Rapid Determination of Endogenous 20-Hydroxyecdysone in Plants on MALDI-TOF/TOF Mass Spectrometry via Chemical Labeling Based on Boronate Affinity

20-Hydroxyecdysone(20E)derived from plants has a wide range of physiological and pharmacological ef ects on animals and humans,and rapid and sensitive methods for screening of the endogenous 20E in plants are thus required.Herein,a matrixassisted laser desorption/ionization time-of-f ight tandem mass spectrometry(MALDI-TOF/TOF MS)method is described for rapid and sensitive determination of endogenous 20E in plants.It is based on the use of the(3-(acridin-9-ylamino)phenyl)boronic acid(AYPBA)as the mass tag to assist the MS and tandem MS(MS^(n))analysis of 20E on MALDI-TOF/TOF MS.Good linearity was obtained with a determination coef cient(R^(2))larger than 0.99 in the range of 0.025–2.5μΜ.The limit of detection(LOD)was 2.4 fmol.Acceptable precision and accuracy were gained by intra-and inter-day analysis with relative standard deviations less than 19.5%and relative recoveries ranging from 85.7 to 105.2%.In addition,the AYPBA labeled 20E produced abundant characteristic fragment ions under the high energy collision-induced dissociation,which facilitated the identif cation of 20E by MS^(2)analysis on MALDI-TOF/TOF MS.Using the method,we enabled the identif cation and quantif cation of endogenous 20E in four herbs including Cyanotis arachoidea,Achyranthes bidentata,Spinacia oleracea and Chenopodium quinoa willd.,demonstrating the feasibility of the proposed method for screening of the endogenous 20E in plants.

A boronate affinity restricted-access material with external hydrophilic bottlebrush polymers for pretreatment of cis-diols in biological matrices

Restricted-access materials （RAMs） have found their broad application in sample pretreatment of bioanalysis. Boronate affinity （BA） adsorption is a very efficient and facile method for isolation and enrichment of cis-diol containing biomolecules which are a large important group compounds in biosystems. However, preparation of BA-RAMs are rarely reported to date. In this study, a novel BA-RAM with external surface comprised of hydrophilic bottlebrush polymers was prepared exploiting the excellent capability of the bottlebrush polymers for protein exclusion. A diblock copolymer poly（3- acrylamidophenylboronic acid）-block-poly（2-hydroxyethyl methacrylate） （PAAPBA-b-PHEMA） was first grafted from the silica surface via surface-initiated reversible addition-fragmentation chain transfer polymerization （SI-RAFT）, and poly（N-isopropylacrylamide） （PNIPAAm） was then grafted from the PHEMA via surface-initiated atom transfer radical polymerization （SI-ATRP） to yield the BA-RAM. The BA- RAM exhibits high selectivity to cis-diol containing small molecules and has good capability to exclude proteins. Its practical application in bioanalysis was tested by pretreatment of serum sample for analysis of catecholamines with high recoveries and good precision. The preparation strategy for the BA-RAM is very versatile and is easy to be expanded to other modes of RAMs.