Biomedical subjects

Ruqin Yu

Publications and source records attributed to Ruqin Yu.

8 recordsLinked to original sources

PubMed2004

Immunophenotyping of acute leukemia using an integrated piezoelectric immunosensor array.

Immunophenotyping evaluation is of particular importance for the clinical diagnosis, therapy, and prognosis of acute leukemia. In this paper, an integrated piezoelectric immunosensor array has been developed for the first time to detect the differentiated leukocyte antigens for immunophenotyping of acute leukemia. The probes (crystals) of the array were fabricated with plasma-polymerized n-butylamine film and nanometer-sized gold particles on which the Fab'-SH fragments obtained by the reduction of leukemic lineage-associated monoclonal antibodies (markers) were subsequently immobilized. Investigation results showed that the developed immunosensor array could rapidly identify normal cells from leukemic blasts and define the leukemic blasts within certain phenotypic groups (lineages) by only one analysis of the sample purified or unpurified. It permits the detection of unpurified leukocytes in the dynamic concentration range of 2 orders of magnitude (10(4)-10(6) cells mL(-1)). Up to 17 successive assay cycles with retentive sensitivity were achieved for the probes regenerated with 8 M urea. Moreover, the piezoelectric immunoassay system was applied to evaluate a number of practical specimens with immunophenotyping results in acceptable agreement with those clinically classified. The newly proposed multiparameter analysis technique provides a rapid, simple, and direct alternative tool for clinical immunophenotyping of acute leukemia.

Acute Disease↗

PubMed2004

A piezoelectric immunoagglutination assay for Toxoplasma gondii antibodies using gold nanoparticles.

The serologic detection of anti-Toxoplasma gondii immunoglobulins plays a key role in the clinical diagnosis of Toxoplasmosis. In this paper, a simple, rapid and highly sensitive agglutination-based piezoelectric immunoassay has been firstly developed for directly detecting anti-T. gondii immunoglobulins in infected rabbit serum (IRS) and infected rabbit blood (IRB). The proposed technique is based on that the specific agglutination of antigen-coated gold nanoparticles, averaging 10nm in diameter, in the presence of the corresponding antibody causes a frequency change that is monitored by a piezoelectric device. In contrast to the commonly used piezoelectric assays, it possesses an attractive advantage in that the immobilization of antibody or antigen on the crystal is unnecessary. Use of a newly prepared sensing probe which was modified by a plasma-polymerized film (PPF) of n-butyl amine and further by a heparin layer resulted in a response-enhanced immunoagglutination and a high compatibility of the probe with biological samples. An appropriate reagent consisting of 1% normal rabbit serum (NRS) and 0.1% bovine serum albumin (BSA) for diluting the analytes were verified in counteracting the background interference of assay. Moreover, an optimization of assay medium composition with the addition of poly(ethylene glycol) (PEG) serving as immunoagglutination rate and sensitivity enhancer was investigated in detail. It is found that the developed immunoagglutination assay system is sensitive to dilution ratio of anti-T. gondii antibody as low as 1:5500. Analytical results of several specimens obtained using the developed technique are in satisfactory agreement with those given by the ELISA method, implying a promising alternative approach for detecting anti-T. gondii antibodies in the clinical diagnosis.

Agglutination Tests↗

PubMed2004

A protein A-based orientation-controlled immobilization strategy for antibodies using nanometer-sized gold particles and plasma-polymerized film.

A novel protein A (PA)-based strategy for the orientation-controlled immobilization of antibodies using nanometer-sized gold (Nano-gold) particles and an amine-terminated plasma-polymerized film (PPF) has been proposed. A quartz crystal microbalance was fabricated, accordingly, coupling with haptoglobin (HP) antibody followed by HP immunoassay, as a model test system. The crystal was modified with plasma-polymerized n-butyl amine film to deposit Nano-gold particles and PA, on which HP antibodies were immobilized. The surface topology of the as-prepared crystal was characterized by use of scanning electron microscopy. In contrast to the traditional flat gold surface, the assembled Nano-gold particle monolayer could allow PA molecules bound with higher bioactivity and loading amount (density), achieving better antibody-binding capabilities. Results indicate that immunosensors prepared using the developed PPF-Nano-gold-PA binding procedure exhibit increased analytical performance compared with those produced using the direct PA binding procedure and the PPF-based glutaraldehyde cross-linking procedure. A HP serum concentration as low as 0.41 nM can be determined by this new system. Regenerated simply by rinsing in the acid buffer, the proposed sensor can achieve up to 11 assay cycles without significant loss of sensitivity.

Animals↗

PubMed2003

A novel biosensing interfacial design produced by assembling nano-Au particles on amine-terminated plasma-polymerized films.

