L-tryptophan is the most widely distributed indole derivative in nature and one of the essential amino acids, which can be used as a synthetic precursor of serotonin, melatonin and serotonin. L-Tryptophan is also a limiting amino acid in animal nutrition. Therefore, rapid and accurate quantification of L-tryptophan is essential. However, L-tryptophan is easily decomposed in an acidic environment, which causes great inconvenience to the quantitative determination of L-tryptophan in feed. The development of a biosensor that can be used for the rapid detection of L-tryptophan in feed or animal body fluids in the field will provide a convenient means for the determination of L-tryptophan in the field of animal nutrition, and can also be applied to food, medicine and other fields.
In order to solve the above problems, the team of academician Yin Yulong from the Institute of Agroecology of the Chinese Academy of Sciences used the previously screened L-tryptophan peptide aptamer and synthesized a colloidal gold solution with a surface modified peptide aptamer by sodium borohydride reduction methodThe synthesis of nanomaterials and their sensitivity to L-tryptophan were verified spectroscopically using TEM, FT-IR, XPS, and Zeta potential and particle size analyzers. The results showed that when L-tryptophan was added to the colloidal gold solution in proportion, the color of the solution changed from burgundy to dark blue after 10 s of ** mixing, and the maximum absorption wavelength of the solution migrated from 535 nm to 600-620 nm. After optimizing the process conditions, the developed biosensor showed a good linear relationship between 1-50 m and 50-1000 m for the gradient concentration of L-tryptophanThe developed biosensor can exclude the interference of ascorbic acid and uric acid in serum, and is not significantly interfered with by 16 other common amino acidsDuring the 7-day stability test, there was no significant change in the color of the solution per day, and the absorbance RSD value at 535 nm was 482%；The developed biosensor has a ** rate of 99 in pig serum testing2%-100.2%。In summary, this study designed a fast, simple, sensitive, and highly selective colorimetric L-tryptophan biosensor based on peptide aptamers and gold nanoparticles, which has the characteristics of simple structure and operation, high sensitivity, and good selectivity, and can be used for the rapid detection of L-tryptophan in porcine serum and other samples.
The above research results were published in Microchemical Journal, a top journal, with the title of peptide aptamer-based colorimetric sensor for the detection of L-tryptophan in porcine serum. This research was supported by the National Key R&D Program of China (2021YFD2000800), the National Natural Science Program of China (31527803), the China Postdoctoral Science Program (2022T150075, 2022M720541), and the Special Project for the Construction of Modern Agricultural Industrial Technology System (CARS-35).
Fig.1 Transmission electron microscopy images of PEP-AU before (A) and after (B) addition of L-tryptophan (1 mM), ZETA potential curves of bare AU NPS, PEP-AU and Pep-Au supplemented with L-tryptophan (C), and FTIR spectra of PEP-AU (D).
Fig.2 Mechanism diagram of aptamer-based colorimetric biosensor for detection of L-tryptophan.
Figure 3 (a) Addition of different concentrations of L-tryptophan (top) followed by 1Solution image of PEP-AU after 0 M KCl (lower). (b) Correlation between L-tryptophan concentration and absorbance at 618 nm wavelength. (c) After adding different concentrations of L-TRP solution, add 10 M kCl, UV-Vis absorption spectrum of PEP-AU.