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Elektrocheminiai matavimai atlikti kambario temperatūroje, trijų elektrodų celėje, kuri matavimų metu buvo laikyta tamsoje (FMS jautrus šviesai). Darbiniu elektrodu panaudotas sukurtas iš mielių ląstelių biojutiklis, pagalbiniu Pt – elektrodas ir sidabro chloridinis – kaip palyginamasis elektrodas. Potenciodinaminiu bei potenciostatiniu metodais ištirti įvairių modifikacijų jutikliai. Gauti duomenis fiksuojami kompiuteriu programoje BAS Epsilon EC-2000-XP ( Ver.1,50,69_XP) ir analizuojami. Parinkome labiausiai tinkantį jutiklio modifikacijos būdą L-pieno rūgšties nustatymui ir įvertinome įvairių veiksnių įtaką oksidacinių srovių stipriui bei rezultatų stabilumui. Ištyrėme biojutiklio veikimą natūralioje aplinkoje. Kaip natūralius L-pieno rūgšties šaltinius panaudojome tokius pieno produktus, kaip jogurtas ir kefyras. Tyrimų metu nustatyta, kad optimaliausios sąlygos biologinio jutiklio veikimui yra: Econst.0 V, sausos mielių ląstelės iš suspensijos adsorbuotos ant jutiklio pavir��iaus, 0,2 mmol/l FMS tirpalas fosfatiniame buferyje, pH7,2. Darbo privalumas yra tas, kad jutiklių kūrimui panaudotas pigus fermento flavocitochromo b2 šaltinis – mielių ląstelės. Trūkumas – stiprus triukšmingumas, kas padidina jutiklio nustatymo ribas ( jutiklis tampa jautrus kitiems substratams) ir ilgas laikas, kol pasiekiamas stabilus rezultatas. / Electrochemical measurements were performed in a three-electrode cell arranged with a magnetic stirrer. Carbon paste electrode served as a working electrode. Platinum wire and Ag/ AgCl, 3 NaCl were, respectively, counter and reference electrodes. All measurements were performed with BAS-Epsilon Bioanalytical system. This work presents investigation of carbon paste electrodes modified with commercially available yeasts as amperometric biosensors for lactic acid using a mediator phenazine methosulphate (PMS). Sensitivity to lactic acid was tested using various configurations of the electrodes (yeast layer on the top of the electrode, yeast in the bulk carbon paste, PMS in solution or in the bulk carbon paste). The optimal operational conditions of the electrodes were: an operating potential 0.0 V, solution pH 7.2, concentration of phenazine methosulphate in solution 0.2 mmol/l, and yeast layer on the top of the electrode. The suitability of yeast-modified electrodes for determination of L-lactic acid in milk and dairy products such as kefir and yoghurt was also tested. The advantages of the electrodes were the simple preparation from the cheap source of the enzyme flavocytochrome b2. The disadvantages of the electrodes were long time to achieve reproducible results, high noise level, thus, high detection limit and sensitivity to other metabolites.

No description available.

Graphene is a single layer of carbon atoms, laid out in a hexagonal lattice. The material has remarkable properties that opened up several new research areas since its discovery in 2004. One promising field is graphene based biosensors, where researchers hope to create new devices that are smaller, cheaper and more reliable than those based on today’s technology. Among several manufacturing methods, graphene grown on silicon carbide is one of the promising ones for biosensing. A chip design has been developed in order to support research into graphene on silicon carbide as a base material for biosensors. Along with the chip, a holder for electrochemical measurements has been designed and an investigation into the requirements of a custom measurement device for the sensor has been undertaken.

Thesis (Ph.D.)--Tufts University, 1999. / Adviser: David R. Walt. Submitted to the Dept. of Chemistry. Includes bibliographical references (leaves 233-253). Access restricted to members of the Tufts University community. Also available via the World Wide Web;

Thesis (Ph.D.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 121-142)

Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references.

Thesis (Ph. D.)--Georgia State University, 2007. / Title from file title page. Melody Moore, committee chair; Detmar Straub, Veda Storey, Bruce Walker, committee members. Electronic text (166 p. : ill. (some col.)) : digital, PDF file. Description based on contents viewed Nov. 5, 2007. Includes bibliographical references (p. 160-164).

Thesis (M. Phil.)--University of Hong Kong, 2008. / Also available in print.