Search Results (284)

The tumor microenvironment plays an important role in tumor incidence, metastasis, and chemotherapy resistance. Novel therapeutic strategies targeting the tumor microenvironment have become a research focus in the field of biomedicine. In this study, we developed a smart small-molecule probe, TZ2, featuring pH/GSH dual-responsive characteristics. TZ2 exhibits a unique pH-dependent reaction mechanism: GSH is preferentially covalently modified with maleimide groups in acidic microenvironments (pH < 7), while specifically activating nucleophilic substitutions under alkaline conditions (pH > 7). It is worth noting that TZ2 effectively eliminates intracellular glutathione (GSH) in a time and concentration-dependent manner, demonstrating significant GSH depletion ability in various tumor cell lines. Pharmacodynamic studies have shown that TZ2 not only inhibits the cell cycle by regulating the expression of cell cycle-related proteins, but also effectively suppresses the cloning ability of cancer cells. Furthermore, TZ2 significantly increases the sensitivity of drug-resistant cancer cells to cisplatin. By integrating microenvironment modulation, real-time monitoring, and synergistic therapy, TZ2 provides a novel molecular tool and theoretical basis for tumor theranostics integration. Full article

Background: Inflammatory breast cancer (IBC) is a rare and aggressive subtype of breast cancer that accounts for 1–5% of BC patients and regularly affects women under 40 years of age. Approximately 50% of IBC cases are HER2+ and can be treated with the monoclonal antibody-based therapy Herceptin (trastuzumab). However, resistance to Herceptin develops within a year, and effective second-line targeted therapies are currently unavailable for IBC patients. Lipocalin-2 (LCN2) is a promising therapeutic target for IBC due to its role in promoting tumor invasiveness, angiogenesis, and the inflammatory tumor microenvironment characteristic of IBC. Objective: We developed Herceptin-conjugated liposomes loaded with LCN2-targeted small-interference RNA (siRNA) for HER2+ IBCs. Methods: We synthesized DSPE-PEG(2000)-maleimide-Herceptin in a three-step process and formulated the liposomes together with DOPC, PEG(2000)-PE, cholesterol, and siRNA. Results: Dynamic light scattering confirmed the liposome size distribution, which was 66.7 nm for the Herceptin-conjugated liposome versus 43.0 nm in a non-functionalized liposome. Here, we report efficient internalization of this formulation into HER2+ IBC cells, reducing LCN2 levels by 30% and disrupting tumor emboli formation. RNA sequencing revealed 139 genes that were differentially expressed upon LCN2 knockdown, with 25 canonical pathways identified through Ingenuity Pathway Analysis. Conclusions: These findings suggest that LCN2-targeted siRNA within Herceptin-targeted liposomes represents a promising therapeutic strategy for IBC. Full article

The repair efficiency of various self-healing materials often depends on the ability of the prepolymer and curing agent to form mixtures. This paper presents a synthesis and study of the properties of modified self-healing polyurethanes using the Diels–Alder reaction (DA reaction), obtained from a maleimide-terminated preform and a series of furan–urethane curing agents. The most commonly used isocyanates (4,4′-methylene diphenyl diisocyanate (MDI), 2,4-tolylene diisocyanate (TDI), and hexamethylene diisocyanate (HDI)) and furan derivatives (furfurylamine, difurfurylamine, and furfuryl alcohol) were used as initial reagents for the synthesis of curing agents. For comparative analysis, polyurethanes were also obtained using the well-known “traditional” approach—from furan-terminated prepolymers based on mono- and difurfurylamine, as well as furfuryl alcohol and the often-used bismaleimide curing agent 1,10-(methylenedi-1,4-phenylene)bismaleimide (BMI). The structure and composition of all polymers were studied using spectroscopic methods. Molecular mass was determined using gel permeation chromatography (GPC). Thermal properties were studied using TGA, DSC, and TMA methods. The mechanical and self-healing properties of the materials were investigated via a uniaxial tensile test. Visual assessment of the completeness of damage restoration after the self-healing cycle was carried out using a scanning electron microscope. It was shown that the proposed modified approach helps obtain more durable polyurethanes with a high degree of self-healing of mechanical properties after damage. Full article

