In vitro, in vivo and post explantation testing of glucose-detecting biosensors: Current methods and recommendations

Abstract

To date, there have been a number of cases where glucose sensors have performed well over long periods of implantation; however, it remains difficult to predict whether a given sensor will perform reliably, will exhibit gradual degradation of performance, or will fail outright soon after implantation. Typically, the literature emphasizes the sensor that performed well, while only briefly (if at all) mentioning the failed devices. This leaves open the question of whether current sensor designs are adequate for the hostile in vivo environment, and whether these sensors have been assessed by the proper regimen of testing protocols. This paper reviews the current in vitro and in vivo testing procedures used to evaluate the functionality and biocompatibility of implantable glucose sensors. An overview of the standards and regulatory bodies that govern biomaterials and end product device testing precedes a discussion of up-to-date invasive and non-invasive technologies for diabetes management. Analysis of current in vitro, in vivo, and then post explantation testing is presented. Given the underlying assumption that the success of the sensor in vitro foreshadows the long-term reliability of the sensor in the human body, the relative merits of these testing methods are evaluated with respect to how representative they are of human models.

Optical properties of hydrogels filled with dispersed nanoparticles

“…In this case, we took into account that mass concentration of dispersed phase C (g/cm 3 ) can be presented as CvVd =⋅⋅, where d is the density of dispersed phase, V is the volume of one spherical particle V=4/3πr 3 …”

“…Polymeric materials with specific stimuli responsive behavior are widely used for medical and biotechnological applications [1][2][3][4]. In particular, polymeric hydrogel systems have attracted great interest due to their soft and flexible consistency and their ability to absorb large amounts of water, keeping at the same time their three-dimensional stability [5,6].…”

A silicon nanoparticle-based polymeric nano-composite material for glucose sensing

“…CV2 and CV3 were obtained using the same electrode under differ ent conditions. CV2 was obtained in 4 mM glucose while CV3 was obtained a solution that contained 4 mM glucose and the physio logical level [1,19] of 1 mM of each of the interfering agents, AA, UA and AP. It is obvious that CV2 coincides with CV3.…”

“…glucose oxidase (GOx). as sensing element [1]. The primary issue of using GOx as sensing element is the inherent instability of the enzyme.…”

Biosensors for health applications

“…Non-invasive glucose sensing is the ultimate goal of glucose monitoring and the main approaches being pursued for glucose sensor development are: near infrared spectroscopy, excreted physiological fluid (tears, sweat, urine, saliva) analysis, microcalorimetry, enzyme electrodes, optical sensors, sonophoresis and iontophoresis, both of which extract glucose from the skin (Koschwanez & Reichert, 2007;Beauharnois et al, 2006;Chu et al, 2011). Despite the relative ease of use, speed and minimal risk of infection involved with infrared spectroscopy, this technique is hindered by the low sensitivity, poor selectivity, frequently required calibrations, and difficulties with miniaturization.…”