A Radio-Pharmaceutical Fluorescent Probe for Synergistic Cancer Radiotherapy and Ratiometric Imaging of Tumor Reactive Oxygen Species

Radiotherapy (RT) is an effective and widely applied cancer treatment strategy in clinic. However, it usually suffers from radioresistance of tumor cells and severs side effects of excessive radiation dose. Therefore, it is highly significant to improve radiotherapeutic performance and monitor real-time tumor response, achieving precise and safe RT. Herein, an X-ray responsive radio-pharmaceutical molecule containing chemical radiosensitizers of diselenide and nitroimidazole (BBT-IR/Se-MN) is reported. BBT-IR/Se-MN exhibits enhanced radiotherapeutic effect via a multifaceted mechanisms and self-monitoring ROS levels in tumors during RT. Under X-ray irradiation, the diselenide produces high levels of ROS, leading to enhanced DNA damage of cancer cell. Afterwards, the nitroimidazole in the molecule inhibits the damaged DNA repair, offering a synergetic radiosensitization effect of cancer. Moreover, the probe shows low and high NIR-II fluorescence ratios in the absence and presence of ROS, which is suitable for precise and quantitative monitoring of ROS during sensitized RT. The integrated system is successfully applied for radiosensitization and the early prediction of in vitro and in vivo RT efficacy.     

Activatable Near-Infrared Versatile Fluorescent and Chemiluminescent Dyes Based on the Dicyanomethylene-4H-pyran Scaffold: From Design to Imaging and Theranostics

Activatable fluorescent and chemiluminescent dyes with near-infrared emission have indispensable roles in the fields of bioimaging, molecular prodrugs, and phototheranostic agents. As one of the most popular fluorophore scaffolds, the dicyanomethylene-4H-pyran scaffold has been applied to fabricate a large number of versatile activatable optical dyes for analytes detection and diseases diagnosis and treatment by virtue of its high photostability, large Stokes shift, considerable two-photon absorption cross-section, and structural modifiability. This review discusses the molecular design strategies, recognition mechanisms, and both in vitro and in vivo bio-applications (especially for diagnosis and therapy of tumors) of activatable dicyanomethylene-4H-pyran dyes. The final section describes the current shortcomings and future development prospects of this topic.     

Molecular Dipole Engineering of Carbonyl Additives for Efficient and Stable Perovskite Solar Cells

Carbonyl functional materials as additives are extensively applied to reduce the defects density of the perovskite film. However, there is still a lack of comprehensive understanding for the effect of carbonyl additives to improve device performance. In this work, we systematically study the effect of carbonyl additive molecules on the passivation of defects in perovskite films. After a comprehensive investigation, the results confirm the importance of molecular dipole in amplifying the passivation effect of additive molecules. The additive with strong molecular dipole possesses the advantages of enhancing the efficiency and stability of perovskite solar cells (PSCs). After optimization, the companion efficiency of PSCs is 23.20 %, and it can maintain long-term stability under harsh conditions. Additionally, a large-area solar cell module-modified DLBA was 20.18 % (14 cm²). This work provides an important reference for the selection and designing of efficient carbonyl additives.     

A fluorescent "turn-on" probe for the dual-channel detection of Hg(II) and Mg(II) and its application of imaging in living cells

A novel rhodamine-based fluorescent chemosensor (RND) was synthesized that contains two independent fluorophores and acts as a very sensitive, selective and reversible off-on probe for Hg(II). Importantly, this newly developed sensing system exhibited different fluorescent responses toward Hg(II) and Mg(II) at 589 nm and 523 nm, respectively. RND also displayed detectable color change upon treatment with Hg(II). Results from confocal laser scanning microscopy experiments demonstrated that this chemosensor is cell permeable and can be used as a fluorescent probe for monitoring Hg(II) or Mg(II) in living cells. This probe can also indirectly detect glutathione (GSH) and cysteine (Cys) with good linear relationships.     

