研究目的
To develop a sensitive, selective, and label-free detection method for L-phenylalanine (L-Phe) using a liquid crystal-based sensing platform based on the inhibition of alkaline phosphatase (ALP) by L-Phe.
研究成果
The liquid crystal-based sensing platform successfully enables sensitive and selective detection of L-Phe with a detection limit of 1 pg/mL, leveraging the inhibition of ALP. It outperforms existing methods in sensitivity and selectivity, demonstrating practical applicability in urine samples for clinical diagnostics of phenylketonuria. This approach paves the way for developing robust, label-free probes for L-Phe detection.
研究不足
The sensitivity of the sensor may be affected by pH and ionic strength variations, requiring optimization for different conditions. The method relies on the specific inhibition of ALP by L-Phe, which might be influenced by other inhibitors or environmental factors. The stability of the SMP layer and enzymatic reactions could be time-dependent, potentially limiting real-time applications.
1：Experimental Design and Method Selection:
The study designed a liquid crystal (LC) sensing platform using sodium monododecyl phosphate (SMP) to decorate the aqueous/LC interface, inducing a homeotropic orientation of LCs that appears dark under polarized light. Alkaline phosphatase (ALP) is used to hydrolyze SMP, changing the orientation to planar and the appearance to bright. L-Phe inhibits ALP, preventing this change and maintaining the dark appearance. This optical response is used for detection.
2：Sample Selection and Data Sources:
Samples include ALP from bovine intestinal mucosa, various amino acids (e.g., L-Phe, L-Met, L-Tyr), and human urine samples from healthy volunteers. Solutions were prepared in Tris-HCl buffered solution (TBS, pH 8.0).
3：0).
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Key materials include SMP, ALP, amino acids, nematic LC 4-cyano-4′-pentylbiphenyl (5CB), octyltrichlorosilane (OTS), copper specimen grids, and buffers. Equipment includes a polarized light microscope (XPF-800C, Tianxing), digital camera (TK-9301EC, JVC), pH meter (PHS-3C, Jingmikexue), and isothermal titration calorimetry apparatus (Microcal VP-ITC).
4：Experimental Procedures and Operational Workflow:
OTS-coated glass slides were prepared. Optical cells were made by distributing 5CB onto copper grids on OTS slides. Aqueous solutions (e.g., SMP, ALP, L-Phe mixtures) were introduced to the interface. Optical images were captured over time, and bright area coverage ratios were calculated. ITC measurements were performed to quantify inhibition.
5：Data Analysis Methods:
Optical images were analyzed using Photoshop to calculate bright area coverage ratios. ITC data were used to determine dissociation constants (KD). Statistical analysis involved repeating experiments at least three times.
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