A novel biosensing interfacial design strategy has, for the first time, been produced by assembling nano-Au particles on amine-terminated plasma-polymerized films (PPF). A quartz-crystal microbalance (QCM) as a model transducer was deposited with PPF of n-butylamine by use of a glow discharge and then treated with nano-Au particles. The kinetic assembly process and conditions were studied using the real-time-output device and the surface topology of the resulting crystal was characterized by atomic force microscopy (AFM) imaging. Based on analysis of the experimental data, including the association constant of Au-amine interaction, the assembly mechanism is considered to be partly or even mainly chemical adsorption. Moreover, immobilization of anti-human IgM antibody (IgM Ab), as an example, on the developed PPF-Au interface was investigated. It was found that antibody molecules immobilized by the proposed procedure had higher immunological activity than those immobilized by the conventional glutaraldehyde (GLU) cross-linking procedure or the direct gold-attachment procedure. The newly developed sensor had a better response, with a detection limit of IgM concentration as low as approximately 1.00 microg mL(-1). In particular, the extremely high stability of both PPF and nano-Au monolayer formulated allows the designed biosensing interface to withstand harsh regeneration treatment, making it reusable.

Biosensing Techniques↗

PubMed2003

A chaotic approach to maintain the population diversity of genetic algorithm in network training.

The concept of chaos being radically different from statistical randomness is introduced into chemometrics research. The chaotic system that is deterministic with underlying patterns and inherent ability in searching the space of interest has been employed to improve the performance of chemometric algorithms. In this paper, a chaotic mutation is introduced into the genetic algorithm (GA) which is used for artificial neural network (ANN) training. The chaotic algorithm is very efficient in maintaining the population diversity during the evolution process of GA. The proposed algorithm CGANN has been testified by prediction of vibrational frequencies of octahedral hexahalides from some selected molecular parameters.

Algorithms↗

PubMed2002

Genetic training of network using chaos concept: application to QSAR studies of vibration modes of tetrahedral halides.

The chaotic dynamical system is introduced in genetic algorithm to train ANN to formulate the CGANN algorithm. Logistic mapping as one of the most important chaotic dynamic mappings provides each new generation a high chance to hold GA's population diversity. This enhances the ability to overcome overfitting in training an ANN. The proposed CGANN has been used for QSAR studies to predict the tetrahedral modes (nu(1)(A1) and nu(2)(E)) of halides [MX(4)](epsilon). The frequencies predicted by QSAR were compared with those calculated by quantum chemistry methods including PM3, AM1, and MNDO/d. The possibility of improving the predictive ability of QSAR by including quantum chemistry parameters as feature variables has been investigated using tetrahedral tetrahalide examples.

Algorithms↗

PubMed2002

A piezoelectric immunoassay based on self-assembled monolayers of cystamine and polystyrene sulfonate for determination of Schistosoma japonicum antibodies.

A piezoelectric immunosensor based on an improved immobilization strategy combining self-assembled monolayers (SAM) of cystamine (Cys) and polystyrene sulfonate (PSS) has been developed for the determination of Schistosoma japonicum antibodies (SjAb) in rabbit serum. Cys SAM were first applied to the gold electrode surface of the crystal, serving as a positively-charged base. Schistosoma japonicum antigen (SjAg) was then electrostatically immobilized on the crystal by means of a negatively-charged PSS layer. When sealed by use of an appropriately selected blocking reagent for BSA and normal rabbit serum (NRS), non-specific adsorption could be substantially reduced. The immunosensor was used to determine SjAb in optimized buffer medium with addition of poly(ethylene glycol) (PEG), which served as an immunoreaction enhancer. It was shown experimentally that SjAg immobilized by the Cys-PSS adsorption procedure had higher immunological activity or binding efficiency than those immobilized by the glutaraldehyde (GLU) binding or direct attachment procedures. The immunosensor developed had satisfactory sensitivity and detection limit, and regeneration of the piezoelectric quartz-crystal was easy. Analytical results obtained with infected rabbit serum samples indicated that the proposed immunosensor is a promising alternative for qualitative and quantitative determination of SjAb in clinical diagnosis of infection with Schistosoma japonicum.

Adsorption↗

PubMed2002

Renewable urea sensor based on a self-assembled polyelectrolyte layer.

A renewable urea sensor based on a carboxylic poly(vinyl chloride) (PVC-COOH) matrix pH-sensitive membrane has been proposed, in which a positively charged polyelectrolyte layer is first constructed by using a self-assembly technique on the surface of a PVC-COOH membrane, and urease, with negative charges, is then immobilized through electrostatic adsorption onto the PVC-COOH membrane, by controlling the pH of the urease solution below its isoelectric point. The response characteristics of the PVC-COOH pH-sensitive membrane and the effects of experimental conditions have been investigated in detail. Compared with conventional covalent immobilization, the urea sensor made with this self-assembly immobilization shows significant advantage in terms of sensitivity and ease of regeneration. The potential responses of the urea sensor with self-assembly immobilization increase with the urea concentration over the concentration range 10(-5) - 10(-1) mol l(-1), and the detection limit is 0.028 mmol(-1). Moreover, this type of urea sensor can be repeatedly regenerated by using a simple washing treatment with 0.01 mol l(-1) NaOH (containing 0.5 mol l(-1) NaCl) and 0.01 mol l(-1) HCl. The urease layers and the polyelectrolyte layers on the PVC-COOH membrane are removed, the potential response of the sensor to urea solutions of different concentrations returns nearly to zero, and another assembly cycle of urease and polyelectrolyte can then be carried out.

Biosensing Techniques↗