Biomedical subjects

Rodica E Ionescu

Publications and source records attributed to Rodica E Ionescu.

5 recordsLinked to original sources

PubMed2006

Electroenzymatic polypyrrole-intercalator sensor for the determination of West Nile virus cDNA.

The chemical binding of a redox acridone derivative onto a polypyrrole film functionalized by N-hydroxysuccinimide groups provided an electrode capable of anchoring DNA duplex by simple insertion of the grafted acridone intercalator into the dsDNA solution. This electrode was applied for the detection of a ssDNA derived from a West Nile virus sequence. The latter was thus amperometrically detected after its hybridization in solution with a biotinylated complementary oligonucleotide followed by its anchoring and labeling by a glucose oxidase at 1 pg/mL.

Base Sequence↗

PubMed2006

Protease amperometric sensor.

An amperometric biosensor for the detection of trypsin was developed. The latter was based on a two-layer configuration, namely, a polymer-glucose oxidase inner layer and a gelatin outer layer. In the presence of glucose, the enzyme layer produces H2O2 and hence an amperometric signal due to H2O2 electrooxidation was generated by potentiostating the electrode at 0.6 V. The biosensor detects the change in the increase in the maximum current caused by the proteolytic digestion of gelatin, which covers the platinum electrodes, thereby facilitating a speedier access for the glucose substrate to the electrode modified with both poly(pyrrole-alkylammonium) and glucose oxidase molecules. Our biosensor detected low trypsin concentrations down to 42 pM with a response time of approximately 10 min, making it a very sensitive device in the detection of lower trypsin levels with such future putative applications as the diagnosis of pancreatic diseases.

Animals↗

PubMed2005

Manufacturing of nanochannels with controlled dimensions using protease nanolithography.

The feasibility of creating nanometer scale depressions in biological substrates using active enzymes delivered with scanning probe microscopes has been previously demonstrated by us and other groups. Here we present a comprehensive study revealing the dependence of channels dimensions on the parameters of the "writing" process and provide a simple way to precisely control their dimensions. Such nanochannels may be used in nanofluidic biochip applications.

Adsorption↗

PubMed2004

Construction of amperometric immunosensors based on the electrogeneration of a permeable biotinylated polypyrrole film.

The construction of amperometric immunosensors to cholera antitoxin immunoglobulins were shown to have improved sensitivity when the cholera toxin B subunit biorecognition entity was linked to an electrogenerated biotinylated polypyrrole film copolymerized with pyrrole-lactobionamide monomer. The copolymer exhibits greater film permeability than biotinylated polypyrrolic or polyphenolic films for the permeation of electroactive species. Hence, when the presence of the HRP marker of the immunoassay was determined using hydroquinone, the production of electroactive quinone was shown to permeate faster to the electrode, thus providing a faster response time.

Antibodies↗

PubMedDate not supplied

Synthesis and characterization of a pyrrole-alginate conjugate and its application in a biosensor construction.

N-(3-Aminopropyl)pyrrole was covalently coupled with alginate in an aqueous-phase reaction by means of carbodiimide-mediated activation chemistry to provide a pyrrole-alginate conjugate for subsequent use in biosensor applications. The pyrrole-alginate conjugate was quantified by UV spectroscopy at 230 nm, by an HPSEC-MALLS analytical method, as well as by FTIR and 13C NMR spectroscopies. The new pyrrole-alginate conjugate was used for the immobilization of polyphenol oxidase (PPO) onto an electrode surface by physical entrapment resulting from the gellification process and electrochemical polymerization of the pyrrole groups. The efficiency of this cross-linking approach (chemical and electrochemical) was investigated by comparing the amount of enzyme released from polypyrrole-alginate and regular alginate. In addition, biosensors were prepared by entrapment of the PPO in polypyrrole-alginate and regular alginate matrixes and their performance for the amperometric determination of catechol chosen as a model analyte was examined, yielding a sensitivity of 350 and 80 microA M(-1) cm(-2), respectively, for polypyrrole-alginate and alginate biosensors.

Alginates↗