In the chemistry of bio-based furans, the Diels–Alder reaction plays an important role as a renewable route for the synthesis of fuels, fine chemicals, and monomers. Nonetheless, the unfavorable kinetic and thermodynamic parameters inherent to the Diels–Alder reaction involving furans as dienes often lead to the reversibility of cycloaddition, resulting in decreased equilibrium conversion and diastereoselectivity. In this study, we present a new strategy for overcoming the problem of reversibility in chemical reactions. We demonstrate that conducting the reaction under solvent-free conditions can facilitate the transition from a molten state formed by the initial reactants to a solid phase containing the reaction product along with an excess of the initial substrate. According to our results, such a liquid-to-solid transition of the reaction mixture can lead to exceptionally high conversion and diastereoselectivity in the furan–maleimide Diels–Alder reaction, particularly for challenging electron-poor furanic substrates. Our approach enables the reversible furan–maleimide Diels–Alder reaction to be performed in a cleaner and more environmentally friendly manner, free from the complexities associated with the use of solvents and the need for purification from side products. Full article

Background: Oxidative stress contributes to the activation of muscle protein synthesis after high-intensity resistance exercise (HIRE) or low-intensity resistance exercise combined with blood flow restriction (LIBFR), but it is unclear if this oxidative stress response post-exercise is monophasic or multiphasic. We aimed to answer this question using albumin Cys34 oxidation as an oxidative stress marker. Methods: Seven untrained individuals completed HIRE and LIBFR on separate days. Albumin Cys34 oxidation (total and reversibly and irreversibly oxidized fractions), muscle oxygenation, oxygen consumption (${\dot{\mathrm{V}}\mathrm{O}}_2$), lactate, and heart rate (HR) were measured before and up to 5 h post-exercise. Results: Both HIRE and LIBFR induced a biphasic increase in total oxidized albumin Cys34, with a transient peak in irreversibly oxidized albumin Cys34 immediately post-exercise (p < 0.001) before a delayed sustained increase in reversibly oxidized albumin Cys34, which peaked at 90–120 min and lasted ≥5 h post-exercise (p < 0.05). Muscle oxygenation decreased immediately post-exercise (p < 0.001) before rising above baseline (p < 0.05). ${\dot{\mathrm{V}}\mathrm{O}}_2$, HR, and blood lactate peaked post-exercise (p < 0.001) and returned to baseline within 15–90 min. Irreversibly oxidized albumin Cys34 was positively correlated with lactate and ${\dot{\mathrm{V}}\mathrm{O}}_2$ post-exercise (p < 0.001). Conclusion: Here, we show that resistance exercise, with or without blood flow restriction, results in an early biphasic oxidative stress response after exercise. Full article

In order to find a good candidate for Förster Resonance Energy Transfer (FRET)-mediated X-ray-induced photodynamic therapy (X-PDT) for the treatment of cancer, lanthanide (Ln)-based AGuIX nanoparticles (NPs) conjugated with Rose Bengal (RB) as a photosensitizer (PS) were synthesized. X-PDT overcomes the problem of the poor penetration of visible light into tissues, which limits the efficacy of PDT in the treatment of deep-seated tumors. It is essential to optimize FRET efficiency by maximizing the overlap integral between donor emission and acceptor absorption and lengthening the duration of the donor emission. In this study, we optimized energy transfer between a scintillator (Sc) as a donor and a PS as an acceptor. Terbium (Tb) and Gadolinium (Gd) as Scs and Rose RB as a PS were chosen. The study of energy transfer between Tb, Gd and RB in solution and chelated on AGuIX NPs proved to be FRET-like. RB was conjugated directly onto AGuIX NPs (i.e., AGuIX Ln@RB), and the use of a spacer arm (i.e., AGuIX Ln@spacer arm-RB) increased FRET efficiency. Singlet oxygen production by these NPs was observed under UV–visible illumination and X-ray irradiation. The in vitro bioassay demonstrated 52% cell death of U-251MG derived from human malignant glioblastoma multiforme at a concentration of 1 μM RB after illumination and irradiation (2 Gy, 320 kV, 10 mA, 3 Gy/min at 47 cm). In addition, the RB-coupled NRP-1-targeting peptide (i.e., K(RB)DKPPR) was conjugated onto AGuIX NPs by a thiol-maleimide click chemistry reaction, and an affinity in the nM range was observed. Full article

