Bioconjugate Chemistry最新文献

Polymer-based delivery vehicles are a promising nonviral alternative for nucleic acid therapeutics; however, current formulations often have low transfection efficiency or if effective, have high toxicity. Herein, we investigate the use of blended polymeric micelles, an ordered assembly of amphiphilic block copolymers in solution, for the delivery of mRNA. Three cationic amphiphiles consisting of a primary amine (C1), dimethylamine (C2), or diethyleneimine (C3) were synthesized. Neutral amphiphiles containing morpholino (M), hydroxy (H), dihydroxy (DH), brush PEG (PB), or two linear PEGs (P5K, P10K) were also created. Seventy-five micelles were formed by blending each cationic and neutral amphiphile at 5 compositions. In the absence of serum, C2 micelles with PEG incorporations above 10% had the highest transfection efficiency; however, C3 formulations were more optimal, having more moderate transfection efficiencies and improved viability. In the presence of serum, C3 formulations with 5 and 10% neutral group incorporations were the most effective, maintaining cell viabilities on par with untreated controls and transfection efficiencies superior to purely cationic micelles. Higher neutral loadings of 20 and 40% reduced transfection efficiency. IL-1β release from macrophages during transfection was also measured as an indicator for potential inflammatory responses. Neutral group loadings of 10% with C1 and C2 significantly reduced cytokine release. In contrast, 10% neutral loadings for C3 micelles slightly increased cytokine release; however, these levels were still below those measured for C2 formulations, indicative of improved biocompatibility of C3 relative to C2. One notable exception was 10% M in C3 micelles, which produced levels on par with Nigericin, a microbial toxin known to include inflammasome activation. Neutral loadings of 40% reduced cytokine release across the formulation space, indicative of improved biocompatibility. Overall, this work demonstrates that changes in formulation chemistry can produce polymeric systems of improved transfection efficiency, without a coinciding increase in toxicity and immunogenicity, to yield more desirable vehicles for nucleic acid delivery.

We present a one-pot approach for orthogonal dual functionalization of mi3 self-assembling protein nanoparticles by combining SpyCatcher003/SpyTag003 isopeptide bond formation with Sortase A-mediated transpeptidation. The nanoparticles were engineered with N-terminal SpyCatcher003 domains and C-terminal LPETGGH motifs, enabling site-specific conjugation of distinct cargo molecules. To overcome expression limitations, an N-terminal vesicle nucleating peptide (VNP6) was incorporated, which enhanced protein yields while maintaining nanocage integrity. Critical to this strategy, the calcium-independent Sortase A variant (SRT7+) was employed to avoid calcium-induced nanoparticle aggregation, enabling orthogonal ligation under physiological conditions. The platform enabled simultaneous conjugation of HER2-targeting affibodies and fluorescent probes in a single reaction, and these dual-functionalized self-assembling protein nanoparticles exhibited specific cellular uptake in HER2-positive cancer cells. This integrated one-pot approach proved scalable and modular for engineering protein-based nanomaterials for targeted therapy and diagnostics.

Protein modifications targeting canonical, hydrophobic amino acid residues remain scarce under neutral, transition metal-free, and biocompatible conditions. Here, we report an electrochemical tryptophan (Trp)-selective bioconjugation that proceeds in a neutral buffer without external oxidants. The method relies on a cooperative dual N-oxyl radical manifold, employing keto-ABNO as the Trp-reactive reagent and 4-oxo-TEMPO as an electron mediator, together with NaBr, which suppresses overoxidation and radical degradation while maintaining low operating potentials. Under the optimized conditions, diverse peptides and proteins are efficiently labeled. Systematic cyclic voltammetry (CV) and UV–visible absorption spectroelectrochemistry (UV/Vis-SEC) suggest a Trp···keto-ABNO preassociation that lowers the oxidation threshold and reveal distinct roles of the two radicals, while Br^– preferentially stabilizes the oxoammonium species rather than mediating redox processes. This neutral-buffer, electrocatalytic platform provides a practical route to Trp-selective labeling under physiologically compatible conditions.

