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Construction of liquid crystal-based sensing platform for sensitive and selective detection of L-phenylalanine based on alkaline phosphatase
摘要： The detection of L-phenylalanine (L-Phe) has become one of most pressing issues concerning diagnosis and treatment of phenylketonuria in neonates, yet a simple and robust methodology has yet to be developed. Here the application of novel liquid crystals (LCs) sensing platform for sensitive, selective, and label-free detection of L-Phe was reported at the first time. We devised a strategy to fabricate the sodium monododecyl phosphate (SMP) decorated LC sensing platform with the appearance of dark. Then, a dark to bright (D-B) optical images alteration of LCs was observed after transferring alkaline phosphatase (ALP) to the interface, owing to cleavage of SMP induced by ALP. LCs remained dark images after the SMP-decorated interface in contact with the pre-incubated ALP and L-Phe. Such optical appearance resulted from the inhibition of ALP by L-Phe, which was further verified by the isothermal titration calorimetry (ITC). The strategy was applied to sensing L-Phe, which have been proven to allow for sensitively and selectively differentiation of L-Phe from interfering compounds with similar aromatic groups, as well as seven other essential amino acids. More importantly, the detection limit of L-Phe reached 1 pg/mL in urine samples, further demonstrated its value in the practical applications. Results obtained in this study clearly demonstrated the superiority of LCs towards the L-Phe detection, which can pave a way for the development of high performance and robust probes for L-Phe detection in clinical applications.
关键词： Sensing platform,Alkaline phosphatase,Surfactant,Liquid crystal,Inhibition,L-phenylalanine
更新于2025-09-23 15:23:52
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Mutated Human P-Selectin Glycoprotein Ligand-1 and Viral Protein-1 of Enterovirus 71 Interactions on Au Nanoplasmonic Substrate for Specific Recognition by Surface-Enhanced Raman Spectroscopy
摘要： Protein tyrosine sulfation is a common post-translational modification that stimulates intercellular or extracellular protein-protein interactions and is responsible for various important biological processes, including coagulation, inflammation, and virus infections. Recently, human P-selectin glycoprotein ligand-1 (PSGL-1) has been shown to serve as a functional receptor for enterovirus 71 (EV71). It has been proposed that the capsid viral protein VP1 of EV71 is directly involved in this specific interaction with sulfated or mutated PSGL-1. Surface-enhanced Raman spectroscopy (SERS) is used to distinguish PSGL-1 and VP1 interactions on an Au nanoporous substrate and identify specific VP1 interaction positions of tyrosine residue sites (46, 48, and 51). The three tyrosine sites in PSGL-1 were replaced by phenylalanine (F), as determined using SERS. A strong phenylalanine SERS signal was obtained in three regions of the mutated protein on the nanoporous substrate. The mutated protein positions at (51F) and (48F, 51F) produced a strong SERS peak at 1599–1666 cm?1, which could be related to a binding with the mutated protein and anti-sulfotyrosine interactions on the nanoporous substrate. A strong SERS effect of the mutated protein and VP1 interactions appeared at (48F), (51F), and (46F, 48F). In these positions, there was less interaction with VP1, as indicated by a strong phenylalanine signal from the mutated protein.
关键词： viral protein 1,P-selectin glycoprotein ligand-1,surface-enhanced Raman spectroscopy,nanoporous,phenylalanine
更新于2025-09-23 15:21:01
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Nanostructured paper-based platform for phenylalanine neonatal screening by LED-induced fluorescence
摘要： In this work, a novel paper-based analytical device (PAD) coupled to LED-induced fluorescence (LIF) detection (fPAD) for the rapid, selective, and sensitive quantification of phenylalanine (Phe) in neonatal samples was developed. Enzymes Phenylalanine dehydrogenase (PheDH) and diaphorase were immobilized on a paper microzone previously modified with zinc oxide nanoparticles (ZnONPs) coated with chitosan (CH-ZnONPs). Phe was extracted from the blood spots collected samples on filter paper and was mixed with nicotinamide adenine dinucleotide (NAD+) and resazurin. Then the mixture was deposited on the reaction microzone of the fPAD where PheDH converts the Phe and NAD+ to phenylpyruvate and NADH, respectively. Finally, NADH was oxidized by diaphorase with the consequent reduction from resazurin to resorufin. This latter was detected by LIF using an excitation wavelength of 535 nm and an emission of 580 nm in a synchronized video microscope. We compare the responses of the PADs with and without nanomaterials to demonstrate the improved analytical performance of the developed devices. For this, the PADs were modified with the same concentration of horseradish peroxidase (HRP). The fluorescent signal obtained from the PADs with nanomaterials was higher than that of the unmodified PADs. Our method exhibited within- and between-assay variation coefficients below 5.23% and 6.67%, respectively. The detection limit obtained by the developed device was 0.125 μM. The proposed fPAD allowed the simple, rapid, low-cost, and sensitive detection of Phe in neonatal blood samples.
