title: Gel encapsulation of glucose nanosensors for prolonged in vivo lifetime.
abstract: BACKGROUND
  Fluorescent glucose-sensitive nanosensors have previously been used in vivo to track glucose concentration changes in interstitial fluid. However, this technology was limited because of loss of fluorescence intensity due to particle diffusion from the injection site. In this study, we encapsulated the nanosensors into injectable gels        to mitigate nanosensor migration in vivo.
  
  
  METHODS
  Glucose-sensitive nanosensors were encapsulated in two different commercially available gelling agents: gel 1 and gel 2. Multiple formulations of each gel were assessed in vitro for their nanosensor encapsulation efficiency, permeability to glucose, and nanosensor retention over time. The optimal formulation for each gel, as determined from the in vitro assessment, was then tested in mice, and the lifetime of the encapsulated nanosensors was compared with controls of nanosensors without gel.
  
  
  RESULTS
  Five gel formulations had encapsulation efficiencies of the nanosensors greater than 90%. Additionally, they retained up to 20% and 40% of the nanosensors over 24 h for gel 1 and gel 2, respectively. In vivo, both gels prevented diffusion of glucose nanosensors at least three times greater than the controls.
  
  
  CONCLUSIONS
  Encapsulating glucose nanosensors in two injectable gels prolonged nanosensor lifetime in vivo; however, the lifetime must still be increased further to be applicable for diabetes monitoring.
authors: Department of Bioengineering, Northeastern University, Boston, Massachusetts 02115, USA.
authors: Mary K
authors: MK
authors: Balaconis
authors: Heather A
authors: HA
authors: Clark
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000295:instrumentation* / Q000379:methods; D001786:Blood Glucose / Q000032:analysis*; D005782:Gels; D051379:Mice; D036103:Nanotechnology / Q000295:instrumentation* / Q000379:methods
chemical_list: D001786:Blood Glucose; D005782:Gels