Tissue-clearing techniques have transformed optical imaging of fixed specimens, yet their application to living systems remains limited by toxicity and removal of key tissue components. We recently demonstrated that absorbing molecules such as tartrazine can reversibly render live mouse skin transparent. Subsequently, it was reported that isotonic protein solutions can achieve ex vivo and in vivo cellular clearing. However, discrepancies remain regarding the optimal refractive index (RI) for live-cell clearing and the impact of elevated osmolality on cell viability. Here, using cultured mammalian cells, we systematically examine the dependence of optical contrast on medium RI and the effects of hyperosmolality. We find that, contrary to the recent report of an optimal RI of 1.36 ∼ 1.37 for suspended cells, densely packed adherent cells exhibit a monotonic decrease in phase contrast up to an RI of 1.41 with tartrazine. Moreover, even under highly hyperosmotic conditions (∼1200 mOsm/kg), cultured cells exhibit minimal deformation and negligible loss of viability for up to 30 min in the clearing solution. These results demonstrate that tartrazine enables effective live-cell clearing at RI up to 1.41 while preserving viability under elevated osmolality and motivate future studies to define optimal conditions for in vivo optical clearing.

Ferroptosis, an iron-dependent regulated cell death modality driven by lipid peroxidation (LPO) and mitochondrial dysfunction, represents a promising therapeutic target for tumors, given cancer cells’ elevated iron demand, reactive oxygen species (ROS) levels, and reliance on glutathione peroxidase 4 (GPX4) for redox homeostasis. While single-atom nanozymes (SANs) have emerged as potent catalytic tools for ROS-driven ferroptosis induction, their efficacy is hampered by the abundant glutathione and ROS-scavenging GPX4, which suppress sustained LPO accumulation. To address this bottleneck, we engineer a proof-of-concept Fe-based SAN (Fe-SAN) with well-defined Fe–N₄ active sites and further encapsulate the GPX4 inhibitor Fin56 to construct the Fe-SAN@F nanoplatform. Fe-SAN@F showed dual catalytic activities: robust peroxidase-like activity that converts endogenous hydrogen peroxide into cytotoxic ^•OH to trigger LPO and glutathione oxidase-like activity that depletes intracellular GSH to inactivate GPX4. Meanwhile, the loaded Fin56 exerts synergistic GPX4 inhibition, amplifying the ROS cascade. In vitro and in vivo assays confirm that Fe-SAN@F induces irreversible tumor ferroptosis via the combined effects of LPO accumulation, GSH depletion, and GPX4 inactivation, effectively suppressing tumor proliferation. This work establishes a novel SAN-based catalytic therapy paradigm for remodeling the TME and boosting ferroptosis, providing a rational design strategy for next-generation precision antitumor nanozymes.

New and efficient chemical reactions with broad substrate applicability are needed to expand the diversity of DNA-encoded libraries (DELs), which are becoming established as a powerful technology for hit finding in medicinal chemistry. For reactions to be useful, they must be compatible with the DNA-tags and with the aqueous conditions used in DEL synthesis. One potential approach to address this requirement is the application of surfactant-mediated chemistry, which can lead to improved reaction efficiency. Our recent application of this technology to Buchwald–Hartwig aminations is very effective at coupling (hetero)aryl amines but performed less well for aliphatic substrates. This paper describes the development of an efficient, surfactant-promoted method of effecting on-DNA Buchwald–Hartwig aminations on DNA with aliphatic amines. This was developed through sequential optimization of the base, palladium ligand and the surfactant, for which Span 60 proved optimal. The applicability of the method is demonstrated across a broad substrate scope and its use in the synthesis of DELs is demonstrated by the synthesis of a prototype library.

In development of antibody–drug conjugates (ADCs), cathepsin B-cleavable linkers have been extensively optimized for amine-containing payloads and successfully translated into clinic practice, whereas effective solutions for hydroxyl-containing payloads remain limited. Here, we report a cathepsin B-cleavable VA-PAB-2-HPC^CONH self-immolative linker platform featuring three orthogonal attachment sites that enable modulation of linker–payload hydrophilicity. Using this platform, we designed and synthesized highly water-soluble linker–payload conjugates, incorporating either phenolic hydroxyl payload CPT002 or aliphatic hydroxyl payload DXd, and constructed anti-HER2 and anti-Trop2 ADCs. In addition to excellent plasma stability and efficient enzymatic release, these ADCs showed robust in vitro cytotoxicity. Notably, they achieved in vivo antitumor efficacy and safety on par with the clinical benchmark DS-8201a. Collectively, this work establishes a versatile and generalizable linker strategy that expands the accessible payload space of ADCs and enables efficient, controlled delivery of hydroxyl-containing payloads, highlighting its potential for next-generation ADC development.

