N‑Doped Graphene: An Alternative Carbon-Based Matrix for Highly Efficient Detection of Small Molecules by Negative Ion MALDI-TOF MS

Gas-phase N-doped graphene (gNG) was synthesized by a modified thermal annealing method using gaseous melamine as nitrogen source and then for the first time applied as a matrix in negative ion matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) for small molecule analysis. Unlike the complicated adducts produced in positive ion mode, MS spectra obtained on gNG matrix in negative ion mode was only featured by deprotonated molecule ion peaks without matrix interference. By the gNG assisted desorption/ionization (D/I) process, some applications were carried out on a wide range of low-molecular weight (MW) analytes including amino acids, fatty acids, peptides, anabolic androgenic steroids as well as anticancer drugs, with an extraordinary laser desorption/ionization (LDI) efficiency over traditional α-cyano-4-hydroxycinnamic acid (CHCA) and other carbon-based materials in the negative ion detection mode. By comparison of a series of graphene-based matrixes, two main factors of matrix gNG were unveiled to play a decisive role in assisting negative ion D/I process: a well-ordered π-conjugated system for laser absorption and energy transfer; pyridinic-doped nitrogen species functioning as deprotonation sites for proton capture on negative ionization. The good salt tolerance and high sensitivity allowed further therapeutic monitoring of anticancer drug nilotinib in the spiked human serum, a real case of biology. Signal response was definitely obtained between 1 mM and 1 μM, meeting the demand of assessing drug level in the patient serum. This work creates a new application branch for nitrogen-doped graphene and provides an alternative solution for small molecule analysis

Multiplexed Quantitative MALDI MS Approach for Assessing Activity and Inhibition of Protein Kinases Based on Postenrichment Dephosphorylation of Phosphopeptides by Metal–Organic Framework-Templated Porous CeO₂

Protein kinase is regarded as a potential target for anticancer therapeutics due to its relation to many diseases, in which more than one kinase participates in the cell signaling cascades. We herein demonstrate a multiplexed quantitative matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) approach to simultaneously assess the activity and inhibition of multiple protein kinases. In this design, substrate peptides phosphorylated by kinases of interest are specifically harvested by metal–organic framework (MOF)-templated porous CeO₂ and consequently transformed to the dephosphorylated forms due to the phosphatase-like activity of CeO₂, resulting in a unique quantitative MS signal with an enhanced intensity. Based on the peak area ratios of dephosphorylated variants of the phosphorylated product to respective deuterated internal standard, the activity and inhibition of each kinase can be independently profiled. In addition to the accurate characterization of protein kinase A (PKA) activity and inhibition induced by H-89, the multiplexing capability of the MS-based method allowed quantitative evaluation of the activity of Abl and Src, the two tightly associated kinases in the occurrence of chronic myeloid leukemia (CML) in a multiplexed format, exhibiting excellent orthogonality for the dual signal readout channels. Moreover, the inactivation of both Abl and Src by the inhibitor imatinib, dasatinib, and ponatinib was simultaneously traced, giving a whole picture of the competition behavior between the kinases for binding therapeutic molecules. This approach holds great promise in global investigation of kinase signal pathways and high-throughput screening of effective protein kinase inhibitors

“Stealth and Fully-Laden” Drug Carriers: Self-Assembled Nanogels Encapsulated with Epigallocatechin Gallate and siRNA for Drug-Resistant Breast Cancer Therapy

For codelivery of therapeutic genes and chemical agents in combined therapy, the ideal drug delivery system entails high-capacity and low-body toxicity carriers, allowing adequate drug dose for tumor regions while yielding low residues in normal tissues. To augment the gene/drug load capacity and circumvent the potential toxicity brought by traditional inorganic and polymeric nanocarriers, a “stealth” carrier was herein designed in a simple self-assembly of (−)-epigallocatechin-3-<i>O</i>-gallate (EGCG) and small interfering RNA (siRNA) by recruiting protamine as a biodegradable medium for the treatment of drug-resistant triple-negative breast cancer. In the self-assembled nanogel, entrapped siRNA played a central role in sensitizing the tumor response to EGCG-involved chemotherapy, and the positively charged protamine served as the assembly skeleton to fully accommodate gene and drug molecules and minimize the factors causing side effects. As compared to stand-alone chemotherapy with EGCG, the multicomponent nanogel revealed a 15-fold increase in the cytotoxicity to drug-resistant MDA-MB-231 cell line. Moreover, equipped with hyaluronic acid and tumor-homing cell-penetrating peptide as the outmost targeting ligands, the siRNA- and EGCG-loaded nanogel demonstrates superior selectivity and tumor growth inhibition to free EGCG in xenograft MDA-MB-231 tumor-bearing mice. Meanwhile, thanks to the acknowledged biosafety of protamine, little toxicity was found to normal tissues and organs in the animal model. This gene/drug self-assembly caged in a biodegradable carrier opens up an effective and secure route for drug-resistant cancer therapy and provides a versatile approach for codelivery of other genes and drugs for different medical purposes

Enriching Reaction Intermediates in Multishell Structured Copper Catalysts for Boosted Propanol Electrosynthesis from Carbon Monoxide

