDMS/IDE surface was immobilized with EGFR probe and target to specify the lung cancer detection. The sensor specificity was justified through the insignificant current readouts with one-base mismatch and noncomplementary targets. The sensitivity of nano-silica-integrated PDMS/IDE was examined with mutant target spiked in human serum, where the resulting current affirms the detection of EGFR mutation. Based on the slope of the calibration curve, the sensitivity of nano-silica-integrated PDMS/IDE was 2.24E-9 A M^-1 . The sensor recognizes EGFR mutation lowest at 1 aM complementary mutant target; however, the detection limit obtained based on 3σ calculation is 10 aM with regression value of 0.97.

Metal Nanoparticles for Electrochemical Sensing: Progress and Challenges in the Clinical Transition of Point-of-Care Testing

With the rise in public health awareness, research on point-of-care testing (POCT) has significantly advanced. Electrochemical biosensors (ECBs) are one of the most promising candidates for the future of POCT due to their quick and accurate response, ease of operation, and cost effectiveness. This review focuses on the use of metal nanoparticles (MNPs) for fabricating ECBs that has a potential to be used for POCT. The field has expanded remarkably from its initial enzymatic and immunosensor-based setups. This review provides a concise categorization of the ECBs to allow for a better understanding of the development process. The influence of structural aspects of MNPs in biocompatibility and effective sensor design has been explored. The advances in MNP-based ECBs for the detection of some of the most prominent cancer biomarkers (carcinoembryonic antigen (CEA), cancer antigen 125 (CA125), Herceptin-2 (HER2), etc.) and small biomolecules (glucose, dopamine, hydrogen peroxide, etc.) have been discussed in detail. Additionally, the novel coronavirus (2019-nCoV) ECBs have been briefly discussed. Beyond that, the limitations and challenges that ECBs face in clinical applications are examined and possible pathways for overcoming these limitations are discussed.

Highly sensitive and selective acute myocardial infarction detection using aptamer-tethered MoS2 nanoflower and screen-printed electrodes

Acute myocardial infarction (AMI) is one of the leading causes of death worldwide. Cardiac troponin I (cTn1) is a commonly used biomarker for the diagnosis of AMI. Although there are various detection methods for the rapid detection of cTn1 such as optical, electrochemical, and acoustic techniques, electrochemical aptasensing techniques are commonly used because of their ease of handling, portability, and compactness. In this study, an electrochemical cTn1 biosensor, MoS₂ nanoflowers on screen-printed electrodes assisted by aptamer, was synthesized using hydrothermal technique. Field emission scanning electron microscopy revealed distinct 2D nanosheets and jagged flower-like 3D MoS₂ nanoflower structure, with X-ray diffraction analysis revealing well-stacked MoS₂  layers. Voltammetry aptasensing of cTn1 ranges from 10 fM to 1 nM, with a detection limit at 10 fM and a sensitivity of 0.10 nA µM^-1  cm^-2 . This is a ∼fivefold improvement in selectivity compared with the other proteins and human serum. This novel aptasensor retained 90% of its biosensing activity after 6 weeks with a 4.3% RSD and is a promising high-performance biosensor for detecting cTn1.

Detection of interleukin-8 on microgapped dual electrodes for measuring asthma complication

Detection of asthma by a suitable biomarker is mandatory for the early identification, which helps in providing a right medication for the complete cure. Interleukins (ILs) have played a major role in asthma; in particular IL-8 is highly correlated with severe asthma. This research was focused on to detect IL-8 level by its partner antibody on a microgapped dual electrodes sensor. The sensing surface was modified into graphene oxide (GO), and an antibody was fixed by using the amine-aldehyde linker. GO enhanced the antibody immobilization and the consequence electric current flow upon interacting with IL-8. The detection limit of IL-8 was reached to 10 pg/mL in a linear range from 1 to 10,000 pg/mL with the regression of y = 0.7246x - 0.906 (R² = 0.9758); further, the sensitivity falls at 1 pg/mL. The surface does not show the antifouling effect with control antibody, and proteins, indicating the specific IL-8 detection. The detection of IL-8 helps in diagnosing and solving the related problems of asthmatic patients.

