Identification of human skeletal muscle from a tissue fragment by detection of human myoglobin using a double-sandwich ELISA

Dual-modality impedimetric immunosensor for early detection of prostate-specific antigen and myoglobin markers based on antibody-molecularly imprinted polymer

A new dual-modality immunosensor based on molecularly imprinted polymer (MIP) and a nanostructured biosensing layer has fabricated for the simultaneous detection of two important markers including prostate-specific antigen (PSA) and myoglobin (Myo) in human serum and urine samples. In the first step, 3,3'-dithiodipropionic acid di(N-hydroxysuccinimide ester) (DSP) was self-assembled on a gold screen printed electrode (SPE). Then, the target proteins were attached covalently to the DSP-SPE. The imprinted cocktail polymer ((MIP(PSA, Myo)-SPE)) was synthesized at the SPE surface using acrylamide as monomer, N,N'-methylenebisacrylamide as a crosslinker, and PSA and Myo as the templates, respectively. The MIP-SPE was specific for the impedimetric sensing of PSA and Myo. After that, a nanocomposite (NCP) was synthesized based on the decorated magnetite nanoparticles with multi-walled carbon nanotube, graphene oxide and specific antibody for PSA (Ab). Then, NCP incubated with (MIP(PSA, Myo)-SPE. The modified electrodes and synthesized nanoparticles were characterized using electrochemical impedance spectroscopy, dynamic light scattering, surface plasmon resonance and scanning electron microscopy. The limits of detections were found to be 5.4 pg mL^-1 and 0.83 ng mL^-1 with the linear dynamic ranges of 0.01-100 and 1-20000 ng mL^-1 for PSA and Myo, respectively. The ability of proposed biosensor to detect PSA and Myo simultaneously with high sensitivity and specificity offers a powerful opportunity for the new generation of biosensors. This dual-analyte specific receptors-based device is highly desired for the integration with lab-on-chip kits to measure a wide panel of biomarkers present at ultralow levels during early stages of diseases progress.

Highly sensitive analysis of four hemeproteins by dynamically-coated capillary electrophoresis with chemiluminescence detector using an off-column coaxial flow interface

Dynamic coating of the surface in capillary electrophoresis with chemiluminescence detection (CE-CL) using an off-column coaxial flow interface for the determination of four hemeproteins was developed. This method is based on the luminol-hydrogen peroxide reaction catalyzed by metalloproteins in alkaline medium. The experimental setup of the CE-CL system with the proposed off-column coaxial interface was evaluated by separation and detection of dopamine and catechol based on inhibition of the luminol-potassium ferricyanide reaction. Highly efficient separation of the two model compounds with symmetrical peak shape and satisfactory reproducibility was achieved by using this interface. In addition, in order to obtain a good resolution for hemeproteins, polyvinylpyrrolidone (PVP) combined with sodium dodecyl sulfate (SDS) were introduced as dynamic modifiers to reduce the unwanted adsorption of non-specific protein. Several parameters affecting the CE separation and CL detection were investigated in detail. Under the optimized conditions, a mixture of the four hemeproteins (horseradish peroxidase (HRP), catalase (Cat), myoglobin (Mb) and cytochrome C (Cyt C)) could be well separated within 20 min. The linear ranges of the four proteins were 5.7 × 10(-8) to 1.1 × 10(-6) mol L(-1) for HRP, 4.0 × 10(-8) to 2.0 × 10(-6) mol L(-1) for Cat, 1.1 × 10(-10) to 5.6 × 10(-8) mol L(-1) for Mb, and 3.8 × 10(-7) to 7.7 × 10(-6) mol L(-1) for Cyt C. The limits of detection (LODs) (S/N = 3) for HRP, Cat, Mb and Cyt C were 2.2 × 10(-8) mol L(-1) (104.5 amol), 1.6 × 10(-8) mol L(-1) (74 amol), 5.6 × 10(-11) mol L(-1) (0.26 amol), and 1.95 × 10(-7) mol L(-1) (0.89 fmol), respectively. The proposed method has been successfully applied to the analysis of low-level Mb in a spiked human urine sample and the recoveries were above 97%. Our primary result demonstrated that the proposed CE-CL method has great potential for Mb determination in clinical diagnosis.

