Noncovalent Tagging for Identifying Unknown Contaminants of Specific Bioactivity in Environmental Water.

Identifying contaminants of specific bioactivities from complicated environmental matrices remains costly and time-consuming, as it requires us to not only resolve their structures but also determine their bioactivities. Herein, a novel noncovalent tagging method is integrated in mass spectrometry for identifying unknown contaminants that target dopamine (DA) receptors. Via proteolysis of bovine serum albumin, a stereoselective hexapeptide (ACFAVE) is selected for noncovalently tagging the contaminants that possess the stereostructural characteristics of binding to DA receptors. The tagged contaminants can be readily distinguished from the coexisting species for subsequent structural analysis based on the tagging-induced shifts of the mass-to-charge ratios. Thus, both bioactivity evaluation and structure analysis are accomplished via mass spectrometry. By using this method, 1,3-diphenylguanidine (DPG), a widely used additive in rubber and plastics, is successfully identified out of 2495 features detected in the Pearl River water, with its concentration determined as only 9.8 µg L-1. Furthermore, DPG is confirmed as a potential disrupter to the DA receptors via a simulated docking experiment, which has not been reported before. The present noncovalent tagging method provides a cost-effective and time-efficient way of identifying bioactive molecules in complicated matrices. And proteolysis of proteins is promising for developing more taggants with other desired stereoselectivities in the future.

Novel lanthanide nanoparticle frameworks for highly efficient photoluminescence and hypersensitive detection.

Despite the excellent luminescent properties of lanthanide clusters (LnCs), their suprastructures that inherit their characteristic luminescent properties are scarcely reported. Herein, novel and highly luminescent suprastructures are synthesized via a two-step assembly method to incorporate LnCs in covalent organic frameworks (COFs). COFs are pre-synthesized and decorated with rigid anchoring groups on their nanochannel walls, which provide one-dimensional confined spaces for the subsequent in situ assembly of luminescent LnCs. The confined LnCs are termed nanoparticles (NPs) to distinguish them from the pure LnCs. Secondary micropores with predictable sizes are successfully formed between the walls of the nanochannels and the orderly aligned NPs therein. By using a small organic ligand that can efficiently sensitize Ln(iii) cations in the assembly processes, the obtained composites show high quantum yields above 20%. The fluorescence can even be effectively maintained across nine pH units. The secondary micropores further enable the unambiguous discrimination of six methinehalides and ultrasensitive detection of uranyl ions. This study provides a new type of luminescent material that has potential for sensing and light emitting.

Detection of bile acids in small volume human bile samples via an amino metal-organic framework composite based solid-phase microextraction probe.

In recent years, bile acids (BAs), the important component of bile, were found closely related to the occurrence and development of diseases, therefore, determination of BAs in bile samples is of great significance. However, biological matrix complexity and low concentrations of BAs were still challenging for BA detection in small amount of bile samples. In this work, a core-shell NH2-MIL101@mSiO2 was designed to improve the capture ability of BAs in biological samples, as well as possess good biocompatibility. Subsequently, solid-phase microextraction (SPME) probe of the NH2-MIL101@mSiO2 was coupled with HPLC-MS/MS to establish the analysis method for detecting eight BAs in bile samples. The established method received extraction efficiencies of (30-2143)-fold higher than those of the commercial probes and low limit of detection (LOD ≤ 0.21 ng mL-1). The miniaturization of SPME sampling devices, as well as the low LOD of this work, endowed this method advantage of low consumption of bile samples (30 µL). Based on the proposed method, eight BAs in bile samples of pancreatic cancer patients and cholelithiasis patients were detected successfully. A distinct difference was found in the concentrations of four targeted BAs in bile samples from pancreatic cancer patients and cholelithiasis patients. This work provided a method for quantification of eight BAs in small volume human bile samples, and it could open up a perspective regarding the relationship between BA metabolism and the occurrence of diseases.

Identifying a selective oligopeptide clamp in the gas phase.

Oligopeptide foldamers are promising as minimalist functional analogues to proteins. Herein, we report a versatile and cost-effective experimental scheme in the gas phase that can facilely identify selective oligopeptides and unambiguously resolve the corresponding folding conformations. Based on this methodology, a stereoselective oligopeptide clamp targeting ß2-blockers is successfully identified.