Electroanalysis on an Interdigitated Electrode for High-Affinity Cardiac Troponin I Biomarker Detection by Aptamer-Gold Conjugates

The primary reasons for myocardial infarction (MI) are pericarditis, arrhythmia, and heart failure, causing predominant deaths worldwide. Patients need a potential diagnostic system and treatment before cardiomyocyte damage. Cardiac biomarkers are released from myocytes immediately after a heart attack. Troponin is an efficient biomarker released from dead cells within a few hours. Aptamers are artificial antibodies used effectively in the biosensor field for biomarker detection. Along with aptamers, the application of nanomaterials is also expected to enhance the detection limits of biosensors. In this investigation, selected aptamers against cardiac troponin I (cTnI) were conjugated with gold nanoparticles (GNPs) to diagnose MI and compared with an aptamer-only control group on an interdigitated electrode surface. Based on electroanalysis, cTnI was detected at concentrations as low as 1 fM, and the detection limit improved to 100 aM when the aptamer was conjugated with GNP. In addition, aptamer-GNP conjugates increased the current level at the tested concentrations of cTnI. Control experiments with noncomplementary aptamers and relevant proteins did not result in notable changes in the current, demonstrating the selective detection of cTnI.

Anxiety determination by antibody-conjugated nanoparticles on an interdigitated electrode sensor

This work focused on the detection of cortisol on an interdigitated electrode sensor surface using an anti-cortisol antibody. To improve immobilization, antibodies were conjugated with silver nanoparticles and attached to the surface of the sensor. Cortisol interacted in a dose-dependent manner on the antibody-immobilized sensor surface, and current changes were observed. Linear regression analysis was performed by a 3σ calculation, and the limit of detection fell into the range of 0.01 and 0.1 ng/mL. The sensitivity of cortisol was calculated to be 0.01 ng/mL and the sensor discriminated against other hormones, namely norepinephrine and progesterone, with higher selectivity for cortisol. This result represented the selective detection of cortisol with high performance, which can help to determine anxiety disorders.

DNA-RNA complementation on silicon wafer for thyroid cancer determination

One of the current issues with thyroid tumor is early diagnosis as it makes the higher possibility of curing. This research was focused to detect and quantify the level of specific target sequence complementation of miR-222 with capture DNA sequence on interdigitated electrode (IDE) sensor. The aluminum electrode with the gap and finger sizes of 10 µm was fabricated on silicon wafer, further the surface was amine-functionalized for accommodating carboxylated-DNA probe. With DNA-target RNA complementation, the detection limit was attained to be 1 fM as estimated by a linear regression analysis [y = 1.5325x - 2.1171 R² = 0.9065] and the sensitivity was at the similar level. Current responses were higher by increasing the target RNA sequence concentrations. Control experiments with mismatched/noncomplementary sequences were failed to complement the capture DNA sequence immobilized on IDE, indicating the specific target validation. This research helps diagnosing and identifying the progression with thyroid tumor and miRNA being a potential "marker" in atypia diagnosis.

MicroRNA-155 complementation on a chemically functionalized dual electrode surface for determining breast cancer

This study correlated and quantified the expression of microRNA-155 with breast cancer to determine breast cancer progression. The target microRNA-155 sequence was identified by complementation on a capture-probe sequence-immobilized interdigitated dual electrode surface. The sensitivity was found to be 1 fM, and the limit of detection fell between 1 and 10 fM. The specific sequence selectivity with single mismatches, triple mismatches, and noncomplementary bases failed to complement the capture-probe sequence. The obtained results demonstrate the selective determination of the microRNA-155 sequence and can help to diagnose breast cancer.

Detection of microRNA-335-5p on an Interdigitated Electrode Surface for Determination of the Severity of Abdominal Aortic Aneurysms

Abdominal aortic aneurysm (AAA) refers to the enlargement of the lower artery of the abdominal aorta, and identification of an early detection tool is urgently needed for diagnosis. In the current study, an interdigitated electrode (IDE) sensing surface was used to identify miRNA-335-5p, which reflects the formation of AAAs. The uniformity of the silica material was observed by 3D profilometry, and the chemically modified highly conductive surface improved the detection via the I-V mode. The targeted miRNA-335-5p was detected in a dose-dependent manner and based on linear regression and 3σ analyses, the sensitivity was determined to be 1 fM with a biotinylated probe. The high specificity was shown by discriminating the target sequence from noncomplementary and single- and triple-mismatched sequences. These outputs demonstrated the high-performance detection of miRNA-335-5p with good reproducibility for determination of the severity of AAA.

Targeted DNA complementation on a 1,1'-carbonyldiimidazole-functionalized surface for identifying Mycobacterium tuberculosis

Herein, a rapid and sensitive current-volt measurement was developed for identifying the IS6110 DNA sequence to diagnose Mycobacterium tuberculosis (TB). An aminated capture probe was immobilized on a 1,1'-carbonyldiimidazole-functionalized interdigitated electrode (IDE) silica substrate, and the target sequence was detected by complementation. It was found that all tested concentrations displayed a higher response in current changes than the control, and the limit of detection was 10 fM. The sensitivity ranged from 1 to 10 fM. The control sequences with single-, triple-mismatch and noncomplementary sequences showed great discrimination. This rapid and easy DNA detection method helps to identify M. tuberculosis for early-stage diagnosis of TB.