Optimized Fluorescent Probe for Specific Imaging of Glutathione S‐Transferases in Living Cells and Mice

GSTP1 has been considered to be a marker for malignancy in many tissues. However, the existing GST fluorescent probes are unfavorable for in vivo imaging because of the limited emission wavelength or insufficient fluorescence enhancement (six‐fold). The limited fluorescence enhancement of GST fluorescent probes is mainly ascribed to the high background signals resulting from the spontaneous reaction between GSH and the probes. In this work, a highly specific GST probe with NIR emission has been successfully developed through optimization of the essential unit of the probe to repress the spontaneous reaction. The novel GST probe exhibits over 100‐fold fluorescence enhancement upon incubation with GSTP1/GSH and high selectivity over other potential interference. In addition, the probe has been proved to be capable of tracking endogenous GST in A549 cells. Finally, the in vivo imaging results demonstrate that the probe can be used for effective imaging of endogenous GST activity in subcutaneous tumor mouse with high contrast.     

Active Layer Morphology Engineering of All-polymer Solar Cells by Systematically Tuning Molecular Weights of Polymer Donors/Acceptors

In all-polymer solar cells (APSCs),number-average molecular weights (Mns) of polymer donors and polymer acceptors play an important role in active layer morphology and photovoltaic performance.In this work,based on a series of APSCs with power conversion efficiency of approaching 10％,we study the effect of Mns of both polymer donor and polymer acceptor on active layer morphology and photovoltaic performance of APSCs.We select poly[4-(5-(4,8-bis(5-((2-butyloctyl)thio)thiophen-2-yl)-6-methylbenzo[1,2-b:4,5-b']dithiophen-2-yl)thiophen-2-yl)-5,6-difluoro-2-(2-hexyldecyl)-7-(5-methylthiophen-2-yl)-2H-benzo[d][1,2,3]triazole](CD1) as the polymer donor and poly[4-(5-(5,10-bis(2-dodecylhexadecyl)-4,4,g,9-tetrafluuoro-7-methyl-4,5,9,10-tetrahydro3a,5,8,10-tetraaza-4,g-diborapyren-2-yl)thiophen-2-yl)-7-(5-methylthiophen-2-yl)benzo[c][1,2,5]thiadiazole](PBN-14) as the polymer acceptor.The Mns of polymer donor CD1 are 14.0,35.5 and 56.1 kg/mol,respectively,and the Mns of polymer acceptor PBN-14 are 32.7,72.4 and 103.4 kg/mol,respectively.To get the desired biscontinueous fibrous network morphololgy of the polymer donor/polymer acceptor blends,at least one polymer should have high or medium Mn.Moreover,when the Mn of polymer acceptor is high,the active layer morphology and APSC device performance are insensitive to the Mn of polymer donor.The optimal APSC device performance is obtained when the Mn of both the polymer donor and the polymer acceptor are medium.These results provide a comprehensive and deep understanding on the interplay and the effect of Mn of polymer donors and polymer acceptors in high-performance APSCs.     

A TriPPPro-Nucleotide Reporter with Optimized Cell-Permeable Dyes for Metabolic Labeling of Cellular and Viral DNA in Living Cells

The metabolic labeling of nucleic acids in living cells is highly desirable to track the dynamics of nucleic acid metabolism in real-time and has the potential to provide novel insights into cellular biology as well as pathogen-host interactions. Catalyst-free inverse electron demand Diels–Alder reactions (iEDDA) with nucleosides carrying highly reactive moieties such as axial 2-trans-cyclooctene (2TCOa) would be an ideal tool to allow intracellular labeling of DNA. However, cellular kinase phosphorylation of the modified nucleosides is needed after cellular uptake as triphosphates are not membrane permeable. Unfortunately, the narrow substrate window of most endogenous kinases limits the use of highly reactive moieties. Here, we apply our TriPPPro (triphosphate pronucleotide) approach to directly deliver a highly reactive 2TCOa-modified 2′-deoxycytidine triphosphate reporter into living cells. We show that this nucleoside triphosphate is metabolically incorporated into de novo synthesized cellular and viral DNA and can be labeled with highly reactive and cell-permeable fluorescent dye-tetrazine conjugates via iEDDA to visualize DNA in living cells directly. Thus, we present the first comprehensive method for live-cell imaging of cellular and viral nucleic acids using a two-step labeling approach.     

