Antibody-functionalized magnetic nanoparticles for the detection of carcinoembryonic antigen using a flow-injection electrochemical device

Biocompatible graphene-zirconia nanocomposite as a cyto-safe immunosensor for the rapid detection of carcinoembryonic antigen

Graphene-based materials have gained remarkable attention in numerous disciplines owing to their unique electrochemical properties. Out of various hybridized nanocomposites, graphene-zirconia nanocomposite (GZ) was distinctive due to its biocompatibility. Zirconia nanoparticles serve as spacers that reduce the stacking of graphene and improve the electrochemical performance of the material. Considering that lungs and skin suffer the greatest exposure to nanoparticles, this study aimed to evaluate the cytotoxicity of the as-synthesized GZ nanocomposites on MRC5 (lung cells) and HaCaT (skin cells) via morphological observation and cell viability assay using 3-(4,5 dimethylthiazol-2-yl)-(2,5-diphenyltetrazolium bromide) tetrazolium (MTT). GZ-treated cells showed a comparable proliferation rate and morphology with untreated cells under microscopic evaluation. Based on MTT results, the IC₅₀ values of GZ were > 500 µg/ml for MRC5 and HaCaT cells. The excellent biocompatibility was the supremacy of GZ over other nanocomposites applied as electrode materials in biosensors. GZ was functionalized with biolinker for the detection of carcinoembryonic antigen (CEA). The proposed immunosensor exhibited good responses towards CEA detection, with a 4.25 pg/ml LOD and correlation coefficient of R² = 0.99 within a linear working range from 0.01 to 10 ng/ml. The performance of the immunosensor to detect CEA present in human serum was also evaluated. Good recovery of CEA was found, suggesting that the proposed immunosensor possess a high affinity to CEA even in a complex biological matrix, rendering it a promising sensing platform for real sample analysis and open a new way for the detection of cancer-associated proteins.

Biosensing and Delivery of Nucleic Acids Involving Selected Well-Known and Rising Star Functional Nanomaterials

In the last fifteen years, the nucleic acid biosensors and delivery area has seen a breakthrough due to the interrelation between the recognition of nucleic acid's high specificity, the great sensitivity of electrochemical and optical transduction and the unprecedented opportunities imparted by nanotechnology. Advances in this area have demonstrated that the assembly of nanoscaled materials allows the performance enhancement, particularly in terms of sensitivity and response time, of functional nucleic acids' biosensing and delivery to a level suitable for the construction of point-of-care diagnostic tools. Consequently, this has propelled detection methods using nanomaterials to the vanguard of the biosensing and delivery research fields. This review overviews the striking advancement in functional nanomaterials' assisted biosensing and delivery of nucleic acids. We highlight the advantages demonstrated by selected well-known and rising star functional nanomaterials (metallic, magnetic and Janus nanomaterials) focusing on the literature produced in the past five years.

Aptamer-Based Microchip Electrophoresis Assays for Amplification Detection of Carcinoembryonic Antigen

Microchip electrophoresis (MCE), regarded as a miniaturized version of capillary electrophoresis (CE), has exhibited prominent advantages in terms of low sample consumption, rapid analysis times, easy operation, efficient resolution of compounds, and increased throughput. This technology has led to more research focus on analysis particularly in hospital settings for clinical diagnostics. However, since the channels in microchip are very small, achieving the desired assay sensitivity on a microfluidic platform remains a challenge. Here, we describe aptamer-based MCE assays for amplification detection of carcinoembryonic antigen (CEA) in human serum.

Superparamagnetic nanoarchitectures for disease-specific biomarker detection

Synthesis, bio-functionalization, and multifunctional activities of superparamagnetic-nanostructures have been extensively reviewed with a particular emphasis on their uses in a range of disease-specific biomarker detection and associated challenges.

