ACS Central Science最新文献

Mitochondrial targeting has emerged as an attractive method for antitumor treatment. However, most of the mitochondria targeted drugs focused on inhibiting tumor cells, while their potential for activation of immune responses in the tumor microenvironment has rarely been described. In this study, we report a photosensitive iridium complex MitoIrL2, which enabled the simultaneous mitochondrial modulation of macrophages and tumor cells to achieve synergistic antitumor immunity. The adjustment of the mitochondrial respiratory chain, HIF-1α, and the NF-κB pathway in macrophages drove the metabolic reprogramming from oxidative phosphorylation (OXPHOS) to glycolysis, converting protumor M2 into the antitumor M1 phenotype. Downregulated expression of immunosuppressive checkpoint SIRPα has also been observed on macrophages. Meanwhile, the mitochondrial targeting MitoIrL2 enhanced the immunogenic cell death of tumor cells and reversed the immunosuppressive tumor microenvironment, which activated the systemic immune response and established long-term immune memory in vivo. This work illustrates a promising strategy to simultaneously regulate macrophages toward the antitumor phenotype and enhance immunogenic cell death in tumor cells for synergistic antitumor immunotherapy.

Thioesters, rather than oxo-esters, can be tolerated and processed during translation to incorporate unnatural monomers.

Macrocyclic peptides make up a unique class of modalities known for their high affinity, specificity, and ability to modulate protein-protein interactions, including receptor activation. Messenger RNA display, including the Random Nonstandard Peptides Integrated Discovery (RaPID) system, stands out in identifying target-specific macrocyclic peptides, producing potent binders with low to subnanomolar dissociation constants against diverse targets. It has often been discussed that this success is partly attributed to the vast library of over a trillion different peptide sequences expressed from the corresponding mRNA sequences. However, the impact of library scales on the identification of various binders has not been experimentally validated. Here, we report the RaPID selections against an ectodomain of a receptor tyrosine kinase MET using peptide libraries ranging from 10⁶ to 10¹⁴ unique members of mRNAs. We thoroughly analyzed the outcomes, including the binding kinetic properties, of the enriched peptide families. This study provides valuable guidelines for designing libraries with various numbers of sequences and selection conditions to enrich macrocyclic peptides with the desired characteristics.

Macrocyclic peptides make up a unique class of modalities known for their high affinity, specificity, and ability to modulate protein–protein interactions, including receptor activation. Messenger RNA display, including the Random Nonstandard Peptides Integrated Discovery (RaPID) system, stands out in identifying target-specific macrocyclic peptides, producing potent binders with low to subnanomolar dissociation constants against diverse targets. It has often been discussed that this success is partly attributed to the vast library of over a trillion different peptide sequences expressed from the corresponding mRNA sequences. However, the impact of library scales on the identification of various binders has not been experimentally validated. Here, we report the RaPID selections against an ectodomain of a receptor tyrosine kinase MET using peptide libraries ranging from 10⁶ to 10¹⁴ unique members of mRNAs. We thoroughly analyzed the outcomes, including the binding kinetic properties, of the enriched peptide families. This study provides valuable guidelines for designing libraries with various numbers of sequences and selection conditions to enrich macrocyclic peptides with the desired characteristics.

The initial sampling of the sequence space determines the evolution of the families by the RaPID selection pressure for slow dissociation rates.

[This corrects the article DOI: 10.1021/acscentsci.4c01822.].

Triplet-triplet annihilation photon upconversion (TTA-UC) systems hold great promise for applications in energy, 3D printing, and photopharmacology. However, their optimization remains challenging due to the need for precise tuning of sensitizer and annihilator concentrations under oxygen-free conditions. This study presents an automated, high-throughput platform for the discovery and optimization of TTA-UC systems. Capable of performing 100 concentration scans in just two hours, the platform generates comprehensive concentration maps of critical parameters, including quantum yield, triplet energy transfer efficiency, and threshold intensity. Using this approach, we identify key loss mechanisms in both the established and novel TTA-UC systems. At high porphyrin-based sensitizer concentrations, upconversion quantum yield losses are attributed to sensitizer triplet self-quenching via aggregation and sensitizer triplet-triplet annihilation (sensitizer-TTA). Additionally, reverse triplet energy transfer (RTET) at elevated sensitizer levels increases the upconversion losses and excitation thresholds. Testing novel sensitizer-annihilator pairs confirms these loss mechanisms, highlighting opportunities for molecular design improvements. This automated platform offers a powerful tool for advancing TTA-UC research and other photochemical studies requiring low oxygen levels, intense laser excitation, and minimal material use.

Triplet–triplet annihilation photon upconversion (TTA-UC) systems hold great promise for applications in energy, 3D printing, and photopharmacology. However, their optimization remains challenging due to the need for precise tuning of sensitizer and annihilator concentrations under oxygen-free conditions. This study presents an automated, high-throughput platform for the discovery and optimization of TTA-UC systems. Capable of performing 100 concentration scans in just two hours, the platform generates comprehensive concentration maps of critical parameters, including quantum yield, triplet energy transfer efficiency, and threshold intensity. Using this approach, we identify key loss mechanisms in both the established and novel TTA-UC systems. At high porphyrin-based sensitizer concentrations, upconversion quantum yield losses are attributed to sensitizer triplet self-quenching via aggregation and sensitizer triplet–triplet annihilation (sensitizer-TTA). Additionally, reverse triplet energy transfer (RTET) at elevated sensitizer levels increases the upconversion losses and excitation thresholds. Testing novel sensitizer–annihilator pairs confirms these loss mechanisms, highlighting opportunities for molecular design improvements. This automated platform offers a powerful tool for advancing TTA-UC research and other photochemical studies requiring low oxygen levels, intense laser excitation, and minimal material use.

A high-throughput concentration screening method built from commercial components for determining upconversion quantum yield and excitation threshold in sensitized triplet−triplet annihilation systems.

The relationship between macroscopic stress relaxation and molecular-level chain exchange in triblock copolymer micelles has been explored using rheology and time-resolved small-angle neutron scattering (TR-SANS), marking the first measurements of chain exchange in concentrated triblock networks. It has long been assumed in models of transient or thermoreversible networks that the time scales for these two processes are equal. Experimentally, we find that stress relaxation occurs many orders-of-magnitude faster than chain exchange. This difference is quantitatively explained by modest dispersity in the core block that results in a slight asymmetry within any given nominally symmetric triblock. For stress relaxation to occur, only the shorter chain must pull out, while chain exchange is slowed due to the requirement of the eventual pullout of the longer block. The pullout time is extremely sensitive to the length of the core block. This mechanism is supported by measurements with an intentionally asymmetric triblock copolymer, which displays an even larger difference between the stress relaxation and chain exchange rates. These results establish a quantitative molecular-level picture of the chain dynamics associated with stress relaxation in triblock copolymer networks.

A quantitative relationship is established between the flow time of a BAB triblock copolymer network, from rheology, and the time for a single B end block to escape from its micellar cross-link, determined by neutron scattering.