Identification of human brain from a tissue fragment by detection of neurofilament proteins

We developed a method for identifying human brain from a tissue-like fragment by detection of neurofilament protein (NF) using enzyme-linked immunosorbent assay (ELISA). NF was extracted from 0.1 g of organ/tissue homogenized with Tris-HCl buffer (pH 7.2) containing urea, phenylmethylsulfonyl fluoride (PMSF), EDTA and, EGTA. It was necessary to dilute the extract at more than 2(3)-fold to avoid immunosuppression by urea. Positive reaction was always obtained for NF-H in 2(3)-fold diluted extract of brain tissue, however, NF-L and NF-M were not always detected when a brain fragment contained gray matter. Human cerebral white matter could be easily distinguished from other organs/tissues by detecting any of the NF-subunits. Brains of human and some animals could be discriminated by detecting NF-L or NF-M, although the species specificity of NF-H was not good. Our findings suggested that detection of NF-H was more useful than NF-L and NF-M for identifying a brain from a tissue-like fragment. The present ELISA method for NF-H could identify human brain specimens under the following conditions: putrefied at 4 degrees C for up to 3 weeks, dried at 37 degrees C for at least 4 months, heated at 50 degrees C for at least 4 weeks. Our results showed that our method is useful for identification of brain tissue in forensic stain analysis. Two practical cases are described.

A novel method of species identification using human muscle-specific beta-enolase

A novel method of species identification using a sensitive sandwich enzyme immunoassay for human muscle-specific beta-enolase was used to analyze bloodstains and skeletal muscle. Human beta-enolase is detectable in human blood at dilutions up to 3 x 10(3) and human muscle extract (0.1 g/ml) at dilutions up to 5 x 10(6) using a sandwich enzyme immunoassay. The cross-reactivities of both blood and skeletal muscle extracts from other species were 0.01 or less. When human skeletal muscle extract was added in a final concentration of 10 mg/ml, the ratio of beta-enolase to total protein in bloodstains was approximately 1000, whereas the addition of skeletal muscle extract of other species resulted in a ratio of less than 10. Application of this method in a practical case proved that human muscle-specific beta-enolase as a marker for species identification is very effective in forensic practice.

A sandwich enzyme immunoassay for human muscle-specific beta-enolase and its application for the determination of skeletal muscle injury

A sensitive sandwich enzyme immunoassay for human beta-enolase was developed and used to examine beta-enolase in blood or bloodstains as a marker for the determination of skeletal muscle injury. Human beta-enolase was purified from human skeletal muscle, and then an antibody against it was prepared. Polystyrene balls coated with rabbit anti-human beta-enolase IgG were incubated with human beta-enolase and then with anti-human beta-enolase Fab'-peroxidase conjugate. Peroxidase activity bound to the polystyrene balls was assayed by fluorometry using 3-(4-hydroxyphenyl)propionic acid as a hydrogen donor. The detection limit for human beta-enolase was 2.6 pg (30 amol) per assay. The degree of cross-reaction of the sandwich enzyme immunoassay for other organs except for heart (1/10) was about 1/150 or less. Moreover, the localization of beta-enolase in various human tissues was examined by Northern blot analysis, and this confirmed that beta-enolase was expressed only in skeletal and cardiac muscle. Antigenic activity in bloodstains containing beta-enolase was recovered well after storage for 60 days at room temperature. The ratio of beta-enolase to total protein in bloodstains made from non-traumatic blood, nasal hemorrhage and menstrual blood, was within the normal range. In contrast, the ratio of beta-enolase in bloodstains from traumatic blood was obviously elevated (10-30 fold) in comparison with non-traumatic blood. Furthermore, the ratio of beta-enolase was proved to be higher in stains adhering to weapons that had passed through skeletal muscle, indicating that detection of beta-enolase in bloodstains could be used to distinguish crime weapons. These results suggest that beta-enolase is a useful marker for identification of skeletal muscle injury as well as for detecting the origin of bleeding.

Identification of human skin from a tissue fragment by detection of squamous cell carcinoma-related antigen using an enzyme immunoassay

A new method of identifying human skin from a tissue fragment by detection of squamous cell carcinoma-related (SCC) antigen, using an enzyme immunoassay, was developed. When an extract was prepared from 0.1 g human skin homogenized with 1 ml of phosphate buffered saline, this method was able to detect SCC antigen in extracts diluted 10(2)-fold. There was no difference in the detection limit between individuals. Species specificity was good, and there was no cross reaction observed with skins from animals. Our method could also discriminate between skin and other organs or tissues, except for esophagus and lung. A practical case to which this method was applied is presented.