Glucose-Sensitive Nanoassemblies Comprising Affinity-Binding Complexes Trapped in Fuzzy Microshells

Abstract

A new design for glucose monitoring with "smart" materials based on self assembly, competitive binding, and resonance energy transfer (RET) is presented. The basic transduction principle is changing RET efficiency from fluorescein isothiocyanate (FITC) to tetramethylrhodamine isothiocyanate (TRITC), as FITC-dextran is displaced from TRITC-Concanavalin A (Con A) with the addition of glucose. Nanoscale fabrication by self-assembly of Con A/dextran into multilayer films, followed by polymer multilayers. The advantages of this approach include physical localization and separation of sensing molecules from the environment via entrapment of the biosensor elements in a semi-permeable polymeric shell, and only functional molecules are included in the sensors. To realize these nanostructures, dissolvable resin microparticles were coated with FITC-dextran+TRITC-Con A multilayers, followed by polyelectrolyte multilayers, and the core particles were then dissolved to yield hollow capsules. The nanoassembly process was studied using microbalance mass measurements, fluorescence spectroscopy, confocal fluorescence microscopy, and zeta-potential measurements. The key findings are that the specific binding between Con A and dextran can be used to deposit ultrathin multilayer films, and these exhibit changing RET in response to glucose. Fluorescence spectra of a microcapsules exhibited a linear, glucose-specific, 27% increase in the relative fluorescence of FITC over the 0-1800 mg/dL range. These findings demonstrate the feasibility of using self-assembled microcapsules as optical glucose sensors, and serve as a basis for work toward better understanding the properties of these novel materials.

Multilayer nanoencapsulation: A nanomedicine technology for diabetes research and management

“…Microvesicles created by LBL encapsulation and containing fluorescence-based glucose sensors have been described by our own group [2,10], as well as McShane et al [11][12][13][14][15]. In general, hollow-vesicle sensors can be formed by LBL deposition around a removable template such as calcium carbonate which can then dissolved (e.g.…”

“…Several fluorescence-based glucose sensing assays have been incorporated into multilayer nanocapsules, operating as either competitive or non-competitive systems. In competitive systems, there is a change in fluorescence resonance energy transfer (FRET) when glucose binds to a fluorescent-labelled receptor such as tetramethyl rhodamine isothiocyanate labelled concanavalin A (FRET acceptor), in competition with a fluorescent glucose analogue such as fluorescein isothiocyanate-labelled dextran (FRET donor) [12]. Other competitive systems use apo glucose oxidase (glucose oxidase with the prosthetic group removed) as the glucose receptor, labelled with a variety of acceptors, together with dextran labelled with one of several donors [13,14].…”

Fiber-Coupled Fluorescence Affinity Sensor for 3-Day in Vivo Glucose Sensing

“…Over the last several years, research into fluorescence affinity sensors (FAS) for glucose detection has steadily gained acceptance among scientists and clinicians through the introduction of a number of improved glucosesensitive assays based on either glucose-specific protein concanavalin A (Con A) [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] or borate-based artificial glucose-specific receptors. 23,24 Independent of the type of receptor, there are several intrinsic advantages of a fluorescence affinity sensor over electrode-enzymatic sensors in terms of practicality for in vivo sensing.…”

Assembling of xyloglucans and lectin onto si wafers and onto amino-terminated surfaces

“…for cell adhesion and recognition of pathogens by specific surface carbohydrates by the immune system, and can be useful probes in studying carbohydrates of cell surfaces. Apart from their physiological importance, carbohydrates and lectins are also expected to become important tools for recognition of bioanalytes 11 -1 , Sigma C2010, USA), was used without any purification. Silicon wafers (Si/SiO 2 ) purchased from SiliconQuest, USA, were rinsed in a standard manner 13,14 prior to the XG adsorption.…”