Monitoring the Progression of Early Atherosclerosis Using a Fluorescence Nanoprobe for the Detection and Imaging of Phosphorylation and Glucose Levels

Monitoring the early stage of atherosclerosis (AS) without plaque formation is of great significance. Herein, we developed a metal organic framework (MOF)-based fluorescence nanoprobe to analyze the progression of AS by assessing the levels of protein phosphorylation and glucose in blood and tissue. The probe was prepared by post-modification of the MOF with iodine (I₃⁻)-rhodamine B (RhB) associate, which realizes the specific recognition of target object through the metal joint Zr^IV and I₃⁻-RhB, respectively. We investigated different stages of target object changes in the early non-plaque stage of AS in blood. It was found that the levels of phosphate and glucose in the blood were higher than those of the normal mice. The results of two-photon images showed that early AS mice had higher levels of protein phosphorylation and glucose than that of the normal mice. The present study provides a suitable fluorescence tool for further revealing the pathogenesis and progression of AS.     

Improved Stabilities of Labeling Probes for the Selective Modification of Endogenous Proteins in Living Cells and In Vivo

To date, various affinity-based protein labeling probes have been developed and applied in biological research to modify endogenous proteins in cell lysates and on the cell surface. However, the reactive groups on the labeling probes are also the cause of probe instability and nonselective labeling in a more complex environment, e. g., intracellular and in vivo. Here, we show that labeling probes composed of a sterically stabilized difluorophenyl pivalate can achieve efficient and selective labeling of endogenous proteins on the cell surface, inside living cells and in vivo. As compared with the existing protein labeling probes, probes with the difluorophenyl pivalate exhibit several advantages, including long-term stability in stock solutions, resistance to enzymatic hydrolysis and can be customized easily with diverse fluorophores and protein ligands. With this probe design, endogenous hypoxia biomarker in living cells and nude mice were successfully labeled and validated by in vivo, ex vivo, and immunohistochemistry imaging.     

Color Tuning of the Aggregation‐Induced Emission of Maleimide Dyes by Molecular Design and Morphology Control

Aggregation‐induced emission (AIE)‐active maleimide dyes, namely, 2‐p‐toluidino‐N‐p‐tolylmaleimide, 3‐phenyl‐2‐toluidino‐N‐p‐tolylmaleimide, 2‐p‐thiocresyl‐3‐p‐toluidino‐N‐p‐tolylmaleimide, and 2,3‐dithiocresyl‐N‐arylmaleimides, were synthesized by facile synthetic procedures. The dyes show intense emission in the solid state, and emission colors were controlled from green (λ_max=527 nm) to orange (λ_max=609 nm) by varying the substituents at the 2‐ and 3‐positions of the maleimide and the packing structures in the solid state. 2,3‐Disubstituted maleimide dyes effectively underwent redshifts of their emission wavelength. Furthermore, some of the dyes exhibited mechanochromism and polymorphism, and their emission properties were dramatically dependent on the morphology of the solid samples. The mechanisms of the emission behaviors were investigated by X‐ray diffraction. The substituent of the nitrogen atom of the maleimide ring affected the intermolecular interactions and short contacts, which were observed by single crystal X‐ray crystallography, to result in completely different emission properties.     

