Characterization of Lactate Sensors Based on Lactate Oxidase and Palladium Benzoporphyrin Immobilized in Hydrogels

Abstract

An optical biosensor for lactate detection is described. By encapsulating enzyme-phosphor sensing molecules within permeable hydrogel materials, lactate-sensitive emission lifetimes were achieved. The relative amount of monomer was varied to compare three homo- and co-polymer materials: poly(2-hydroxyethyl methacrylate) (pHEMA) and two copolymers of pHEMA and poly(acrylamide) (pAam). Diffusion analysis demonstrated the ability to control lactate transport by varying the hydrogel composition, while having a minimal effect on oxygen diffusion. Sensors displayed the desired dose-variable response to lactate challenges, highlighting the tunable, diffusion-controlled nature of the sensing platform. Short-term repeated exposure tests revealed enhanced stability for sensors comprising hydrogels with acrylamide additives; after an initial “break-in” period, signal retention was 100% for 15 repeated cycles. Finally, because this study describes the modification of a previously developed glucose sensor for lactate analysis, it demonstrates the potential for mix-and-match enzyme-phosphor-hydrogel sensing for use in future multi-analyte sensors.

Composite Hydrogels with Engineered Microdomains for Optical Glucose Sensing at Low Oxygen Conditions

“…The oxygen concentration was regulated by a vacuum degassing chamber (9000–1118, Systec) and vacuum pump (9000-1472, Systec). All optical measurements were recorded using a custom-built time domain phosphorescence lifetime measurement instrument with a 530 nm excitation source described elsewhere [22,23]. The combination of the AnA hydrogel (bioresponsive material) with the lifetime measurement unit (detector) will be referred to as the “sensing system”.…”

“…Insensitivity to electromagnetic interference (EMI) and low/zero-power operation with facile recharging are additional desirable properties [21]. To meet these requirements in an approach that offers the additional advantage of avoiding the use of implanted electronics, our group has recently developed bioresponsive materials that respond to lactate and glucose by covalently immobilizing oxidoreductase enzymes and an oxygen-sensitive metalloporphyrin dye within biocompatible hydrogel matrices [22,23]. These unique materials transduce chemical concentration into optical information (phosphorescence intensity or lifetime).…”

A review of gradient stiffness hydrogels used in tissue engineering and regenerative medicine

“…Cross‐linking enzymes encapsulated in hydrogels has shown to enhance catalytic stability . Studies showed that hydrogel composition, degradation and swelling properties could affect the delivery rate of analyte . By switching the enzyme and adjusting the hydrogel properties, sensitive and stable sensors could be developed .…”

“…112 Studies showed that hydrogel composition, degradation and swelling properties could affect the delivery rate of analyte. [113][114][115] By switching the enzyme and adjusting the hydrogel properties, sensitive and stable sensors could be developed. 115 Gradient stiffness hydrogels process varying composition and structure density on one single hydrogel.…”

“…[113][114][115] By switching the enzyme and adjusting the hydrogel properties, sensitive and stable sensors could be developed. 115 Gradient stiffness hydrogels process varying composition and structure density on one single hydrogel. The same approach may, in principle, be used to extend the range of analytes and utilized in multicomponent sensors.…”