Latest ArticlesChemical modification of native peptides and proteins is a versatile strategy to facilitate late-stage diversification for functional studies. Among the proteogenic amino acids, lysine is extensively involved in post-translational modifications and the binding of ligands to target proteins, making its selective modification attractive. However, lysine’s high natural abundance and solvent accessibility, as well as its relatively low reactivity to cysteine, necessitate addressing chemoselectivity and regioselectivity for the Lys modification of native proteins. Although Lys chemoselective modification methods have been well developed, achieving site-selective modification of a specific Lys residue remains a great challenge. In this review, we discussed the challenges of Lys selective modification, presented recent examples of Lys chemoselective modification, and summarized the currently known methods and strategies for Lys site-selective modification. We also included an outlook on potential solutions for Lys site-selective labeling and its potential applications in chemical biology and drug development.
Interstitial hypertension and extracellular matrix (ECM) barriers imposed by cancer-associated fibroblasts (CAFs) at the tumor site significantly impede the retention of intratumorally administered oncolytic viruses (OVs) as well as their efficacy in infecting and eradicating tumor cells. Herein, a stable, controllable, and easily prepared hydrogel was developed for employing a differential release strategy to deliver OVs. The oncolytic herpes simplex virus-2 (oH2) particles were loaded within sodium alginate (ALG), together with the small molecule drug PT-100 targeting CAFs. The rapid release of PT-100 functions as an anti-CAFs agent, reducing ECM, and alleviating interstitial pressure at the tumor site. Consequently, the delayed release of oH2 could more effectively invade and eradicate tumor cells while also facilitating enhanced infiltration of immune cells into the tumor microenvironment, thereby establishing an immunologically favorable milieu against tumors. This approach holds significant potential for achieving highly efficient oncolytic virus therapy with minimal toxicity, particularly in tumors rich in stromal components.
The overuse of surfactants has made them well-known environmental pollutants. So far, it is still a challenge to simultaneously distinguish cationic, anionic, zwitterionic, nonionic surfactants and surfactants with similar structures based on traditional analytical techniques. We developed a high-throughput method for distinguishing various surfactants based on the adaptive emission profile as fingerprints (AEPF). The fluorescence response of the sensor was based on the interaction between surfactants and 1,3-diacetylpyrene (o-DAP) probe. The interaction affected the reversible conversion of free molecules and two aggregates in the solution, thereby changing the relative abundance and the fluorescence intensity ratio of two aggregates emitting different fluorescence. The o-DAP sensor can distinguish four types of surfactants (16 surfactants), especially surfactants of the same type with similar structures. The o-DAP sensor sensitively determined the critical micelle concentration (CMC) of 16 surfactants based on the interaction between o-DAP and surfactants. Additionally, the o-DAP sensor can detect and distinguish artificial vesicles made from different surfactants.
Singlet oxygen (1O2), as the primary reactive oxygen species in photodynamic therapy, can effectively induce excessive oxidative stress to ablate tumors and kill germs in clinical treatment. However, monitoring endogenous 1O2 is greatly challenging due to its extremely short lifetime and high reactivity in biological condition. Herein, we report an ultra-high signal-to-ratio near-infrared chemiluminescent probe (DCM-Cy) for the precise detection of endogenous 1O2 during photodynamic therapy (PDT). The methoxy moiety was removed from enolether unit in DCM-Cy to suppress the potential self-photooxidation reaction, thus greatly eliminating the photoinduced background signals during PDT. Additionally, the compact cyclobutane modification of DCM-Cy resulted in a significant 6-fold increase in cell permeability compared to conventional adamantane-dioxane probes. Therefore, our "step-by-step" strategy for DCM-Cy addressed the limitations of traditional chemiluminescent (CL) probes for 1O2, enabling effectively tracking of endogenous 1O2 level changes in living cells, pathogenic bacteria and mice in PDT.