Human heavy-chain ferritin (FTn) that can bind to transferrin receptor 1 (TfR1) has emerged as a promising platform for brain tumor drug delivery. However, the broad expression of TfR1 in normal tissues fundamentally limits tumor selectivity and therapeutic precision. Herein, we engineered a dual-receptor-targeting FTn nanoplatform by site-specifically conjugating an epidermal growth factor receptor (EGFR) affibody to FTn using the SpyCatcher/SpyTag system, generating FTn-EGFRAfb nanoparticles. This modular strategy preserves FTn architecture and stability while enabling precise ligand conjugation. Doxorubicin (DOX) was efficiently encapsulated via temperature-controlled loading to obtain DOX@FTn-EGFRAfb with high protein recovery, pH-responsive drug release, and strong stability. In vitro, the nanoparticles showed enhanced uptake and cytotoxicity in TfR1/EGFR double-positive U87 glioma cells. In an orthotopic U87 glioma mouse model, DOX@FTn-EGFRAfb significantly inhibited tumor growth and prolonged survival without obvious systemic toxicity. This work presents a versatile protein-engineering strategy for dual-targeted glioblastoma drug delivery.

Sensitive cytokine quantification is essential for understanding inflammatory disease mechanisms and guiding diagnostic development. Here, we characterize a magnetic bead electrochemical sandwich assay (MBESA) based upon 2.8 μm magnetic Dynabeads for the rapid electrochemical detection of the inflammatory cytokine interleukin-1β (IL-1β), a key mediator of immune signaling. Scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (STEM-EDX) provided high-resolution visualization and quantitative mapping of conjugated MBESA layers. Incorporation of streptavidin-gold nanospheres provided direct, nanoscale evidence of antibody and antigen bioconjugation, revealing binding heterogeneity marked by a triplicate increase in sulfur content. This work demonstrates precise quantification of assay bioconjugation, addressing a critical gap in the structural characterization of bead-based immunoassays. By bridging biomolecule arrangement to assay performance, the MBESA positions itself as a leading electrochemical platform for inflammatory cytokine detection.

Theranostics, an integrated approach combining cancer diagnosis and therapy, has gained increasing attention, particularly in the field of radiotheranostics using radioligands. The cholecystokinin 2 receptor (CCK2R), which is overexpressed in various neuroendocrine tumors (NETs), is considered a promising target for radiotheranostic applications. However, the currently available CCK2R-targeted ligand, DOTA-MGS5, exhibits limited tumor accumulation. Incorporation of an albumin binder (ALB) unit, which is capable of interacting with serum albumin, has been reported to enhance tumor accumulation of radioligands by prolonging their biological half-lives. To establish a more efficient CCK2R-targeted radiotheranostic strategy, we developed a novel CCK2R-targeted ALB-containing radioligand, [¹¹¹In]In/[¹⁷⁷Lu]Lu-MGS5-DA, based on DOTA-MGS5. In biodistribution studies, [¹¹¹In]In-MGS5-DA showed markedly higher tumor accumulation compared with [¹¹¹In]In-DOTA-MGS5. Moreover, single-photon emission computed tomography/computed tomography (SPECT/CT) imaging confirmed that [¹¹¹In]In-MGS5-DA could be used to clearly visualize CCK2R-expressing tumors. In a peptide receptor radionuclide therapy (PRRT) study, [¹⁷⁷Lu]Lu-MGS5-DA led to greater tumor growth inhibition than [¹⁷⁷Lu]Lu-DOTA-MGS5. These findings suggest that [¹¹¹In]In/[¹⁷⁷Lu]Lu-MGS5-DA is a promising radiotheranostic pair for the treatment of CCK2R-expressing cancers.