Coordination of Nanoconjugation with an Antigen/Antibody for Efficient Detection of Gynecological Tumors

Cervical, ovarian, and endometrial cancers are common in the female reproductive system. Cervical cancer starts from the cervix, while ovarian cancer develops when abnormal cells grow in the ovary. Endometrial or uterine cancer starts from the lining of the womb in the endometrium. Approximately 12,000 women are affected every year by cervical cancer in the United States. Squamous cell carcinoma antigen (SCC-Ag) is a well-established biomarker in serum for diagnosing gynecological cancers, and its levels were observed to be elevated in cervical, ovarian, and endometrial cancer patients. Moreover, SCC-Ag was used to identify the tumor size and progression stages. Various biosensing systems have been proposed to identify SCC-Ag; herein, enhanced interdigitated electrode sensing is presented with the use of gold nanoparticles (GNPs) to conjugate an antigen/antibody. It was proved that the limit of detection is 62.5 fM in the case of antibody-GNP, which is 2-fold higher than that by SCC-Ag-GNP. Furthermore, the antibody-GNP-modified surface displays greater current increases with concomitant dose-dependent SCC-Ag levels. High analytical performance was shown by the discrimination against α-fetoprotein and CYFRA 21-1 at 1 pM. An enhanced sensing system is established for gynecological tumors, representing an advance from the earlier detection methods.

Glucose oxidase complexed gold-graphene nanocomposite on a dielectric surface for glucose detection: a strategy for gestational diabetes mellitus

BACKGROUND

Gestational diabetes mellitus is a commonly occurring metabolic disorder during pregnancy, affecting >4% of pregnant women. It is generally defined as the intolerance of glucose with the onset or initial diagnosis during pregnancy. This illness affects the placenta and poses a threat to the baby as it affects the supply of proper oxygen and nutrients.

PURPOSE

Due to the high percentage of affected pregnant women, it should be mandatory to evaluate glucose levels during pregnancy and there is a need for a continuous monitoring system.

METHODS

Herein, the investigators modified the interdigitated (di)electrodes (IDE) sensing surface to detect the glucose on covalently immobilized glucose oxidase (GOx) with the graphene. The characterization of graphene and gold nanoparticle (GNP) was performed by high-resolution microscopy.

RESULTS

Sensitivity was found to be 0.06 mg/mL and to enhance the detection, GOx was complexed with GNP. GNP-GOx was improved the sensitive detection twofold from 0.06 to 0.03 mg/mL, and it also displayed higher levels of current changes at all the concentrations of glucose that were tested. High-performance of the above IDE sensing system was attested by the specificity, reproducibility and higher sensitivity detections. Further, the linear regression analysis indicated the limit of detection to be between 0.02 and 0.03 mg/mL.

CONCLUSION

This study demonstrated the potential strategy with nanocomposite for diagnosing gestational diabetes mellitus.

Complementation of ELISA and an Interdigitated Electrode Surface in Gold Nanoparticle Functionalization for Effective Detection of Human Blood Clotting Defects

Developing an enhanced diagnosis using biosensors is important for the treatment of patients before disease complications arise. Improving biosensors would enable the detection of various low-abundance disease biomarkers. Efficient immobilization of probes/receptors on the sensing surface is one of the efficient ways to enhance detection. Herein, we introduced the pre-alkaline sensing surface with amine functionalization for capturing gold nanoparticle (GNP) conjugated to human blood clotting factor IX (FIX), and we demonstrated the excellent performance of the strategy. We have chosen the enzyme-linked immunosorbent assay (ELISA) and the interdigitated electrode (IDE), which are widely used, to demonstrate our method. The optimal amount for silanization has been found to be 2.5%, and 15-nm-sized GNPs are ideal and characterized. The limit of FIX detection was attained with ELISA at 100 pM with the premixed GNPs and FIX, which shows 60-fold improvement in sensitivity without biofouling, as compared to the conventional ELISA. Further, FIX was detected with higher specificity in human serum at a 1:1280 dilution, which is equivalent to 120 pM FIX. These results were complemented by the analysis on IDE, where improved detection at 25 pM was achieved, and FIX was detected in human serum at the dilution of 1:640. These optimized surfaces are useful for improving the detection of different diseases on varied sensing surfaces.