Biomedical subjects

Bilha Willner

Publications and source records attributed to Bilha Willner.

6 recordsLinked to original sources

PubMed2006

Nanoparticle-enzyme hybrid systems for nanobiotechnology.

Biomolecule-nanoparticle (NP) [or quantum-dot (QD)] hybrid systems combine the recognition and biocatalytic properties of biomolecules with the unique electronic, optical, and catalytic features of NPs and yield composite materials with new functionalities. The biomolecule-NP hybrid systems allow the development of new biosensors, the synthesis of metallic nanowires, and the fabrication of nanostructured patterns of metallic or magnetic NPs on surfaces. These advances in nanobiotechnology are exemplified by the development of amperometric glucose sensors by the electrical contacting of redox enzymes by means of AuNPs, and the design of an optical glucose sensor by the biocatalytic growth of AuNPs. The biocatalytic growth of metallic NPs is used to fabricate Au and Ag nanowires on surfaces. The fluorescence properties of semiconductor QDs are used to develop competitive maltose biosensors and to probe the biocatalytic functions of proteases. Similarly, semiconductor NPs, associated with electrodes, are used to photoactivate bioelectrocatalytic cascades while generating photocurrents.

Animals↗

PubMed2006

Electrical contacting of redox proteins by nanotechnological means.

Redox enzymes in bioelectronic devices usually lack direct electrical contact with electrodes, owing to the spatial separation of their redox centers from the conductive surfaces by the protein shells. The reconstitution of apo-enzymes on cofactor-functionalized nanostructures associated with electrodes provides a means to align the biocatalysts on the conductive surface and to electrically contact redox enzymes with electrodes. The reconstitution of apo-enzymes on cofactor-functionalized gold nanoparticles or carbon nanotubes has led to effective electrical communication between the redox proteins and the electrodes. Alternatively, the reconstitution of redox enzymes on molecular wires that enable electron tunneling or dynamic charge shuttling represent supramolecular biocatalytic nanostructures exhibiting electrical contact. The bioelectrocatalytic activities of the electrically wired reconstituted enzymes on electrodes have allowed the development of amperometric biosensors and biofuel cell elements.

Biosensing Techniques↗

PubMed2006

Integrated nanoparticle-biomolecule systems for biosensing and bioelectronics.

The similar dimensions of biomolecules such as enzymes, antibodies or DNA, and metallic or semiconductor nanoparticles (NPs) enable the synthesis of biomolecule-NP hybrid systems where the unique electronic, photonic and catalytic properties of NPs are combined with the specific recognition and biocatalytic properties of biomolecules. The unique functions of biomolecule-NP hybrid systems are discussed with several examples: (i) the electrical contacting of redox enzymes with electrodes is the basis for the development of enzymatic electrodes for amperometric biosensors or biofuel cell elements. The reconstitution of the apo-glucose oxidase or apo-glucose dehydrogenase on flavin adenine dinucleotide (FAD)-functionalized Au NPs (1.4 nm) associated with electrodes, or on pyrroloquinoline quinone (PQQ)-functionalized Au NPs (1.4 nm) associated with electrodes, respectively, yields electrically contacted enzyme electrodes. The aligned, reconstituted enzymes on the electrode surfaces reveal effective electrical contacting, and the glucose oxidase and glucose dehydrogenase reveal turnover rates of 5000 and 11,800 s(-1), respectively. (ii) The photoexcitation of semiconductor nanoparticles yields fluorescence with a wavelength controlled by the size of the NPs. The fluorescence functions of semiconductor NPs are used to develop a fluorescence resonance energy transfer (FRET) assay for nucleic acids, and specifically, for analyzing telomerase activity in cancer cells. CdSe-ZnS NPs are functionalized by a primer recognized by telomerase, and this is elongated by telomerase extracted from HeLa cancer cells in the presence of dNTPs and Texas-red-functionalized dUTP. The dye integrated into the telomers allows the FRET process that is intensified as telomerization proceeds. Also, the photoexcited electron-hole pair generated in semiconductor NPs is used to generate photocurrents in a CdS-DNA hybrid system associated with an electrode. A redox-active intercalator, methylene blue, was incorporated into a CdS-duplex DNA monolayer associated with a Au electrode, and this facilitated the electron transfer between the electrode and the CdS NPs. The direction of the photocurrent was controlled by the oxidation state of the intercalator. (iii) Biocatalysts grow metallic NPs, and the absorbance of the NPs provides a means to assay the biocatalytic transformations. This is exemplified with the glucose oxidase-induced growth of Au NPs and with the tyrosinase-stimulated growth of Au NPs, in the presence of glucose or tyrosine, respectively. The biocatalytic growth of the metallic NPs is used to grow nanowires on surfaces. Glucose oxidase or alkaline phosphatase functionalized with Au NPs (1.4 nm) acted as 'biocatalytic inks' for the synthesis of metallic nanowires. The deposition of the Au NP-modified glucose oxidase, or the Au NP-modified alkaline phosphatase on Si surfaces by dip-pen nanolithography led to biocatalytic templates, that after interaction with glucose/AuCl4- or p-aminophenolphosphate/Ag+, allowed the synthesis of Au nanowires or Ag nanowires, respectively.

