An enzyme Biosensor Based on Organic Transistors for Recognizing α-Amino Acid Enantiomers

Abstract

The chiral recognition of α-amino acids has attracted considerable interest because different enantiomeric amino acids show differences in their biological behavior and pharmacological activity. An organic electrochemical transistor (OECT)-based biosensor modified with L-amino acid oxidases (L-AAODX) was fabricated and successfully used as a biosensor for enantioselectively discriminating α-amino acids, such as D/L-tryptophan (D/L-Trp), D/L-tyrosine (D/L-Tyr) and D/L-phenylalanine (L-Phe) with high performance because L-AAODX selectively catalyzed the oxidation of L-Trp, L-Tyr, and L-Phe along with the amplification of OECT. The biosensor showed a sensitivity of 19.67 μA/μM with a LOD of 10 nM (S/N > 3) over the range of 10 nM to 30 μM for L-Trp, 16.71 μA/μM with a LOD of 2 nM (S/N >3) over the range of 2 nM to 30 μM for L-Tyr and 15.51 μA/μM with a LOD of 10 nM (S/N > 3) over the range of 30 nM to 30 μM for L-Phe. Furthermore, the biosensor can both be used for the chiral recognition of Trp, Tyr and Phe, and distinguish L-amino acids from its interferences (e.g., Glu, UA, L-Asp, L-Lys and L-Glu) and common metal ions (K+, Na+ and Fe3+).

Porous Semiconducting Polymers Enable High‐Performance Electrochemical Transistors

“…Pg2T‐T was synthesized according to ref. [ 23 ] (Mw = 98 kDa, Mn = 38 kDa, PD = 2.55; DMF at 80 °C). All three materials were dissolved in CHCl 3 to a concentration of 6 mg mL −1 .…”

“…This characteristic is promising for detecting small signals in bio‐system applications as shown recently for highly sensitive chemical and biological sensors, brain activity monitoring, and cell function modulation. [ 2,4,5,10–29 ] Indeed the limits of detection for biosensors up to attomolar levels can be achieved by utilizing capacitive coupling between the large 3D capacitance of the channel material and the sensing gate. [ 28 ]…”

“…This characteristic is promising for detecting small signals in bio-system applications as shown recently for highly sensitive chemical and biological sensors, brain activity monitoring, and cell function modulation. [2,4,5,[10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29] Indeed the limits of detection for biosensors up to attomolar levels can be achieved by utilizing capacitive coupling between the large 3D capacitance of the channel material and the sensing gate. [28] Because OECT operation must rely on both ionic and charge (electron/hole) transport, balancing/optimizing both processes has proven challenging.…”

Dual Signals Electrochemical Biosensor for Point‐of‐Care Testing of Amino Acids Enantiomers

“…Only L‐AA is an essential amino acid that constitutes the protein of the human body [16–18]. Taking tyrosine (Tyr) as an example, L‐Tyr participates in physiological activities of the human body and is accepted as an essential precursor for the synthesis of thyroxine [18–20], epinephrine [21–23], dopamine and other substances [24–26]. The lack of L‐Tyr will lead to the decline of thyroid function and the generation of various diseases [21, 27–28].…”