Poly (styrene-maleic anhydride) copolymers, due to their unique structure, are extensively functionalized and modified for preparing heat stabilizers, compatibilizers, and other functional additives. Using 4-methylpent-1-ene-2,4-diyl diphenyl (α-MSD) as a chain transfer agent, a series of molecular-weight-controlled maleic anhydride-derived styrene copolymers, poly(N-p-fluorophenylmaleimide-alt-styrene) (PFS) and poly(N-p-carboxylphenylmaleimide-alt-styrene) (PCS), were synthesized via free radical copolymerization. The molecular weights of PFS and PCS were adjusted to explore their impact on the properties of PFS/PA6 and PCS/PA6 blends. Gel permeation chromatography (GPC) analysis confirmed that α-MSD effectively regulated the molecular weights of PFS and PCS. PFS and PCS with lower molecular weights exhibited significantly reduced viscosity, with minimal impact on their thermal and mechanical properties. Full article

Marine macroalgae are excellent sources of bioactive compounds recognized by their pharmaceutical and biomedical potential. A subcritical water extraction (SWE) was applied to the macroalga Codium tomentosum, and the extract was used to prepare phytosomes. A Box–Behnken design was applied to optimize the entrapment efficiency. These phytosomes were further modified with DSPE-PEG (2000)-maleimide and apolipoprotein E and characterized by dynamic light scattering, UV spectrophotometry, octanol/water partition coefficient, differential scanning calorimetry, and Fourier transform infrared spectroscopy. As proof of concept, prototypes of functional food tailored to the elderly were produced. Yogurts were fortified with seaweed extract or phytosomes, and physicochemical properties and proximal composition (pH, acidity, syneresis, moisture, peroxides, proteins, total lipids, sugar content, ash, and mineral composition) were analyzed. The antioxidant and the inhibition capacity of two brain enzymes, cholinesterases (AChE and BuChE), involved in the pathogenesis of Alzheimer’s disease, were also evaluated in the final prototypes. Despite their unappealing sensory characteristics, the results are promising for integrating marine extracts with potential neuroprotective effects into functional foods. Full article

Furan/maleimide dynamic covalent chemistry has been extensively used to fabricate re-workable and self-healing thermosets. Understanding the relationship between crosslinker structure, network dynamics, and material final properties, however, remains a challenge. This study introduces self-healing and shape-memory thermosets derived from furan-functionalized polyketones (PKFU) crosslinked with aromatic bis-maleimides, i.e., 1,1′-(methylenedi-4,1-phenylene)bis-maleimide (BISM1) and bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (BISM2), via a thermally reversible Diels-Alder reaction. Polyketones were chemically modified with furfurylamine through the Paal-Knorr reaction, achieving varying furan grafting ratios. The resulting networks, characterized by ATR-FTIR, ¹H-NMR, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and rheology, demonstrated tunable thermomechanical properties. BISM2-based thermosets exhibited enhanced thermal stability and reversibility over a broad temperature range (20–120 °C), with a shape recovery ratio of up to 89% and complete self-healing at 120 °C within 5 min. These findings highlight the potential of polyketone-based thermosets for applications requiring adaptive thermomechanical properties, efficient self-repair, and sustainability. Full article