Constructing multi-dimensional hydrogen bond (H-bond) regulated single-molecule systems with multi-emission remains a challenge. Herein, we report the design of a new excited-state intramolecular proton transfer (ESIPT) featured chromophore (HBT-DPI) that shows flexible emission tunability via the multi-dimensional regulation of intra- and intermolecular H-bonds. The feature of switchable intramolecular H-bonds is induced via incorporating several hydrogen bond acceptors and donors into one single HBT-DPI molecule, allowing the "turn on/off" of ESIPT process by forming isomers with distinct intramolecular H-bonds configurations. In response to different external H-bonding environments, the obtained four types of crystal/cocrystals vary in the contents of isomers and the molecular packing modes, which are mainly guided by the intermolecular H-bonds, exhibiting non-emissive features or emissions ranging from green to orange. Utilizing the feature of intermolecular H-bond guided molecular packing, we demonstrate the utility of this fluorescent material for visualizing hydrophobic/hydrophilic areas on large-scale heterogeneous surfaces of modified poly(1,1-difluoroethylene) (PVDF) membranes and quantitatively estimating the surface hydrophobicity, providing a new approach for hydrophobicity/hydrophilicity monitoring and measurement. Overall, this study represents a new design strategy for constructing multi-dimensional hydrogen bond regulated ESIPT-based fluorescent materials that enable multiple emissions and unique applications.
Lateral flow immunoassay (LFIA), a rapid detection technique noted for simplicity and economy, has showcased indispensable applicability in diverse domains such as disease screening, food safety, and environmental monitoring. Nevertheless, challenges still exist in detecting ultra-low concentration analytes due to the inherent sensitivity limitations of LFIA. Recently, significant advances have been achieved by integrating enzyme activity probes and transforming LFIA into a highly sensitive tool for rapidly detecting trace analyte concentrations. Specifically, modifying natural enzymes or engineered nanozymes allows them to function as immune probes, directly catalyzing the production of signal molecules or indirectly initiating enzyme activity. Therefore, the signal intensity and detection sensitivity of LFIA are markedly elevated. The present review undertakes a comprehensive examination of pertinent research literature, offering a systematic analysis of recently proposed enzyme-based signal amplification strategies. By way of comparative assessment, the merits and demerits of current approaches are delineated, along with the identification of research avenues that still need to be explored. It is anticipated that this critical overview will garner considerable attention within the biomedical and materials science communities, providing valuable direction and insight toward the advancement of high-performance LFIA technologies.
Diseases associated with bacterial infection, especially those caused by gram-negative bacteria, have been posing a serious threat to human health. Photodynamic therapy based on aggregation-induced emission (AIE) photosensitizer have recently emerged and provided a promising approach for bacterial discrimination and efficient photodynamic antimicrobial applications. However, they often suffer from the shorter excitation wavelength and lower molar extinction coefficients in the visible region, severely limiting their further applications. Herein, three novel BF2-curcuminoid-based AIE photosensitizers, TBBC, TBC and TBBC-C8, have been rationally designed and successfully developed, in which OCH3- and OC8H17-substituted tetraphenylethene (TPE) groups serve as both electron donor (D) and AIE active moieties, BF2bdk group functions as electron acceptor (A), and styrene (or ethylene) group as π-bridge in this D-π-A-π-D system, respectively. As expected, these resulting BF2-curcuminoids presented solvent-dependent photophysical properties with large molar extinction coefficients in solutions and excellent AIE properties. Notably, TBBC showed an effective singlet oxygen generation efficiency thanks to the smaller singlet-triplet energy gap (ΔEST), and remarkable photostability under green light exposure at 530 nm (8.9 mW/cm2). More importantly, TBBC was demonstrated effectiveness in selective staining and photodynamic killing of Escherichia coli (E. coli) in vitro probably due to its optimal molecular size compared with TBC and TBBC-C8. Therefore, TBBC will have great potential as a novel AIE photosensitizer to apply in the discrimination and selective sterilization between Gram-positive and Gram-negative bacteria.
