Jeff T. Suri

Boronic acid substituted viologen based optical sugar sensors: modulated quenching with viologen as a method for monosaccharide detection ☆

Abstract In our search for an optical glucose sensor we have found that the combination of pyranine 1 and a boronic acid substituted benzyl viologen (o-BBV, 2 ) signals monosaccharides in the range of 0–1800 mg/dL. The quenching ability of o-BBV is modulated upon sugar binding, which in turn alters the fluorescence of pyranine. The system utilizes a dye that is active in the visible spectrum, operates in aqueous solution at pH 7.4, and is highly sensitive to glucose in the physiological range.

Evaluation of Pyranine Derivatives in Boronic Acid Based Saccharide Sensing: Significance of Charge Interaction Between Dye and Quencher in Solution and Hydrogel

In an ongoing program to synthesize a glucose sensing polymer that could be used for real time glucose monitoring in vivo, we have been exploring the use of boronic acid functional viologens as glucose responsive quenchers for fluorescent dyes. The present study focuses on the effect of ionic interactions between pyranine or its various sulfonamide derivatives and the viologen quenchers. Dyes bearing anionic groups were quenched more efficiently when compared to dyes with nonionic substituents. The anionic dyes in conjunction with the cationic quenchers exhibited a broader range of glucose response both in solution and when immobilized in a hydrogel. The interaction of glucose with the sensing components was similar whether they are soluble or immobilized.

Enantioselective reduction of aryl ketones using LiBH4 and TarB-X: a chiral Lewis acid

Abstract High enantioselectivities are obtained using a tartaric acid-derived boronate ester in combination with lithium borohydride for asymmetric reduction of aryl ketones. The chiral Lewis acid, TarB-X, is easily prepared in 1 h, and the resulting alcohols are obtained in enantiomeric excesses of 88–99%.

Use of a Novel Fluorescent Glucose Sensor in Volunteer Subjects with Type 1 Diabetes Mellitus

Background: Stress hyperglycemia in the critically ill has been found to be associated with increased morbidity and mortality. Studies have found significant improvements in morbidity and mortality in postsurgical patients whose glucose levels were closely maintained in the euglycemic range. However, subsequent studies, in particular the Normoglycemia in Intensive Care Evaluation and Survival Using Glucose Algorithm Regulation (NICE-SUGAR) study, found no improvement in subjects with tight glycemic control. In addition to differences in protocol design, patients in the tight glycemic control arm of the NICE-SUGAR study experienced high rates of hypoglycemia compared with other studies. One interpretation of the NICE-SUGAR study results is that it is difficult to achieve normal glycemia in critically ill patients with existing glucose monitoring technology. The purpose of the study reported here was to evaluate the safety and performance of a continuous intravascular glucose sensor that could be used in the future in critically ill patients. Methods: A first-generation prototype of an intravascular continuous glucose sensor was evaluated in 29 volunteer subjects with type 1 diabetes mellitus. The sensor operates on the principle of quenched fluorescence. The fluorescent emission from the sensor chemistry is nonlinear, resulting in improved accuracy in the hypoglycemic range. The duration of each study was 8 hours. Sensor output was compared with temporally correlated reference measurements made from venous samples on a laboratory glucose analyzer. Results: Data were obtained from 18 of the 29 subjects in the study. Data were analyzed retrospectively using a factory calibration plus a one-point in vivo calibration. The mean absolute relative difference was 7.97%, and 95.1% of all the points were in zone A of the Clarke error grid. Conclusions: This pilot study was the first use in human subjects of a prototype of the GluCath Intravascular Continuous Glucose Monitoring System (GluCath System). The GluCath System is based on a novel fluorescent sensor chemistry. The study found the GluCath System had a high level of accuracy as compared with a laboratory reference analyzer.

N,N′-Di­benzyl-4,7-phenanthrolinium dibromide methanol solvate

The structure of the phenanthroline-derived viologen, C26H22N22+·2Br−·CH3OH, as the methanol solvate, was determined as part of a fluorescence-quenching study. There is intermolecular π–π stacking of the phenanthroline and benzyl arms as well as methanol hydrogen bonding to a bromide.

N-[2-(Hydro­xy­methoxy­boryl)­benzyl]-4,7-phenanthrolinium bromide methanol solvate

The structure of the phenanthroline-derived boronic acid viologen, C20H18BN2O2+·Br−·CH3OH, as a methanol solvate, was determined as part of a fluorescence quenching study. There is –π stacking of the phenanthroline rings and hydrogen bonding involving Br− ions.