Novel epoxy-silica nanoparticles to develop non-enzymatic colorimetric probe for analytical immuno/bioassays

We have developed a novel method to develop epoxy silica nanoparticles (EfSiNP) in a single pot. High surface coverage of epoxy functional groups between 150 and 57000 molecules per particles (∼10¹³-10¹⁶ molecules/mL of 200 nm EfSiNPs) was achieved for different preparation conditions. We then created a red colored probe by conjugating Fuchsin dye to the epoxy functionalities of EfSINPs. Anti-mouse IgG was co-immobilized with Fuchsin and their ratios were optimized for achieving optimum ratios by testing those in functional assays. Dye to antibody ratios were in good negative correlation with a coefficient of -1.00 measured at a confidence level of over 99%. We employed the developed non-enzymatic colorimetric immunonanoprobe for detecting mouse IgG in a direct immunoassay format. We achieved a sensitivity of 427 pg/mL with the assay.

Recent Advances Incorporating Superparamagnetic Nanoparticles into Immunoassays

Superparamagnetic nanoparticles (SPMNPs) have attracted interest for various biomedical applications due to their unique magnetic behavior, excellent biocompatibility, easy surface modification, and low cost. Their unique magnetic properties, superparamagnetism, and magnetophoretic mobility have led to their inclusion in immunoassays to enhance biosensor sensitivity and allow for rapid detection of various analytes. In this review, we describe SPMNP characteristics valuable for incorporation into biosensors, including the use of SPMNPs to increase detection capabilities of surface plasmon resonance and giant magneto-resistive biosensors. The current status of SPMNP-based immunoassays to improve the sensitivity of rapid diagnostic tests is reviewed, and suggested strategies for the successful adoption of SPMNPs for immunoassays are presented.

Generalized Scaling and the Master Variable for Brownian Magnetic Nanoparticle Dynamics

Understanding the dynamics of magnetic particles can help to advance several biomedical nanotechnologies. Previously, scaling relationships have been used in magnetic spectroscopy of nanoparticle Brownian motion (MSB) to measure biologically relevant properties (e.g., temperature, viscosity, bound state) surrounding nanoparticles in vivo. Those scaling relationships can be generalized with the introduction of a master variable found from non-dimensionalizing the dynamical Langevin equation. The variable encapsulates the dynamical variables of the surroundings and additionally includes the particles' size distribution and moment and the applied field's amplitude and frequency. From an applied perspective, the master variable allows tuning to an optimal MSB biosensing sensitivity range by manipulating both frequency and field amplitude. Calculation of magnetization harmonics in an oscillating applied field is also possible with an approximate closed-form solution in terms of the master variable and a single free parameter.

Aptamer-based microchip electrophoresis assays for amplification detection of carcinoembryonic antigen

BACKGROUND

Carcinoembryonic antigen (CEA) as one of the most widely used tumor markers is used in the clinical diagnosis of colorectal, pancreatic, gastric, and cervical carcinomas. We developed an aptamer-based microchip electrophoresis assay technique for assaying CEA in human serum for cancer diagnosis.

METHODS

The magnetic beads (MBs) are employed as carriers of double strand DNA that is formed by an aptamer of the target and a complementary DNA of the aptamer. After the aptamer in the MB-dsDNA conjugate binds with the target, the complementary DNA was released from the MB-dsDNA conjugate. The released complementary DNA hybridizes with a fluorescein amidite (FAM) labeled DNA, and forms a DNA duplex, which triggers the selective cleavage of FAM labeled DNA by nicking endonuclease Nb.BbvCI, and generating a FAM labeled DNA segment. The released complementary DNA hybridizes with another FAM labeled DNA, resulting in a continuous cleavage of FAM labeled DNA, and the generation of large numbers of FAM labeled DNA segments. In MCE laser induced fluorescence detection (LIF), the FAM labeled DNA segment is separated and detected.

RESULTS

The linear range for CEA was 130 pg/ml-8.0 ng/ml with a correlation coefficient of 0.9916 and a detection limit of 68 pg/ml. The CEA concentration in the serum samples from healthy subjects was found to be in the range 1.3 ng/ml to 3.2 ng/ml. The CEA concentration in the samples from cancer patients was found to be >15 ng/ml.

CONCLUSIONS

This method may become a useful tool for rapid analysis of CEA and other tumor markers in biomedical analysis and clinical diagnosis.