Fine-tuned catalysts that alter the diffusion kinetics of reaction intermediates is of great importance for achieving high-performance multicarbon (C2+) product generation in carbon monoxide (CO) reduction. Herein, we conduct a structural design based on Cu2O nanoparticles and present an effective strategy for enhancing propanol electrosynthesis from CO. The electrochemical characterization, operando Raman monitoring, and finite-element method simulations reveal that the multishell structured catalyst can realize the enrichment of C1 and C2 intermediates by nanoconfinement space, leading to the possibility of further coupling. Consequently, the multishell copper catalyst realizes a high Faraday efficiency of 22.22 ± 0.38% toward propanol at the current density of 50 mA cm–2

Single Gold@Silver Nanoprobes for Real-Time Tracing the Entire Autophagy Process at Single-Cell Level

This article describes a multimodified core–shell gold@silver nanoprobe for real-time monitoring the entire autophagy process at single-cell level. Autophagy is vital for understanding the mechanisms of human pathologies, developing novel drugs, and exploring approaches for autophagy controlling. A major challenge for autophagy study lies in real-time monitoring. One solution might come from real-time detection of in situ superoxide radicals (O₂^•–), because it is the main regulator of autophagy. In this work, our proposed nanoprobes were etched by O₂^•– and gave a notable wavelength change in the plasmon resonance scattering spectra. Both the experimental and simulated results suggested the wavelength change rate correlated well with O₂^•– level. This response enabled its application in real-time in situ quantification of O₂^•– during autophagy course. More importantly, with the introduction of “relay probe” operation, two types of O₂^•–-regulating autophagy processes were successfully traced from the beginning to the end, and the possible mechanism was also proposed

<i>In Situ</i> Amplification of Intracellular MicroRNA with MNAzyme Nanodevices for Multiplexed Imaging, Logic Operation, and Controlled Drug Release

MicroRNAs (miRNAs), as key regulators in gene expression networks, have participated in many biological processes, including cancer initiation, progression, and metastasis, indicative of potential diagnostic biomarkers and therapeutic targets. To tackle the low abundance of miRNAs in a single cell, we have developed programmable nanodevices with MNAzymes to realize stringent recognition and <i>in situ</i> amplification of intracellular miRNAs for multiplexed detection and controlled drug release. As a proof of concept, miR-21 and miR-145, respectively up- and down-expressed in most tumor tissues, were selected as endogenous cancer indicators and therapy triggers to test the efficacy of the photothermal nanodevices. The sequence programmability and specificity of MNAzyme motifs enabled the fluorescent turn-on probes not only to sensitively profile the distributions of miR-21/miR-145 in cell lysates of HeLa, HL-60, and NIH 3T3 (9632/0, 14147/0, 2047/421 copies per cell, respectively) but also to visualize trace amounts of miRNAs in a single cell, allowing logic operation for graded cancer risk assessment and dynamic monitoring of therapy response by confocal microscopy and flow cytometry. Furthermore, through general molecular design, the MNAzyme motifs could serve as three-dimensional gatekeepers to lock the doxorubicin inside the nanocarriers. The drug nanocarriers were exclusively internalized into the target tumor cells <i>via</i> aptamer-guided recognition and reopened by the endogenous miRNAs, where the drug release rates could be spatial-temporally controlled by the modulation of miRNA expression. Integrated with miRNA profiling techniques, the designed nanodevices can provide general strategy for disease diagnosis, prognosis, and combination treatment with chemotherapy and gene therapy

Near Infrared-Guided Smart Nanocarriers for MicroRNA-Controlled Release of Doxorubicin/siRNA with Intracellular ATP as Fuel

In chemotherapy, it is a great challenge to recruit endogenous stimuli instead of external intervention for targeted delivery and controlled release; microRNAs are the most promising candidates due to their vital role during tumorigenesis and significant expression difference. Herein, to amplify the low abundant microRNAs in live cells, we designed a stimuli-responsive DNA Y-motif for codelivery of siRNA and Dox, in which the cargo release was achieved <i>via</i> enzyme-free cascade amplification with endogenous microRNA as trigger and ATP (or H⁺) as fuel through toehold-mediated strand displacement. Furthermore, to realize controlled release in tumor cells, smart nanocarriers were constructed with stimuli-responsive Y-motifs, gold nanorods, and temperature-sensitive polymers, whose surfaces could be reversibly switched between PEG and RGD states <i>via</i> photothermal conversion. The PEG corona kept the nanocarriers stealth during blood circulation to protect the Y-motifs against nuclease digestion and enhance passive accumulation, whereas the exposed RGD shell under near-infrared (NIR) irradiation at tumor sites facilitated the specific receptor-mediated endocytosis by tumor cells. Through modulating NIR laser, microRNA, or ATP expressions, the therapy efficacies to five different cell lines were finely controlled, presenting NIR-guided accumulation, massive release, efficient gene silence, and severe apoptosis in HeLa cells; <i>in vivo</i> study showed that a low dosage of nanocarriers synergistically inhibited the tumor growth by silencing gene expression and inducing cell apoptosis under mild NIR irradiation, though they only brought minimum damage to normal organs. The combination of nanomaterials, polymers, and DNA nanomachines provided a promising tool for designing smart nanodevices for disease therapy