Multifunctionalized CMCht/PAMAM Dendrimer Nanoparticles Modulate the Cellular Uptake by Astrocytes and Oligodendrocytes in Primary Cultures of Glial Cells

The efficiency of the treatments involving CNS disorders is commonly diminished by the toxicity, reduced stability and lack of targeting of the administered neuroactive compounds. In this study, we have successfully multifunctionalized CMCht/PAMAM dendrimer nanoparticles by coupling the CD11b antibody and loading MP into the nanoparticles. The modification of the new antibody‐conjugated nanoparticles was confirmed by S‐TEM observation and ¹H NMR and FTIR spectroscopy. Cytotoxicity assays revealed that the conjugates did not affect the viability of both primary cultures of glial and microglial cells. Trace analyses of FITC‐labelled nanoparticles revealed that the uptake of antibody‐conjugated nanoparticles was conserved in microglial cells but significantly decreased in astrocytes and oligodendrocytes. Thus, this study demonstrates that antibody conjugation contributes to a modulation of the internalization of these nanocarriers by different cell types, which might be of relevance for specific targeting of CNS cell populations.

     

Suppressed Migration and Enhanced Cisplatin Chemosensitivity in Human Cancer Cell Lines by Tuning the Molecular Mobility of Supramolecular Biomaterials

Cancer cells recognize physical cues transmitted from the surrounding microenvironment, and accordingly alter the migration and chemosensitivity. Cell adhesive biomaterials with tunable physical properties can contribute to the understanding of cancer cell responses, and development of new cancer therapies. Previously, it was reported that polyrotaxane-based surfaces with molecular mobility effectively modulate cellular functions via the yes-associated protein (YAP)-related signaling pathway. In the present study, the impact of molecular mobility of polyrotaxane surfaces on the migration and chemosensitivity of lung (A549), pancreatic (BxPC-3), and breast cancer (MDA-MB-231) cell lines is investigated, and it is found that the cellular spreading of adherent A549 and BxPC-3 cells and nuclear YAP translocation are promoted on low-mobility surfaces, suggesting that cancer cells alter their subcellular YAP localization in response to molecular mobility. Furthermore, low-mobility surfaces suppress cellular migration more than high-mobility surfaces. Additionally, low-mobility surfaces promote the cisplatin chemosensitivity of each cancer cell line to a greater extent than high-mobility surfaces. These results suggest that the molecular mobility of polyrotaxane surfaces suppresses cellular migration and enhances chemosensitivity via the subcellular translocation of YAP in cancer cells. Biointerfaces based on polyrotaxanes can thus be a new platform for elucidating cancer cell migration and chemoresistance mechanisms.     

Emerging Molecular Receptors for the Specific-Target Delivery of Ruthenium and Gold Complexes into Cancer Cells

Cisplatin and derivatives are highly effective in the treatment of a wide range of cancer types; however, these metallodrugs display low selectivity, leading to severe side effects. Additionally, their administration often results in the development of chemoresistance, which ultimately results in therapeutic failure. This scenario triggered the study of other transition metals with innovative pharmacological profiles as alternatives to platinum, ruthenium- (e.g., KP1339 and NAMI-A) and gold-based (e.g., Auranofin) complexes being among the most advanced in terms of clinical evaluation. Concerning the importance of improving the in vivo selectivity of metal complexes and the current relevance of ruthenium and gold metals, this review article aims to survey the main research efforts made in the past few years toward the design and biological evaluation of target-specific ruthenium and gold complexes. Herein, we give an overview of the inorganic and organometallic molecules conjugated to different biomolecules for targeting membrane proteins, namely cell adhesion molecules, G-protein coupled receptors, and growth factor receptors. Complexes that recognize the progesterone receptors or other targets involved in metabolic pathways such as glucose transporters are discussed as well. Finally, we describe some complexes aimed at recognizing cell organelles or compartments, mitochondria being the most explored. The few complexes addressing targeted gene therapy are also presented and discussed.     

