ACS Central Science最新文献

Electron microscopy in its various forms is one of the most powerful imaging and structural elucidation methods in nanotechnology where sample information is generally limited by random chemical and structural damage. Here we show how a well-selected chemical probe can be used to transform indiscriminate chemical damage into clean chemical processes that can be used to characterize some aspects of the interactions between high-energy electron beams and soft organic matter. Crystals of a Dewar benzene exposed to a 300 keV electron beam facilitate a clean valence-bond isomerization radical-cation chain reaction where the number of chemical events per incident electron is amplified by a factor of up to ca. 90,000.

A crystalline Dewar benzene undergoes up to 90,000 reactions per incident electron, rapidly losing diffraction and massively amplifying the effects of ionization in microelectron diffraction.

Electron microscopy in its various forms is one of the most powerful imaging and structural elucidation methods in nanotechnology where sample information is generally limited by random chemical and structural damage. Here we show how a well-selected chemical probe can be used to transform indiscriminate chemical damage into clean chemical processes that can be used to characterize some aspects of the interactions between high-energy electron beams and soft organic matter. Crystals of a Dewar benzene exposed to a 300 keV electron beam facilitate a clean valence-bond isomerization radical-cation chain reaction where the number of chemical events per incident electron is amplified by a factor of up to ca. 90,000.

Amphiphilic lipid oligonucleotide conjugates are powerful molecular-engineering materials that have been used for delivery of therapeutic oligonucleotides. However, conventional lipid oligonucleotide conjugates suffer from poor selectivity to target cells due to the nonspecific interaction between lipid tails and cell membranes. Herein, a reconfigurable DNA nanotweezer consisting of a c-Met aptamer and bischolesterol-modified antisense oligonucleotide was designed for c-Met-targeted delivery of therapeutic antisense oligonucleotides. The c-Met aptamer is used to keep the DNA nanotweezer in a “closed” state, which enables the hydrophobic interaction within bischolesterol moieties. As a result, the amphiphilic DNA nanotweezer shows only a weak interaction with the cell membrane. Upon the release of the c-Met aptamer, the DNA nanotweezer converts to an “open” state, which facilitates the insertion of a cholesterol moiety into the cell membrane. Thus, the reconfigurable DNA nanotweezer enables the selective membrane anchoring of the DNA nanotweezer in cancerous cells that highly expressed c-Met protein. Moreover, this amphiphilic DNA nanotweezer shows enhanced accumulation at the tumor site and the inhibition of tumor growth. Taking advantage of the stimuli-responsive membrane anchoring capability, this reconfigurable DNA nanotweezer could be further explored as a smart multifunctional platform for cancer therapy.

c-Met protein-induced conformational transition of the amphiphilic DNA nanotweezer from “closed” to “open” state enables the tunable membrane anchoring capability for enhanced targeted delivery.

Over 90% of cancer patients succumb to metastasis, yet conventional frontline therapy struggles to halt the progression of metastatic tumors. Targeted radionuclide therapy, which delivers radiation precisely to tumor sites, shows promise for treating metastasis. The rational design of a prodrug activation platform using radionuclides would be an ideal approach to synergize chemotherapy with targeted radionuclide therapy, yet it has not been established. Here, we present targeted radionuclide therapy-induced cleavage chemistry that enables the controlled release of oxaliplatin and its axis ligands from oxaliplatin(IV) complexes in living systems. Of note, this strategy demonstrates feasibility over clinically relevant β-emitting radionuclides and exhibits dose dependence. These advantages were taken into account, and a Lutetium-177-activatable platinum(IV) based prodrug system was designed that could achieve localized activation at the tumor site with high efficiency, thereby suppressing subcutaneous and metastatic 4T1 tumors. In summary, our approach highlights the potential of radionuclides as reaction switches, bridging the gap between the radiotherapy-induced reaction and internal radiation. It may provide a new perspective for future combination therapy.

A targeted radionuclide therapy-induced cleavage strategy is designed for in vivo release of oxaliplatin and axial ligands from Pt(IV) compounds, offering a potential approach for treating metastasis.

Over 90% of cancer patients succumb to metastasis, yet conventional frontline therapy struggles to halt the progression of metastatic tumors. Targeted radionuclide therapy, which delivers radiation precisely to tumor sites, shows promise for treating metastasis. The rational design of a prodrug activation platform using radionuclides would be an ideal approach to synergize chemotherapy with targeted radionuclide therapy, yet it has not been established. Here, we present targeted radionuclide therapy-induced cleavage chemistry that enables the controlled release of oxaliplatin and its axis ligands from oxaliplatin(IV) complexes in living systems. Of note, this strategy demonstrates feasibility over clinically relevant β-emitting radionuclides and exhibits dose dependence. These advantages were taken into account, and a Lutetium-177-activatable platinum(IV) based prodrug system was designed that could achieve localized activation at the tumor site with high efficiency, thereby suppressing subcutaneous and metastatic 4T1 tumors. In summary, our approach highlights the potential of radionuclides as reaction switches, bridging the gap between the radiotherapy-induced reaction and internal radiation. It may provide a new perspective for future combination therapy.

