[en] A new general approach called in situ digestion-assisted multi-template imprinting is proposed for preparation of phospho-specific molecularly imprinted nanoparticles. Through the novel templating strategy and controllable imprinting process, imprinted nanoparticles specific to the intact phosphoprotein and its phosphopeptides were synthesized. The prepared imprinted nanoparticles exhibited excellent specificity (cross reactivity < 10%), high affinity (10⁻⁶ M), high efficiency (47.5%), and good generality (both intact phosphoprotein and phosphopeptides). We also realized the fine tuning of the recognition at peptide level of the imprinted nanoparticles by adjusting the imprinting time. Based on the selective enrichment of the imprinted nanoparticles, the MS identification of both the intact phosphoprotein (Tau) and phosphopeptides (angiotensin II and peptides of Tau) in real complex samples could be achieved. Therefore, we believe that the in situ digestion-assisted multi-template imprinting strategy holds promising future in both phosphorylation analysis and proteomics applications. Graphical abstract

[en] A highly oriented crystalline metal-organic framework (MOF) nanofilm array was prepared and used for surface-assisted laser desorption ionization mass spectrometry (SALDI-MS) for determination of small molecules. The MOF nanofilm was characterized using scanning/transmission electron microscopy, X-ray diffraction, and ultraviolet-visible spectroscopy. Different small molecules (anthracene, n-eicosanoic acid, Rhodamine B) were successfully determined by this MOF nanofilm array with limits of detection (LOD) between 0.1–5 ng·mL⁻¹ and limits of quantification (LOQ) between 1 and 10 ng·mL⁻¹. Compared to previously reported MOF-based SALDI-MS, this array exhibits better reproducibility (3.3–5.2%) and recovery (89–105%). The intensity of the MS peak remains the same after 25 repeated cycles. This indicates good repeatability. This MOF nanofilm-based SALDI-MS array can be used for determination of fatty acid and Rhodamine B in real samples with good recovery (83–106%).

[en] Highlights: • This review focuses on boronate affinity material for sample preparation. • The review covers various types of advanced boronate affinity materials. • The review surveys publications on practical applications of boronate affinity materials for sample preparation. • Critical reviews of synthetic strategies and practical use of boronate affinity materials were provided. -- Abstract: Boronate affinity materials, as widely used sorbents for the enrichment of cis-diol-containing molecules, have been rapidly developed and increasingly utilized for various applications in recent years. cis-Diol-containing molecules, including saccharides, nucleosides, catecholamines, glycans and glycoproteins/glycopeptides, are major targets in the frontiers of many research areas, such as environmental analysis, the food industry and bioanalysis. As the analysis of these molecules usually suffers from the low abundance of targets and the high abundance of interference, selective enrichment is a fundamental step of sample preparation before analysis. In this review, we survey recent achievements of boronate affinity materials and their applications in sample preparation. We mainly focus on the fundamental considerations of materials as well as important applications in the past 3 years. Particularly, the effects of the substrate structure on the performance of boronate affinity materials, such as binding capacity, affinity, selectivity and working pH, will be discussed. Furthermore, the applications in sample preparation will also be introduced, with a main emphasis on what merits can be provided by boronate affinity materials to overcome the challenges in sample preparation.

[en] Highlights: • Boronate affinity metal-organic frameworks are used for SALDI-MS for the first time. • An in-situ enrichment and MS detection method for analysis of cis-diol molecules. • Three cis-diol molecules were extracted and analyzed with BA-MOFs. • Efficient analysis of cis-diol molecules for human urine, serum and tea drinks. -- Abstract: Development of novel matrix for surface-assisted laser desorption/ionization mass spectrometry (SALDI-MS) is a hot-spot in research frontiers. Herein, we established novel SALDI-MS approach for the analysis of cis-diol small molecules by using boronate affinity metal-organic frameworks (BA-MOFs) as the sorbent for extraction and later as matrix for SALDI. In the meantime, the prepared BA-MOFs exhibited several significant merits, such as excellent selectivity, tolerance to interference and fast binding equilibria. By integrating the advantages of MOFs and the molecular recognition of boronate affinity, a novel platform for simultaneous enrichment and MS detection of cis-diol small molecules was proposed for the first time. There are only two steps in the operation procedure, which greatly simplified the whole experimental workflow. Efficient analysis of cis-diol small molecules in real samples were also well demonstrated. This proposed novel protocol not only gave new insights into the application of functionalized MOFs, but also promoted the development of SALDI- MS.