Paclitaxel‐Loaded Stabilizer‐Free Poly(D,L‐lactide‐co‐glycolide) Nanoparticles Conjugated with Quantum Dots for Reversion of Anti‐Cancer Drug Resistance and Cancer Cellular Imaging

We prepared the PLGA‐loaded anti‐cancer drug and coated it with quantum dots to make it a dual‐function nanoparticles, and analyzed its potential use in cellular imaging and curing cancers. Two cancer cell lines, paclitaxel‐sensitive KB and paclitaxel‐resistant KB paclitaxel‐50 cervical carcinoma cells, were the relativistic models for analysis of the cytotoxicity of free paclitaxel and paclitaxel‐loaded PLGA conjugated with quantum‐dot nanoparticles. The paclitaxel‐loaded PLGA conjugated with quantum dots nanoparticles were significantly more cytotoxic than the free paclitaxel drug in paclitaxel‐resistant KB paclitaxel‐50 cells. This might have been because the cancer cells developed multi‐drug resistance (MDR), which hampered the action of free paclitaxel by pumping its molecules to extracellular areas. Addition of verapamil, a P‐glycoprotein inhibitor, reversed the MDR mechanism and significantly reduced KB paclitaxel‐50 cell viability. As a result, KB paclitaxel‐50 was highly associated with MDR on the cell membrane. The cytotoxicity results indicated that PLGA nanoparticles served as drug carriers and protected the drugs from MDR‐accelerated efflux. Combined quantum dots with PLGA nanoparticles allowed additional functionality for cellular imaging.     

Gold Nanorod/Fe3O4 Nanoparticle “Nano‐Pearl‐Necklaces” for Simultaneous Targeting,Dual‐Mode Imaging,and Photothermal Ablation of Cancer Cells

Perlen auf Gold : Neuartige multifunktionelle Nanopartikel bestehen aus einzelnen Amin‐modifizierten Goldnanostäbchen, an denen Fe₃O₄‐„Perlen“ mit Carboxyendgruppe angebracht sind. Die Partikel eignen sich zur simultanen Erkennung, dualen Bildgebung und photothermischen Ablation von Brustkrebszellen.

     

Targeted Degradation of PD-L1 and Activation of the STING Pathway by Carbon-Dot-Based PROTACs for Cancer Immunotherapy

Proteolysis targeting chimeras (PROTACs) technology is an emerging approach to degrade disease-associated proteins. Here, we report carbon-dot (CD)-based PROTACs (CDTACs) that degrade membrane proteins via the ubiquitin-proteasome system. CDTACs can bind to programmed cell death ligand 1 (PD-L1), recruit cereblon (CRBN) to induce PD-L1 ubiquitination, and degrade them with proteasomes. Fasting-mimicking diet (FMD) is also used to enhance the cellular uptake and proteasome activity. More than 99 % or 90 % of PD-L1 in CT26 or B16-F10 tumor cells can be degraded by CDTACs, respectively. Furthermore, CDTACs can activate the stimulator of interferon genes (STING) pathway to trigger immune responses. Thus, CDTACs with FMD treatment effectively inhibit the growth of CT26 and B16-F10 tumors. Compared with small-molecule-based PROTACs, CDTACs offer several advantages, such as efficient membrane protein degradation, targeted tumor accumulation, immune system activation, and in vivo detection.     

A Comparative Study of Cellular Uptake and Subcellular Localization of Doxorubicin Loaded in Self‐Assemblies of Amphiphilic Copolymers with Pendant Dendron by MDA‐MB‐231 Human Breast Cancer Cells

Previously synthesized amphiphilic diblock copolymers with pendant dendron moieties have been investigated for their potential use as drug carriers to improve the delivery of an anticancer drug to human breast cancer cells. Diblock copolymer (P₇₁D₃)‐based micelles effectively encapsulate the doxorubicin (DOX) with a high drug‐loading capacity (≈95%, 104 DOX molecules per micelle), which is approximately double the amount of drug loaded into the diblock copolymer (P₂₉₆D₁) vesicles. DOX released from the resultant P₇₁D₃/DOX micelles is approximately 1.3‐fold more abundant, at a tumoral acidic pH of 5.5 compared with a pH of 7.4. The P₇₁D₃/DOX micelles also enhance drug potency in breast cancer MDA‐MB‐231 cells due to their higher intracellular uptake, by approximately twofold, compared with the vesicular nanocarrier, and free DOX. Micellar nanocarriers are taken up by lysosomes via energy‐dependent processes, followed by the release of DOX into the cytoplasm and subsequent translocation into the nucleus, where it exert its cytotoxic effect.