Throughout the last 5 years, extensive research has been carried out towards the development of effective treatments for coronavirus disease 2019 (COVID-19). Regardless of the worldwide efforts, only a few drugs have passed clinical trials, and there is still a need to develop therapies, especially for those who are particularly vulnerable to a severe disease course. Maleimide-functionalized liposomes are proposed to serve as a platform for the immobilization, stabilization, and delivery of a short peptide sequence with high affinity towards severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). However, extensive optimizations should be performed in order to achieve features required for a reliable drug candidate, such as homogeneity of physical parameters and their long-term stability. Here, we present a step-by-step development process for maleimide-functionalized liposomes, which—once decorated with the SARS-CoV-2-binding peptide—could inhibit the infection progress of COVID-19. The main emphasis is placed on defining optimal lipid composition and formation conditions of PEGylated liposomes. We propose that the developed nanocarrier technology can be used as a universal platform for the construction of multiple antiviral agents. Full article

The separation and purification of molecular compounds and their functionalized derivatives is a common challenge in organic synthesis. In particular, calix[4]resorcinarenes present a high potential for chemical derivatization at their upper edge by aminomethylation reactions, and these compounds and their derivatives require appropriate analytical methodologies for their analysis, separation, and purification. In this study, C-tetra(propyl)calix[4]resorcinarene was synthesized and functionalized with maleimide groups by optimized aminomethylation reactions, obtaining a mixture of mono-, di-, tri-, and tetrasubstituted compounds. Initial separation by RP-HPLC with a core-shell column showed poorly resolved peaks, indicating a loss of separation efficiency. Therefore, a monolithic C18 column was used, which significantly improved the separation, thanks to its larger pore volume and continuous structure facilitating the diffusion of these bulky molecules, notably improving efficiency. Finally, the six compounds functionalized with maleimide groups were efficiently separated and enriched by RP-SPE by analytical method transfer, and the two peptides of six and the thirteen residues derived from LfcinB (20–25): RRWQWR were synthesized by SPPS-Fmoc/tBu and purified. These were modularly linked by the Michael thiol-maleimide addition reaction obtaining six (peptide)_n-resorcinarene conjugates. The analytical method by RP-HPLC with a monolithic C18 column, the separation and purification by RP-SPE were used transversally in all the steps to obtain compounds with adequate purities and quantities. Finally, the antibacterial activities of the six conjugates were evaluated against E. coli and E. faecalis strains, and it was determined that three aminomethylated compounds and one monosubstituted conjugate showed activity against E. faecalis. Our work established a new modular conjugation strategy between calix[4]resorcinarenes and peptides by thiol-maleimide click chemistry, and a methodology of separation, purification, and enrichment for these products by RP-HPLC and RP-SPE, which permitted us to obtain quantities with purities appropriate for their characterization by NMR, LC-MS and antibacterial activity assays. Full article

Background/Objectives: Photoimmunotherapy (PIT) is an innovative approach for the targeted therapy of cancer. In PIT, photosensitizer dyes are conjugated to tumor-specific antibodies for targeted delivery into cancer cells. Upon irradiation with visible light, the photosensitizer dye is activated and induces cancer-specific cell death. In the present article, we describe the PIT of prostate cancer (PC) as a therapeutic option for the targeted treatment of localized prostate cancer. Methods: We conjugated the silicon phthalocyanine dye WB692-CB2 to recombinant cysteine-modified anti-CD44 and anti-EpCAM antibodies via a maleimide linker and tested the antibody dye conjugates for PIT on PC cells and prostate cancer stem cell (PCSC)-like cells. Results: The anti-CD44 and anti-EpCAM antibody dye conjugates showed specific binding and high cytotoxicity against PC and PCSC-like cells following irradiation with red light. Combined treatment with both conjugates led to enhanced cytotoxic effects. Conclusions: PIT with our dye WB692-CB2 can serve as an effective focal therapy against prostate cancer, preserving the prostate gland and minimizing side effects. It can be employed during radical prostatectomy (RP) to treat residual tumor cells or lymph node metastases in areas where further surgical intervention is not feasible. Utilizing multiple conjugates against antigens expressed on differentiated PC and PCSC-like cells, such as CD44 and EpCAM, could be an effective method to eradicate residual cancer cells in heterogeneous tumors. This approach could reduce the risk of local recurrence after RP and thus increase the therapeutic outcome of PC patients. Full article