Amphiphilic lipid oligonucleotide conjugates are powerful molecular-engineering materials that have been used for delivery of therapeutic oligonucleotides. However, conventional lipid oligonucleotide conjugates suffer from poor selectivity to target cells due to the nonspecific interaction between lipid tails and cell membranes. Herein, a reconfigurable DNA nanotweezer consisting of a c-Met aptamer and bischolesterol-modified antisense oligonucleotide was designed for c-Met-targeted delivery of therapeutic antisense oligonucleotides. The c-Met aptamer is used to keep the DNA nanotweezer in a "closed" state, which enables the hydrophobic interaction within bischolesterol moieties. As a result, the amphiphilic DNA nanotweezer shows only a weak interaction with the cell membrane. Upon the release of the c-Met aptamer, the DNA nanotweezer converts to an "open" state, which facilitates the insertion of a cholesterol moiety into the cell membrane. Thus, the reconfigurable DNA nanotweezer enables the selective membrane anchoring of the DNA nanotweezer in cancerous cells that highly expressed c-Met protein. Moreover, this amphiphilic DNA nanotweezer shows enhanced accumulation at the tumor site and the inhibition of tumor growth. Taking advantage of the stimuli-responsive membrane anchoring capability, this reconfigurable DNA nanotweezer could be further explored as a smart multifunctional platform for cancer therapy.

Electrochemical conversion of CO₂ to hydrocarbons is a promising approach to carbon neutrality and energy storage. The formation of reaction intermediates involves crucial steps of proton transfer, making it essential to understand the role of protons in the electrochemical process to control the product selectivity and elucidate the underlying catalytic reaction mechanism of the CO₂ electrochemical reduction (CO₂RR). In this work, we proposed a strategy to regulate product selectivities by tuning local proton transport rates through a surface resin layer over cuprous oxides. We systematically studied the influence of proton transfer rates on product selectivities by regulating the polymerization degree of resorcinol-formaldehyde resin (RF). The production of C₂ compounds and CH₄ could be switched through an RF coating with the maximum CH₄ Faradaic efficiency of 51% achieved at current densities close to the amperage level. Both experimental and theoretical calculation results suggest that the resin layer can subtly alter proton transfer rates during the electrochemical process, thereby influencing the hydrogen coverage on catalytic sites and ultimately guiding the overall electrochemical performance toward product selectivity.

Proton transfer rates are regulated through a surface resin layer to efficiently tune different product selectivities over copper catalysts during electrochemical CO₂ reduction.

Electrochemical conversion of CO₂ to hydrocarbons is a promising approach to carbon neutrality and energy storage. The formation of reaction intermediates involves crucial steps of proton transfer, making it essential to understand the role of protons in the electrochemical process to control the product selectivity and elucidate the underlying catalytic reaction mechanism of the CO₂ electrochemical reduction (CO₂RR). In this work, we proposed a strategy to regulate product selectivities by tuning local proton transport rates through a surface resin layer over cuprous oxides. We systematically studied the influence of proton transfer rates on product selectivities by regulating the polymerization degree of resorcinol-formaldehyde resin (RF). The production of C₂ compounds and CH₄ could be switched through an RF coating with the maximum CH₄ Faradaic efficiency of 51% achieved at current densities close to the amperage level. Both experimental and theoretical calculation results suggest that the resin layer can subtly alter proton transfer rates during the electrochemical process, thereby influencing the hydrogen coverage on catalytic sites and ultimately guiding the overall electrochemical performance toward product selectivity.

For non-π-conjugated [SO₄] units, it is challenging to generate sufficient birefringence, owing to the high symmetry of the regular tetrahedron. Unlike the traditional trial-and-error approach, we propose a new paradigm for birefringence engineering to tune the optical properties based on [SO₄] units. Through the strategy of ligand substitution, we can predict its effect on the band gap and anisotropy. Theoretical evaluations reveal generalized results that the anisotropic electron distribution of new functional groups induced by the suitable ligand substitution contributes to the band gap and birefringence. To further validate the correctness of the paradigm, we experimentally synthesized and characterized nine novel compounds with selected functional modules. By the new paradigm of ligand substitution, they can reach up to 4–6 times the birefringence of the corresponding sulfate and maintain the wide bandgap. Through rational design, (CN₄H₇)SO₃NH₂ exhibits about 35 times the birefringence of Li₂SO₄, which is a significant order of magnitude improvement and verifies the superiority of our proposed paradigm. This work provides a new paradigm for the modification to the non-π-conjugated group and will guide and accelerate the exploration of novel birefringent crystals in the short-wavelength region.

The new paradigm of ligand substitution focusing on [SO₄] units is proposed and utilized to fine-tune the optical anisotropy, which guides the discovery of novel materials with great birefringence.

For non-π-conjugated [SO₄] units, it is challenging to generate sufficient birefringence, owing to the high symmetry of the regular tetrahedron. Unlike the traditional trial-and-error approach, we propose a new paradigm for birefringence engineering to tune the optical properties based on [SO₄] units. Through the strategy of ligand substitution, we can predict its effect on the band gap and anisotropy. Theoretical evaluations reveal generalized results that the anisotropic electron distribution of new functional groups induced by the suitable ligand substitution contributes to the band gap and birefringence. To further validate the correctness of the paradigm, we experimentally synthesized and characterized nine novel compounds with selected functional modules. By the new paradigm of ligand substitution, they can reach up to 4-6 times the birefringence of the corresponding sulfate and maintain the wide bandgap. Through rational design, (CN₄H₇)SO₃NH₂ exhibits about 35 times the birefringence of Li₂SO₄, which is a significant order of magnitude improvement and verifies the superiority of our proposed paradigm. This work provides a new paradigm for the modification to the non-π-conjugated group and will guide and accelerate the exploration of novel birefringent crystals in the short-wavelength region.