Designing advanced hydrogels with controlled mechanical properties, drug delivery manner and multifunctional properties will be beneficial for biomedical applications. However, the further development of hydrogel is limited due to its poor mechanical property and structural diversity. Hydrogels combined with polymeric micelles to obtain micelle-hydrogel composites have been designed for synergistic enhancement of each original properties. Incorporation polymeric micelles into hydrogel networks can not only enhance the mechanical property of hydrogel, but also expand the functionality of hydrogel. Recent advances in polymeric micelle-hydrogel composites are herein reviewed with a focus on three typical micelle incorporation methods. In this review, we will also highlight some emerging biomedical applications in developing micelle-hydrogel composite with multiple functionalities. In addition, further development and application prospects of the micelle-hydrogels composites have also been addressed.
Diabetic kidney disease (DKD) is recognized as a severe complication in the development of diabetes mellitus (DM), posing a significant burden for global health. Major characteristics of DKD kidneys include tubulointerstitial oxidative stress, inflammation, excessive extracellular matrix deposition, and progressing renal fibrosis. However, current treatment options are limited and cannot offer enough efficacy, thus urgently requiring novel therapeutic approaches. Tetrahedral framework nucleic acids (tFNAs) are a novel type of self-assembled DNA nanomaterial with excellent structural stability, biocompatibility, tailorable functionality, and regulatory effects on cellular behaviors. In this study, we established an in vitro high glucose (HG)-induced human renal tubular epithelial cells (HK-2 cells) pro-fibrogenic model and explored the antioxidative, anti-inflammatory, and antifibrotic capacity of tFNAs and the potential molecular mechanisms. tFNAs not only effectively alleviated oxidative stress through reactive oxygen species (ROS)-scavenging and activating the serine and threonine kinase (Akt)/nuclear factor erythroid 2-related factor 2 (Nrf2)/heme oxygenase-1 (HO-1) signaling pathway but also inhibited the production of pro-inflammatory factors such as tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), and interleukin-6 (IL-6) in diabetic HK-2 cells. Additionally, tFNAs significantly downregulated the expression of Collagen I and α-smooth muscle actin (α-SMA), two representative biomarkers of pro-fibrogenic myofibroblasts in the renal tubular epithelial-mesenchymal transition (EMT). Furthermore, we found that tFNAs exerted this function by inhibiting the Wnt/β-catenin signaling pathway, preventing the occurrence of EMT and fibrosis. The findings of this study demonstrated that tFNAs are naturally endowed with great potential to prevent fibrosis progress in DKD kidneys and can be further combined with emerging pharmacotherapies, providing a secure and efficient drug delivery strategy for future DKD therapy.
Glioma is a severe malignant brain tumor marked by an exceedingly dire prognosis and elevated incidence of recurrence. The resilience of such tumors to chemotherapeutic agents, coupled with the formidable obstacle the blood-brain barrier (BBB) presents to most pharmacological interventions are major challenges in anti-glioma therapy. In an endeavor to surmount these impediments, we have synergized pH-sensitive nanoparticles carrying doxorubicin and apatinib to amplify the anti-neoplastic efficacy with cyclic arginine–glycine–aspartate acid (cRGD) modification. In this study, we found that the combination of doxorubicin (DOX) and apatinib (AP) showed a significant synergistic effect, achieved through cytotoxicity and induction of apoptosis, which might be due to the increased intracellular uptake of DOX following AP treatment. Besides, polycaprolactone-polyethylene glycol-cRGD (PCL-PEG-cRGD) drug carrier could cross the BBB by its targeting ability, and then deliver the drug to the glioma site via pH-responsive release, increasing the concentration of the drugs in the tumor. Meanwhile, DOX/AP-loaded PCL-PEG-cRGD nanoparticles effectively inhibited cell proliferation, enhanced glioma cell apoptosis, and retarded tumor growth in vivo. These results collectively identified DOX/AP-loaded PCL-PEG-cRGD nanoparticles as a promising therapeutic candidate for the treatment of glioma.
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