title: Glucose response of dissolved-core alginate microspheres: towards a continuous glucose biosensor.
abstract: Microparticle optical sensors hold potential as implantable smart materials for in vivo analysis. In this work, the reversible response of dissolved-core alginate microspheres containing a homogeneous fluorescence resonance energy transfer (FRET)-based competitive binding assay for glucose was evaluated. The layer-by-layer self assembly technique was used to deposit multilayered nanofilm coatings on the alginate microspheres containing the assay, thereby stabilizing the sensor system when the alginate was de-crosslinked. The response to glucose was then determined in DI water and simulated interstitial fluid (SIF) using a flow cell to establish controlled, dynamic flow conditions for demonstrating reversibility. The glucose sensitivity under dynamic conditions was estimated to be 0.52%/mM glucose in DI water and 0.6%/mM glucose in simulated interstitial fluid; in both cases, the analytical response range was 0-30 mM glucose, covering both physiological (normoglycemia) and pathophysiological range (hyperglycemia and hypoglycemia). The sensor demonstrated a repeatable and reproducible response when tested over a period of one month, under dynamic flow conditions. Finally, in vitro cytotoxicity assays performed with L929 mouse fibroblast cell lines suggested that the dissolved-core alginate microsphere sensor system with nanofilm coating has sufficient biocompatibility for use as implantable glucose biosensors.
authors.affiliation: Department of Biosciences and Bioengineering, IIT Bombay, Powai, Mumbai, India.
authors.forename: Ayesha
authors.initials: A
authors.lastname: Chaudhary
authors.forename: Michael J
authors.initials: MJ
authors.lastname: McShane
authors.forename: Rohit
authors.initials: R
authors.lastname: Srivastava
mesh_terms: D000464:Alginates / Q000737:chemistry* / Q000633:toxicity; D000818:Animals; D001667:Binding, Competitive; D015374:Biosensing Techniques / Q000379:methods*; D002460:Cell Line; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D005456:Fluorescent Dyes / Q000737:chemistry; D005947:Glucose / Q000032:analysis*; D005949:Glucose Oxidase / Q000378:metabolism; D020723:Glucuronic Acid / Q000737:chemistry / Q000633:toxicity; D006603:Hexuronic Acids / Q000737:chemistry / Q000633:toxicity; D051379:Mice; D008863:Microspheres; D049329:Nanostructures / Q000737:chemistry; D012235:Rhodamines / Q000737:chemistry
chemical_list: D000464:Alginates; D005456:Fluorescent Dyes; D006603:Hexuronic Acids; D012235:Rhodamines; C009434:tetramethylrhodamine isothiocyanate; D020723:Glucuronic Acid; D005949:Glucose Oxidase; D005947:Glucose