关键词： zinc oxide nanoparticles,Phenylalanine,Paper-based analytical device,Enzymatic method,Fluorometric detection
更新于2025-09-23 15:19:57
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Growth Promotion of Targeted Crystal Face by Nano-Processing via Laser Ablation
摘要： Control of crystal shape is an indispensable step for various applications of crystalline products. However, obtaining the desired crystal shape by conventionally tuning environmental conditions (temperature, additives, etc.) cannot always be reached. Recently, we have developed an innovative approach for spatiotemporal control of crystal growth of proteins and amino acids by locally modifying crystal structure (e.g., formation of screw dislocations) via femtosecond (fs) laser ablation. In this work, to clarify the appropriate laser condition for controlling the shape of single crystals with minimized damage, we first systematically investigated the dependence of pulse duration on laser ablation and crystal growth of L-phenylalanine (L-Phe). By using a laser system with tunable pulse durations from fs to nanosecond (ns), we found fs laser ablation can offer nanometer-sized, sharp etching of which diameter was smaller than the diffraction limit. By utilizing such nano-processing via fs laser ablation for promoting the growth of a targeted crystal face, we successfully demonstrated the preparation of a bulky crystal of L-Phe, which are difficult to be obtained by conventional crystallization methods.
关键词： L-phenylalanine,nano-processing,single crystal growth,crystal shape control,femtosecond laser ablation
更新于2025-09-11 14:15:04
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In situ reflection imaging and microspectroscopic study on three-dimensional crystal growth of L-phenylalanine under laser trapping
摘要： We investigate growth behavior of an L-phenylalanine crystal formed by laser trapping with the use of reflection imaging and microspectroscopy. Optical reflection micrographs show colored images of the crystal due to constructive interference of incident white light. The color distribution on the crystal is dynamically changed under laser trapping, which is in addition to enlargement of the crystal plane area. The temporal change in the crystal thickness is examined by measuring reflection spectra of the crystal. We discuss the three-dimensional crystal growth under laser trapping by comprehensively considering the changes in crystal thickness and crystal plane area.
关键词： reflection imaging,laser trapping,L-phenylalanine,crystal growth,microspectroscopy
更新于2025-09-11 14:15:04
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Changes in enzyme activities and amino acids and their relations with phenolic compounds contents in okra treated by LED lights of different colors
摘要： Light-emitting diodes (LEDs) of different wavelengths or colors (i.e., white, red, blue, and green) were used to treat postharvest okra, which is a rich source of phenolic compounds. Relationships between changes in the activities of key enzymes involving in the formation of phenolics (i.e., 3-deoxy-D-arabino-heptulosonate 7-phosphate synthase, chorismate mutase, anthranilate synthase, and phenylalanine ammonia lyase) and their contents upon different LED light treatments were for the first time investigated and are fully discussed. The contents of three intermediate amino acids (i.e., phenylalanine, tyrosine, and tryptophan) that formed during light treatments were also measured to confirm the enzyme activities data. White and blue light treatments increased the content of phenolics in the treated okra, while red and green lights increased the formation of other compounds. These results could be well explained by the changing levels of the measured enzyme activities and amino acids contents.
关键词： Non-thermal processing,Phenylalanine ammonia lyase,Fruits and vegetables,Phenylpropanoid pathway,Shikimate pathway,LED
更新于2025-09-11 14:15:04
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Induction of postharvest resistance in melon using pulsed light as abiotic stressor
摘要： The aim of this study was use the pulsed light (PL) as tool to booster the postharvest resistance in melons. Cantaloupe melons at mature stage were submitted to the treatments as follows: control, pulsed light (PL; 9 J cm?2), 1-methylcyclopropene (1-MCP; 600 nL L-1) and 1-MCP + PL (600 nL L-1 + 9 J cm?2). Postharvest resistance measurements according survival analysis developed at 4 °C, included: ethylene production, 1-aminocyclopropane-L-carboxylic acid (ACC) oxidase activity, ACC synthase activity, firmness, pH, soluble solids, titratable acidity, SS/AT ratio, soluble sugars, vitamin C, total polyphenols, phenylalanine ammonia lyase (PAL) activity, colour epicarp, free polyamines (putrescine-Put, spermine-Spe and spermidine-Spd) and total polyamines (TPo). Combined effect of the PL+1-MCP promoted an additional of 12 days in the shelf life of melons. PL limited the ethylene biosynthesis leading to an immediate upregulation of polyamines (Put + Spe + Spd), hence, associated with high amounts of TPo (56%). PL treatment promoted an increase of PAL activity (67%) that synthesized high content of phenolic compounds (55%). The results suggest that PL with a fluence of 9 J cm?2 stimulate the postharvest defense mechanisms in melon, due to the ethylene production limitation, which was influenced by the increased polyamines, maintaining the quality attributes.
关键词： Ethylene,Putrescine,Abiotic stress,Polyamines,Phenylalanine ammonia lyase
更新于2025-09-10 09:29:36
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Enhanced Antioxidant Capacity of Fresh Blueberries by Pulsed Light Treatment
摘要： As a novel technology for food safety risk mitigation, pulsed light (PL) has been shown effective in surface decontamination of fresh blueberries in literature. However, little is known about the effects of PL on the antioxidant capacity and quality characteristics of fresh blueberries. Fresh blueberries from a local farm were treated with PL for 30, 60, 90 and 120 s. Results show that PL exposure enhanced the antioxidant activity (ORAC) and total phenolic content of fresh blueberries 50 and 48% respectively, relative to the control. Pulsed light also significantly increased the total anthocyanin contents, which may be due to the upregulation of Phenylalanine Ammonium Lyase (PAL) enzymes. There was no significant difference (P ≤ 0.05) in the soluble solids, pH, titratable acidity, firmness, color and mass of the fresh blueberries within 120 s PL exposure. In conclusion, PL illumination enhanced the antioxidant capacity of fresh blueberries while maintaining other quality characteristics.
关键词： phenolics,phenylalanine ammonium lyase,phytochemical,nonthermal,flavonoids,anthocyanins
更新于2025-09-09 09:28:46