Sefi Vernick

Optical and Electrical Interfacing Technologies for Living Cell Bio-Chips

Whole-cell bio-chips for functional sensing integrate living cells on miniaturized platforms made by micro-system-technologies (MST). The cells are integrated, deposited or immersed in a media which is in contact with the chip. The cells behavior is monitored via electrical, electrochemical or optical methods. In this paper we describe such whole-cell biochips where the signal is generated due to the genetic response of the cells. The solid-state platform hosts the biological component, i.e. the living cells, and integrates all the required micro-system technologies, i.e. the micro-electronics, micro-electro optics, micro-electro or magneto mechanics and micro-fluidics. The genetic response of the cells expresses proteins that generate: a. light by photo-luminescence or bioluminescence, b. electrochemical signal by interaction with a substrate, or c. change in the cell impedance. The cell response is detected by a front end unit that converts it to current or voltage amplifies and filters it. The resultant signal is analyzed and stored for further processing. In this paper we describe three examples of whole-cell bio chips, photo-luminescent, bioluminescent and electrochemical, which are based on the genetic response of genetically modified E. coli microbes integrated on a micro-fluidics MEMS platform. We describe the chip outline as well as the basic modeling scheme of such sensors. We discuss the highlights and problems of such system, from the point of view of micro-system-technology.

Directed Metallization of Single-Enzyme Molecules With Preserved Enzymatic Activity

A new method for the fabrication of molecular, water-soluble, and biologically active enzyme-metal hybrids was designed and its feasibility demonstrated. The method is based on the display of nucleation sites directing a subsequent electroless deposition of palladium and other metals to the enzymes surface. The process is carried out under mild physiological conditions, enabling the preservation of enzymatic activity and water solubility. The feasibility of the new method was demonstrated by using the enzyme glucose oxidase and palladium combination as the first model system. The glucose oxidase-palladium hybrid thus obtained retained their solubility and enzymatic glucose oxidation capabilities. Hybrids immobilized on platinum electrodes exhibited ldquonanowiringrdquo and effective direct electron transfer from the enzyme catalytic site to the electrode. The new enzyme-metal hybrids thus obtained may be readily incorporated into miniaturic biosensors and biochips, used as novel antibacterial agents or as markers for improved in vivo imaging. Furthermore, the methodology developed may be readily extended to a series of metal coatings on the surface of biologically active proteins.

Sa1865 Colon Cancer Diagnosis by Multiple Biomarker Electrobiochemical Detection in Biopsy Slices

Back ground: Deep enteroscopy for the evaluation and treatment of small bowel pathology has undergone significant technology advancements over the last ten years. Studies directly comparing single (SBE) and double balloon enteroscopy (DBE) with spiral enteroscopy (SE) are few but suggest that the three techniques are comparable. Method: Retrospective review of Spirus® small bowel endoscopy cases over 12 months Results: A single experienced endoscopist completed all cases. The patient characteristics are listed in Table 1. Two patients had strictures (one was dilated) and one had multiple arteriovenous malformations (coagulated with Argon Plasma). Two patients experienced complications. Case 1: A 77 year old female with remote radiation treatment for endometrial carcinoma being evaluated for anemia had several slightly narrowed areas; all judged to be spacious enough to accommodate the overtube except one. The last area appeared tight and the overtube was unlocked as soon as it engaged the location and the scope alone was advanced further. Surprisingly the cecum was reached without difficulty. Upon endoscope withdrawal, bleeding was noted and a perforation was suspected. A tense abdomen was decompressed with a needle, rapidly stabilizing a low blood pressure. Perforation was identified and the segment with several strictures was resected. Case 2: A 44 year old female with cirrhosis secondary to primary sclerosing cholangitis status post hepaticojejunostomy had recurrent anastomotic strictures. On SE assisted ERCP, a perforation was suspected on radiography. ERCP was completed and exam was continued under water without gas insufflation. The perforation was found on the biliary limb and was not favorable for endoclip closure. The spilled intestinal contents were suctioned and pneumoperitoneum was decompressed allowing the patient to be comfortable and stable until laparotomy. A guidewire was placed endoscopically which allowed easy identification of the site during surgery (Figure 1). Conclusion: Patients with known or occult small bowel strictures and surgically altered anatomy with possible adhesional fixation may be at a higher risk of complications and we suggest caution with use of SE in these scenarios. When perforations occur, early recognition and immediate management are of benefit. Despite suffering complications, both patients benefited from their procedures. In case 1, the resection of the diseased intestine led to resolution of anemia. In Case 2, the bile duct stricture was successfully treated and she was bridged to transplant. Table 1: Patient characteristics