Ultrasensitive colorimetric carcinoembryonic antigen biosensor based on hyperbranched rolling circle amplification

In this study, a hyperbranched rolling circle amplification (HRCA)-based colorimetric biosensor for carcinoembryonic antigen (CEA) is developed with high sensitivity and specificity. A CEA aptamer can bind with its target (CEA) to form a complex due to their high affinity, and the introduced CDNA cannot hybridize with the aptamer. Thus, free CDNA can propagate the HRCA reaction to form a large number of single-stranded DNA (ss-DNA). ss-DNA can be easily adsorbed onto AuNPs and prevent salt-induced AuNPs aggregation, which causes the change in the color of the system. It is found that the absorbance intensity ratio (A520/A660) has a linear relationship with the concentration of the target in the range of 5 pM-0.5 nM, and the detection limit is as low as 2 pM (S/N = 3).

Electrochemical biotin detection based on magnetic beads and a new magnetic flow cell for screen printed electrode

The use of the first flow-cell for magnetic assays with an integrated magnet is reported here. The flow injection analysis system (FIA) is used for biotin determination. The reaction scheme is based on a one step competitive assay between free biotin and biotin labeled with horseradish peroxidase (B-HRP). The mixture of magnetic beads modified with streptavidin (Strep-MB), biotin and B-HRP is left 15 min under stirring and then a washing step is performed. After that, 100 μL of the mixture is injected and after 30s 100 μL of 3,3',5,5'-Tetramethylbenzidine (TMB) is injected and the FIAgram is recorded applying a potential of -0.2V. The linear range obtained is from 0.01 to 1 nM of biotin and the sensitivity is 758 nA/nM. The modification and cleaning of the electrode are performed in an easy way due to the internal magnet of the flow cell.

A dual amplification strategy for ultrasensitive electrochemiluminescence immunoassay based on a Pt nanoparticles dotted graphene–carbon nanotubes composite and carbon dots functionalized mesoporous Pt/Fe

A facile and sensitive ECL immunosensor has been designed using Pt/Gr–CNTs as a platform and Pt/Fe@CDs as bionanolabels.

Electrochemical immunosensor based on nanoporpus gold loading thionine for carcinoembryonic antigen

Nanoporous gold (NPG) has recently received considerable attention in analytical electrochemistry because of its good conductivity and large specific surface area. A facile layer-by-layer assembly technique fabricated NPG was used to construct an electrochemical immunosensor for carcinoembryonic antigen (CEA). NPG was fabricated on glassy carbon (GC) electrode by alternatively assembling gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs) using 1,4-benzenedimethanethiol as a cross-linker, and then AgNPs were dissolved with HNO3. The thionine was absorbed into the NPG and then gold nanostructure was electrodeposited on the surface through the electrochemical reduction of gold chloride tetrahydrate (HAuCl4). The anti-CEA was directly adsorbed on gold nanostructure fixed on the GC electrode. The linear range of the immunosensor was from 10 pg mL(-1) to 100 ng mL(-1) with a detection limit of 3 pg mL(-1) (S/N=3). The proposed immunosensor has high sensitivity, wide linear range, low detection limit, and good selectivity. The present method could be widely applied to construct other immunosensors.

Electrochemical immunoassay of carcinoembryonic antigen based on TiO2–graphene / thionine / gold nanoparticles composite

A novel multilayer film based on gold nanoparticles (AuNPs), thionine (Thi), and TiO2–graphene (TiO2–Gr) was exploited to develop a highly sensitive amperometric immunosensor for detecting carcinoembryonic antigen (CEA). Firstly, Nafion–TiO2–Gr homogeneous composite was dropped on the surface of a glassy carbon electrode (GCE). Then Thi was chemisorbed by the TiO2–Gr–Nafion composite. Furthermore, the negative ly charged AuNPs were chemisorbed onto Thi film through the electrostatic force with the amino groups of Thi. Cyclic voltammetry (CV) was employed to characterize the assembly process and the performance of the immunosensor. Because of the synergistic effect of the AuNPs, Thi, and the unique properties of TiO2–Gr, the obtained immunosensor exhibited a wide linear response to CEA in two ranges from 0.1 to 10.0 ng mL−1 and from 10.0 to 120.0 ng mL−1 with a relatively low detection limit of 0.01 ng mL−1 (S/N = 3), as well as good stability and repeatability.

