Fabrication of an Implantable Fine Needle-Type Glucose Sensor Using γ-Polyglutamic Acid

Abstract

Implantable fine needle-type glucose sensors with an outer diameter of less that 0.2 mm were fabricated using a low-cost and non-animal origin polyamide, gamma-polyglutamic acid (PGA) as a glucose oxidase (GOx) immobilizing material. Two types of PGA, gamma-polyglutamic acid (PGAH) and gamma-polyglutamic acid sodium salt (PGANa), were employed to prepare GOx immobilized film by the covalent attachment of GOx using water-soluble carbodiimide (EDC). Nafion/cellulose acetate composite film and polyurethane/polydimethylsiloxane composite film were employed as a permselective inner film and a biocompatible outer film, respectively. The procedure of enzyme-immobilized film fabrication affected the stability of the sensor; that is, GOx immobilized film prepared by pouring a mixture solution of GOx and EDC on a PGA precoated surface showed higher sensor stability than that prepared by pouring a mixture solution of GOx, PGA and EDC. Although, obvious differences in the sensor properties were not observed between the use of PGANa and PGAH, the electrode prepared with PGAH had a lower swelling degree. The glucose sensors prepared with both PGANa and PGAH were practically not affected by the existence of electroactive compounds, such as uric acid, and provided long-term stability for approximately 5 weeks. These sensors also showed good performance in horse serum.

Highly Selective Needle-Type Glucose Sensors Prepared by the Immobilization of Glucose Oxidase on γ-Polyglutamic Acid Film

“…29 We previously reported that PGA can be employed as an enzyme immobilizing material for the preparation of a fine needle-type glucose sensor. 28 The sensor properties of the obtained GOx-immobilized electrode were comparable to that of a sensor prepared by the most commonly used method, cross-linking of Fine needle-type glucose sensors with an outer diameter of less that 0.2 mm were fabricated using a low-cost biodegradable γ-polyglutamic acid (PGA) not only as a glucose oxidase (GOx) immobilizing material, but also as a permselective inner membrane. PGA film was prepared on a cellulose acetate-coated Pt-Ir wire electrode, and GOx was covalently immobilized on its surface using water-soluble carbodiimide.…”

“…[16][17][18][19] Moreover, perfluorinated-sulfonated ion-exchange polymer "Nafion ® " is another popularly used material in the fabrication of biosensors, since it is known to be effective for eliminating the influence of electroactive compounds on the sensor response by an electrostatic interaction. [19][20][21][22][23][24][25][26][27][28] Recently, a low-cost non-animal origin biodegradable polyamino acid, γ-polyglutamic acid (PGA), has received attention for clinical applications due to its good biocompatibility. 29 We previously reported that PGA can be employed as an enzyme immobilizing material for the preparation of a fine needle-type glucose sensor.…”

Development of an Electrochemical Cholesterol Sensor System for Food Analysis

“…Due to this difficulty, highly selective sensors are mostly fabricated using biologically acquired ligands, such as enzymes and antibodies. [1][2][3][4][5][6][7] However, these ligands are usually expensive and prone to lose their activities for prolonged use. It is therefore desired to make use of artificial receptors possible, especially in low-cost sensing applications as well as in harsh chemical and/or physical environments.…”

Fabrication of Amperometric Glucose Sensor Using Glucose Oxidase-Cellulose Nanofiber Aqueous Solution

“…Immobilization of the enzyme is one of the most critical processes for the fabrication of an enzyme sensor, since it will highly influence properties of the obtained sensor. Various procedure have been proposed for the preparation of a glucose sensor, such as covalent attachment, [1][2][3] cross-linking, 1,[4][5][6][7][8][9][10][11][12][13][14] hydrogel entrapment, 15,17 polymer film entrapment, 6,[17][18][19][20] and the combination of two or more methods. [21][22][23][24] On the other hand, the concept of green chemistry has infiltrated various fields of the manufacturing industry.…”