     

The Molecular Basis of Different Approaches for the Study of Cancer Stem Cells and the Advantages and Disadvantages of a Three-Dimensional Culture

Cancer stem cells (CSCs) are a rare tumor subpopulation with high differentiation, proliferative and tumorigenic potential compared to the remaining tumor population. CSCs were first discovered by Bonnet and Dick in 1997 in acute myeloid leukemia. The identification and isolation of these cells in this pioneering study were carried out through the flow cytometry, exploiting the presence of specific cell surface molecular markers (CD34⁺/CD38⁻). In the following years, different strategies and projects have been developed for the study of CSCs, which are basically divided into surface markers assays and functional assays; some of these techniques also allow working with a cellular model that better mimics the tumor architecture. The purpose of this mini review is to summarize and briefly describe all the current methods used for the identification, isolation and enrichment of CSCs, describing, where possible, the molecular basis, the advantages and disadvantages of each technique with a particular focus on those that offer a three-dimensional culture.     

Functional Hybrid Molecules for the Visualization of Cancer: PESIN-Homodimers Combined with Multimodal Molecular Imaging Probes for Positron Emission Tomography and Optical Imaging: Suited for Tracking of GRPR-Positive Malignant Tissue**

We describe multimodal imaging probes for gastrin-releasing peptide receptor (GRPR)-specific targeting suited for positron emission tomography and optical imaging (PET/OI), consisting of PESIN (PEG₃-BBN_7-14) dimers connected to multimodal imaging subunits. These multimodal agents comprise a fluorescent dye for OI and the chelator ((1,4,7-triazacyclononane-4,7-diyl)diacetic acid-1-glutaric acid) (NODA-GA) for PET radiometal isotope labelling. Special focus was put on the influence of the used dyes on the properties of the whole bioconjugates. For this, several compounds with different fluorescent dyes and non-dye carrying subunits were synthesized and investigated. As fluorescent dyes, dansyl, NBD, derivatives of fluorescein, coumarin and rhodamine as well as three pyrilium-based dyes were employed. Considerable influence of the charge of the colored unit on hydrophilicity as well as in vitro target receptor binding was observed and classified. High radiochemical yields and purities were found during radiolabeling of the multimodal imaging subunits as well as their GRPR-specific bioconjugates with ⁶⁸Ga. Examinations of the photophysical properties of both molecule species displayed no loss or alteration of fluorescence characteristics.     

A Practical Guide on the Synthesis of Metal Chelates for Molecular Imaging and Therapy by Means of Click Chemistry

The copper‐catalyzed cycloaddition of organic azides and alkynes (CuAAC) is one of the most popular reactions for rapid assembly of multifunctional molecular frameworks from commercially available building blocks. It is also attractive for synthesis of conjugates of multidentate chelate ligands (chelators) with molecular targeting vectors, such as peptides or proteins, which serve as precursors for labeling with metal radionuclides or are useful as MRI contrast agents after Gd^III complexation. However, applicability of CuAAC for such purposes is complicated by formation of unwanted copper chelates. The alternative use of copper‐free click chemistry, for example, the strain‐promoted alkyne‐azide cycloaddition (SPAAC) or the Diels–Alder reaction of tetrazines and strained alkenes, entails other specific challenges: Introduction of large, isomerically non‐homogeneous and hydrophobic linker groups affects product homogeneity and can severely change pharmacokinetic profiles. Against this background, this review elucidates scope and applicability of both Cu‐catalyzed and Cu‐free alkyne‐azide cycloadditions pertinent to the elaboration of radiometal chelates and MRI contrast agents, with an emphasis on strategies to tackle the problem of copper complexation during CuAAC.