The use of magnetic nanoparticles in analytical chemistry

Magnetic nanoparticles uniquely combine superparamagnetic behavior with dimensions that are smaller than or the same size as molecular analytes. The integration of magnetic nanoparticles with analytical methods has opened new avenues for sensing, purification, and quantitative analysis. Applied magnetic fields can be used to control the motion and properties of magnetic nanoparticles; in analytical chemistry, use of magnetic fields provides methods for manipulating and analyzing species at the molecular level. In this review, we describe applications of magnetic nanoparticles to analyte handling, chemical sensors, and imaging techniques.

A novel label-free amperometric immunosensor for carcinoembryonic antigen based on redox membrane

A label-free immunosensor was developed to detect the presence of an antigen. This immunosensor was based on the modulation of the electrochemistry of the surface bound redox species K(3)Fe(CN)(6) (FC). The model antigen was carcinoembryonic antigen (CEA) and the model epitope was the antibody of CEA (anti-CEA). Glassy carbon (GC) electrode surfaces were first drop-coated with a mixture of FC and chitosan and air-dried. The electrode surface was then covered with nafion membrane, which contained gold nanoparticles. After binding with polyethyleneimine (PEI), glutaraldehyde (GA) was used to cross-link PEI and anti-CEA. Binding of CEA to the surface bound epitope resulted in attenuation of the FC electrochemistry. Under optimal conditions, the response of the label-free immunosensor had a linear range of 0.01-150 ng mL(-1) with a detection limit of 3 pg mL(-1) (S/N = 3). Its response was better than those of radioimmunoassays, enzyme-linked immunosorbent assays, and chemiluminescence assays.

Electrochemical immunosensors for antibodies to peanut allergen ara h2 using gold nanoparticle-peptide films

Life-threatening allergies to peanuts and tree nuts can be revealed by detecting antibodies (IgEs) to their allergens in patient serum. Herein, we compare several immunosensor-like methodologies for sensitive detection of antibodies to a peptide sequence from the major peanut allergen, Arachis hypogaea 2 (Ara h2). The sensors feature a synthetic peptide layer of the major IgE-binding epitope from Ara h2 attached to a dense gold nanoparticle (AuNP) film on a pyrolytic graphite (PG) electrode. The AuNP-peptide sensor was used to determine model chicken antipeanut antibodies (IgY) in serum. Faradaic and nonfaradaic impedance strategies were compared to amperometric detection. Measurements employed goat antichicken secondary antibodies (Ab(2)) labeled with horseradish peroxidase (HRP) to bind to IgY on the sensor and provide amplified signals. The best impedimetric sensor configuration featured HPR-catalyzed precipitation of the enzyme product onto the sensor measured by nonfaradaic impedance. This sensor configuration had the best detection limit (DL) of 5 pg mL(-1) and the best linear range of over 5 orders of magnitude (from 5 pg mL(-1) to 1 microg mL(-1)) for IgY antibody in undiluted calf serum. This DL was 100-fold lower than label-free impedimetric immunosensors (0.5 ng mL(-1)) and 60-fold lower than when using HRP-Ab(2) in amperometric immunosensors (0.3 ng mL(-1)).

Half-antibody functionalized lipid-polymer hybrid nanoparticles for targeted drug delivery to carcinoembryonic antigen presenting pancreatic cancer cells

Current chemotherapy regimens against pancreatic cancer are met with little success as poor tumor vascularization significantly limits the delivery of oncological drugs. High-dose targeted drug delivery, through which a drug delivery vehicle releases a large payload upon tumor localization, is thus a promising alternative strategy against this lethal disease. Herein, we synthesize anti-carcinoembryonic antigen (CEA) half-antibody conjugated lipid-polymer hybrid nanoparticles and characterize their ligand conjugation yields, physicochemical properties, and targeting ability against pancreatic cancer cells. Under the same drug loading, the half-antibody targeted nanoparticles show enhanced cancer killing effect compared to the corresponding nontargeted nanoparticles.