The serine/threonine kinase CK2 (formerly known as casein kinase II) plays a crucial role in various CNS disorders and is highly expressed in various types of cancer. Therefore, inhibiting this key kinase could be promising for the treatment of these diseases. The CK2 holoenzyme is formed by the recruitment of two catalytically active CK2α and/or CK2α′ subunits by a regulatory CK2β dimer. Starting with the lead furocarbazole W16 (4) inhibiting the CK2α/CK2β interaction, analogous pyrrolocarbazoles were prepared and tested for their protein–protein interaction inhibition (PPII). The key step of the synthesis was a multicomponent Levy reaction of 2-(indolyl)acetate 6, benzaldehydes 7, and N-substituted maleimides 8. Targeted modifications were performed by the saponification of the tetracyclic ester 9a, followed by the coupling of the resulting acid 10 with diverse amines. The replacement of the O-atom of the lead furocarbazole 4 by an N-atom in pyrrolocarbazoles retained or even increased the inhibition of the CK2α/CK2β interaction. The large benzyloxazolidinyl moiety of 4 could be replaced by smaller N-substituents without the loss of the PPII. The introduction of larger substituents at the 2-position and/or at p-position of the phenyl moiety at the 10-position to increase the surface for the inhibition of the PPI did not enhance the inhibition of the CK2α/CK2β association. The strong inhibition of the CK2α/CK2β association by the histidine derivative (+)-20a (K_i = 6.1 µM) translated into a high inhibition of the kinase activity of the CK2 holoenzyme (CK2α₂β₂, IC₅₀ = 2.5 µM). Thus, 20a represents a novel lead compound inhibiting CK2 via the inhibition of the association of the CK2α and Ck2β subunits. Full article

β-parvalbumin (β-PV) is the primary fish allergen responsible for most allergic reactions in individuals sensitive to fish. To ensure food safety, a sandwich-based magnetic immunoassay was developed using maleimide-functionalized magnetic beads (NH-MBs). Specific anti-β-PV antibodies were immobilized on these MBs, and a screen-printed carbon electrode was employed as the electrochemical transducer. A linear concentration range from 10 to 1000 ng/mL, a limit of detection of 1.8 ng/mL, and a limit of quantification of 7.1 ng/mL were achieved. Nineteen commercial food samples were analyzed to assess the potential of the sensor for routine use in food quality control. Important factors such as protein source and food processing (e.g., boiling, grilling, and frying) and preservation (e.g., in oil, and vacuum) were evaluated. The validated results confer the usefulness of the assay for food quality control. Full article

Homogeneous antibody–drug conjugates (ADCs) exhibit significantly improved pharmacological properties compared to their heterogeneous counterparts. Site-specific conjugation of the payload to the IgG required for homogeneity can be achieved using enzymes. One example is microbial transglutaminase (MTGase), which can selectively perform transamidation on the Q295 residue of human Fc when N297 glycans are removed. As a result, two modifications can be introduced per IgG molecule; however, achieving higher drug-to-antibody ratios (DARs) requires the use of branched linkers. While several such linkers have been reported, little information is available on the relationship between linker structure and ADC properties. To address this gap, we synthesized two branched amino triazide linkers, differing by a PEG₄ fragment inserted after the branching point, which were used to prepare two homogeneous trastuzumab-based DAR 6 ADCs (a “short” and a “long” one). This was achieved by a two-step process consisting of enzymatic linker conjugation followed by bioorthogonal coupling with a cleavable linker bearing monomethyl auristatin E (MMAE). Two other trastuzumab–MMAE conjugates were used as controls: a heterogeneous DAR 6 ADC, made using conventional thiol–maleimide chemistry, and a homogeneous DAR 2 ADC. We found that, while the four conjugates had identical affinity for HER2, their cytotoxicity differed significantly: the “long” homogeneous DAR 6 ADC was just as active as its heterogeneous counterpart, but the “short” DAR 6 ADC was an order of magnitude less potent, inferior even to the DAR 2 conjugate. Our findings indicate that the length of the branched linker critically affects the cytotoxic activity of ADCs, possibly due to steric hindrance influencing the rate of linker cleavage by lysosomal enzymes. Full article