Biosensing Techniques↗

PubMed2006

Biomolecule-nanoparticle hybrids as functional units for nanobiotechnology.

Biomolecule-metal or semiconductor nanoparticle (NP) hybrid systems combine the recognition and catalytic properties of biomolecules with the unique electronic and optical properties of NPs. This enables the application of the hybrid systems in developing new electronic and optical biosensors, to synthesize nanowires and nanocircuits, and to fabricate new devices. Metal NPs are employed as nano-connectors that activate redox enzymes, and they act as electrical or optical labels for biorecognition events. Similarly, semiconductor NPs act as optical probes for biorecognition processes. Double-stranded DNA or protein chains that are modified with metallic nanoclusters act as templates for the synthesis of metallic nanowires. The nanowires are used as building blocks to assemble nano-devices such as a transistor or a nanotransporter.

Biotechnology↗

PubMed2006

Biomolecule-nanoparticle hybrid systems for bioelectronic applications.

Recent advances in nanobiotechnology involve the use of biomolecule-nanoparticle (NP) hybrid systems for bioelectronic applications. This is exemplified by the electrical contacting of redox enzymes by means of Au-NPs. The enzymes, glucose oxidase, GOx, and glucose dehydrogenase, GDH, are electrically contacted with the electrodes by the reconstitution of the corresponding apo-proteins on flavin adenine dinucleotide (FAD) or pyrroloquinoline quinone (PQQ)-functionalized Au-NPs (1.4 nm) associated with electrodes, respectively. Similarly, Au-NPs integrated into polyaniline in a micro-rod configuration associated with electrodes provides a high surface area matrix with superior charge transport properties for the effective electrical contacting of GOx with the electrode. A different application of biomolecule-Au-NP hybrids for bioelectronics involves the use of Au-NPs as carriers for a nucleic acid that is composed of hemin/G-quadruplex DNAzyme units and a detecting segment complementary to the analyte DNA. The functionalized Au-NPs are employed for the amplified DNA detection, and for the analysis of telomerase activity in cancer cells, using chemiluminescence as a readout signal. Biomolecule-semiconductor NP hybrid systems are used for the development of photoelectrochemical sensors and optoelectronic systems. A hybrid system consisting of acetylcholine esterase (AChE)/CdS-NPs is immobilized in a monolayer configuration on an electrode. The photocurrent generated by the system in the presence of thioacetylcholine as substrate provides a means to probe the AChE activity. The blocking of the photocurrent by 1,5-bis(4-allyldimethyl ammonium phenyl)pentane-3-one dibromide as nerve gas analog enables the photoelectrochemical analysis of AChE inhibitors. Also, the association CdS-NP/double-stranded DNA hybrid systems with a Au-electrode, and the intercalation of methylene blue into the double-stranded DNA, generates an organized nanostructure of switchable photoelectrochemical functions. Electrochemical reduction of the intercalator to the leuco form, -0.4 V vs. SCE, results in a cathodic photocurrent as a result of the transfer of photoexcited conduction-band electrons to O(2) and the transport of electrons to the valance-band holes by the reduced intercalator units. The oxidation of the intercalator, E 0 V (vs. SCE), yields in the presence of triethanolamine, TEOA, as sacrificial electron donor, an anodic photocurrent by the transport of conduction-band electrons, through intercalator units, to the electrodes, and filling the valance-band holes with electrons supplied by TEOA. The systems reveal potential-switchable directions of the photocurrents, and reveal logic gate functions.

Animals↗

PubMed2002

Functional biosensor systems via surface-nanoengineering of electronic elements.

Bioelectronics is a progressing interdisciplinary research field that involves the integration of biomaterials with electronic transducers such as electrodes, field-effect transistors or piezoelectric crystals. Surface engineering of biomaterials such as enzymes, antigen-antibodies or DNA on the electronic supports controls the electrical properties of the biomaterial/transducer interface and enables the electronic transduction of biorecognition events, or biocatalyzed transformation, on the transducers. The development of biosensor systems of tailored sensitivities and specificities represents a major advance in bioelectronics.

Antigen-Antibody Reactions↗