We report a solution-based synthesis of monodispersed Cu(2)CdSnSe(4) nanocrystals and a study on the thermoelectric properties of these wide-band-gap dense materials compacted from nanocrystals for the first time. With the help of copper dopants and selenium vacancies generated during wet-chemistry synthesis, a large increment in the power factor is observed, and the dimensionless figure-of-merit ZT reaches a peak value of 0.65 at 450 °C.
Severe acute respiratory syndrome
coronavirus 2 (SARS-CoV-2) utilizes
an extensively glycosylated surface spike (S) protein to mediate host
cell entry, and the S protein glycosylation plays key roles in altering
the viral binding/function and infectivity. However, the molecular
structures and glycan heterogeneity of the new O-glycans found on
the S protein regional-binding domain (S-RBD) remain cryptic because
of the challenges in intact glycoform analysis by conventional bottom-up
glycoproteomic approaches. Here, we report the complete structural
elucidation of intact O-glycan proteoforms through a hybrid native
and denaturing top-down mass spectrometry (MS) approach employing
both trapped ion mobility spectrometry (TIMS) quadrupole time-of-flight
and ultrahigh-resolution Fourier transform ion cyclotron resonance
(FTICR)-MS. Native top-down TIMS-MS/MS separates the protein conformers
of the S-RBD to reveal their gas-phase structural heterogeneity, and
top-down FTICR-MS/MS provides in-depth glycoform analysis for unambiguous
identification of the glycan structures and their glycosites. A total
of eight O-glycoforms and their relative molecular abundance are structurally
elucidated for the first time. These findings demonstrate that this
hybrid top-down MS approach can provide a high-resolution proteoform-resolved
mapping of diverse O-glycoforms of the S glycoprotein, which lays
a strong molecular foundation to uncover the functional roles of their
O-glycans. This proteoform-resolved approach can be applied to reveal
the structural O-glycoform heterogeneity of emergent SARS-CoV-2 S-RBD
variants as well as other O-glycoproteins in general.
Recently, we developed a photo-cleavable surfactant, 4hexylphenylazosulfonate (Azo), for top-down proteomics. [1] Azo is straightforward to synthesize (requiring only two-step synthesis and simple purification), [23] effectively solubilizes proteins (including membrane proteins), and can be rapidly degraded before MS analysis. [1] Herein, for the first time, we demonstrate that Azo is fully compatible with bottom-up proteomics and uniquely serves as an "all-in-one" MScompatible surfactant for both bottom-up and top-down proteomics, which greatly facilitates high-throughput sample
Top-down mass spectrometry (MS)-based proteomics provides a comprehensive analysis of proteoforms to achieve a proteome-wide understanding of protein functions. However, the MS detection of low-abundance proteins from blood remains an unsolved challenge due to the extraordinary dynamic range of the blood proteome. Here, we develop an integrated nanoproteomics method coupling peptide-functionalized superparamagnetic nanoparticles (NPs) with top-down MS for the enrichment and comprehensive analysis of cardiac troponin I (cTnI), a gold-standard cardiac biomarker, directly from serum. These NPs enable the sensitive enrichment of cTnI (<1 ng/mL) with high specificity and reproducibility, while simultaneously depleting highly abundant proteins such as human serum albumin (>10 10 more abundant than cTnI). We demonstrate that top-down nanoproteomics can provide highresolution proteoform-resolved molecular fingerprints of diverse cTnI proteoforms to establish proteoform-pathophysiology relationships. This scalable and reproducible antibodyfree strategy can generally enable the proteoform-resolved analysis of low-abundance proteins directly from serum to reveal previously unachievable molecular details.
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