The application of label-free imaging technologies in transdermal research for deeper mechanism revealing

The penetration behavior of topical substances in the skin not only relates to the transdermal delivery efficiency but also involves the safety and therapeutic effect of topical products,such as sunscreen and hair growth products.Researchers have tried to illustrate the transdermal process with diversified theories and technologies.Directly observing the distribution of topical substances on skin by characteristic imaging is the most convincing approach.Unfortunately,fluorescence labeling imaging,which is commonly used in biochemical research,is limited for transdermal research for most topical substances with a molecular mass less than 500 Da.Label-free imaging technologies possess the advantages of not requiring any macromolecular dyes,no tissue destruction and an extensive substance detection capability,which has enabled rapid development of such technologies in recent years and their introduction to biological tissue analysis,such as skin samples.Through the specific identification of topical substances and endogenous tissue components,label-free imaging technologies can provide abundant tissue distribution information,enrich theoretical and practical guidance for transdermal drug delivery systems.In this review,we expound the mechanisms and applications of the most popular label-free imaging technologies in transdermal research at present,compare their advantages and disadvantages,and forecast development prospects.

Phytosulfokine-α Promotes Root Growth by Repressing Expression of Pectin Methylesterase Inhibitor (PMEI) Genes in Medicago truncatula

Phytosulfokine-α(PSK-α),a sulfated pentapeptide with the sequence YIYTQ,is encoded by a small precursor gene family in Arabidopsis.PSK-αregulates multiple growth and developmental processes as a novel peptide hormone.Despite its importance,functions of PSK-αin M.truncatula growth remains unknown.In this study,we identified five genes to encode PSK-αprecursors in M.truncatula.All of these precursors possess conserved PSK-αsignature motif.Expression pattern analysis of these MtPSK genes revealed that each gene was expressed in a tissue-specific or ubiquitous pattern and three of them were remarkably expressed in root.Treatment of M.truncatula seedlings with synthetic PSK-αpeptide significantly promoted root elongation.In addition,expression analysis of downstream genes by RNA-seq and qRT-PCR assays suggested that PSK-αsignaling might regulate cell wall structure via PMEI-PME module to promote root cell growth.Taken together,our results shed light on the mechanism by which PSK-αpromotes root growth in M.truncatula,providing a new resource for improvement of root growth in agriculture.

Enzymatic cascade systems for D-amino acid synthesis:progress and perspectives

D-amino acids,different from the ubiquitous L-amino acids,are recognized as the“unnatural”amino acids.The applications of D-amino acids have drawn increasing interest from researchers in recent years,and D-amino acids are widely used in various industries,including for food products,pharmaceuticals,and agricultural chemicals.Inspired by the prevalent appli-cations,many synthetic methods for D-amino acids have been developed,which are mainly divided into chemical synthetic methods and biosynthetic methods.Chemical synthesis of D-amino acids has a variety of disadvantages such as multiple reaction steps,low yields,low reaction rates,and difficulties in product extraction.Thus,biosynthetic methods utilizing enzymes are attracting increasing attention because they are more energy-saving and environmentally friendly compared to traditional chemical synthesis.Among all enzymatic methods,multi-enzymatic cascade catalytic methods have significant advantages,such as lower costs,no need for intermediate separation,and higher catalytic efficiency,which is ascribed to the spatial proximity of biocatalysts.In this review,advances in multi-enzyme cascade catalytic systems as well as chemo-enzymatic approaches to synthesize D-amino acids are discussed.