Heme-Mimetic Photosensitizer with Iron-Targeting and Internalizing Properties for Enhancing PDT Activity and Promoting Infected Diabetic Wound Healing.

The management of multibacterial infections remains clinically challenging in the care and treatment of chronic diabetic wounds. Photodynamic therapy (PDT) offers a promising approach to addressing bacterial infections. However, the limited target specificity and internalization properties of traditional photosensitizers (PSs) toward Gram-negative bacteria pose significant challenges to their antibacterial efficacy. In this study, we designed an iron heme-mimetic PS (MnO2@Fe-TCPP(Zn)) based on the iron dependence of bacteria that can be assimilated by bacteria and retained in different bacteria strains (Escherichia coli, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus) and which shows high PDT antibacterial efficacy. For accelerated wound healing after antibacterial treatment, MnO2@Fe-TCPP(Zn) was loaded into a zwitterionic hydrogel with biocompatibility and antifouling properties to form a nanocomposite antibacterial hydrogel (PSB-MnO2@Fe-TCPP(Zn)). In the multibacterial infectious diabetic mouse wound model, the PSB-MnO2@Fe-TCPP(Zn) hydrogel dressing rapidly promoted skin regeneration by effectively inhibiting bacterial infections, eliminating inflammation, and promoting angiogenesis. This study provides an avenue for developing broad-spectrum antibacterial nanomaterials for combating the antibiotic resistance crisis and promoting the healing of complex bacterially infected wounds.

Glucopeptide Superstructure Hydrogel Promotes Surgical Wound Healing Following Neoadjuvant Radiotherapy by Producing NO and Anticellular Senescence.

Neoadjuvant radiotherapy, a preoperative intervention regimen for reducing the stage of primary tumors and surgical margins, has gained increasing attention in the past decade. However, radiation-induced skin damage during neoadjuvant radiotherapy exacerbates surgical injury, remarkably increasing the risk of refractory wounds and compromising the therapeutic effects. Radiation impedes wound healing by increasing the production of reactive oxygen species and inducing cell apoptosis and senescence. Here, a self-assembling peptide (R-peptide) and hyaluronic-acid (HA)-based and cordycepin-loaded superstructure hydrogel is prepared for surgical incision healing after neoadjuvant radiotherapy. Results show that i) R-peptide coassembles with HA to form biomimetic fiber bundle microstructure, in which R-peptide drives the assembly of single fiber through π-π stacking and other forces and HA, as a single fiber adhesive, facilitates bunching through electrostatic interactions. ii) The biomimetic superstructure contributes to the adhesion and proliferation of cells in the surgical wound. iii) Aldehyde-modified HA provides dynamic covalent binding sites for cordycepin to achieve responsive release, inhibiting radiation-induced cellular senescence. iv) Arginine in the peptides provides antioxidant capacity and a substrate for the endogenous production of nitric oxide to promote wound healing and angiogenesis of surgical wounds after neoadjuvant radiotherapy.

EISA in Tandem with ICD to Form In Situ Nanofiber Vaccine for Enhanced Tumor Radioimmunotherapy.

Radiotherapy (RT) can produce a vaccine effect and remodel a tumor microenvironment (TME) by inducing immunogenic cell death (ICD) and inflammation in tumors. However, RT alone is insufficient to elicit a systemic antitumor immune response owing to limited antigen presentation, immunosuppressive microenvironment, and chronic inflammation within the tumor. Here, a novel strategy is reported for the generation of in situ peptide-based nanovaccines via enzyme-induced self-assembly (EISA) in tandem with ICD. As ICD progresses, the peptide Fbp-GD FD FD pY (Fbp-pY), dephosphorylated by alkaline phosphatase (ALP) forms a fibrous nanostructure around the tumor cells, resulting in the capture and encapsulation of the autologous antigens produced by radiation. Utilizing the adjuvant and controlled-release advantages of self-assembling peptides, this nanofiber vaccine effectively increases antigen accumulation in the lymph nodes and cross-presentation by antigen-presenting cells (APCs). In addition, the inhibition of cyclooxygenase 2 (COX-2) expression by the nanofibers promotes the repolarization of M2-macrophages into M1 and reduces the number of regulatory T cells (Tregs) and myeloid-derived suppressor cells (MDSCs) required for TME remodeling. As a result, the combination of nanovaccines and RT significantly enhances the therapeutic effect on 4T1 tumors compared with RT alone, suggesting a promising treatment strategy for tumor radioimmunotherapy.

Achieving higher hierarchical structures by cooperative assembly of tripeptides with reverse sequences.

Hierarchical self-assembly based on peptides in nature is a multi-component interaction process, providing a broad platform for various bionanotechnological applications. However, the study of controlling the hierarchical structure transformation via the cooperation rules of different sequences is still rarely reported. Herein, we report a novel strategy of achieving higher hierarchical structures through cooperative self-assembly of hydrophobic tripeptides with reverse sequences. We unexpectedly found that Nap-FVY and its reverse sequence Nap-YVF self-assembled into nanospheres, respectively, while their mixture formed nanofibers, obviously exhibiting a low-to-high hierarchical structure transformation. Further, this phenomenon was demonstrated by the other two collocations. The cooperation of Nap-VYF and Nap-FYV afforded the transformation from nanofibers to twisted nanoribbons, and the cooperation of Nap-VFY and Nap-YFV realized the transformation from nanoribbons to nanotubes. The reason may be that the cooperative systems in the anti-parallel ß-sheet conformation created more hydrogen bond interactions and in-register π-π stacking, promoting a more compact molecular arrangement. This work provides a handy approach for controlled hierarchical assembly and the development of various functional bionanomaterials.

[Removal of NO and Hg0 in flue gas using alkaline absorption enhanced by non-thermal plasma].

Non-thermal plasma (NTP) induced by positive corona discharge was utilized to oxidize NO and Hg0 to more water-soluble NO2 and Hg2+ under the conditions of simulated flue gas. The effects of discharge voltage and inlet SO2 and NO concentrations on NO and Hg0 oxidation and their removals by alkaline absorption were investigated. The results show that the oxidation and removal of NO and Hg0 are enhanced with the increase of discharge voltage. The concentrations of NO and NO2 at the outlet of absorption tower are 0 and 69 mg/m3 with an inlet NO concentration of 134 mg/m3 and a discharge voltage of 12. 8 kV while the outlet concentrations of Hg0 and Hg2+ are 22 microg/m3 and 11 microg/m3 with an inlet Hg0 concentration of 110 microg/m3 and a discharge voltage of 13.1 kV. The presence of SO2 slightly improves the oxidation and removal of Hg0 while it has almost no effect on NO oxidation and its removal. The oxidation and removal of Hg0 are significantly inhibited with the increase of inlet NO concentration. In the coexistence of 800 mg/m3 SO2, 134 mg/m3 NO and 110 microg/m3 Hg0, the removal efficiencies are 57% for NO and 31% for Hg0 with an energy input of 77 J/L.

[Effects of gas compositions on the oxidation of gas phase elementary mercury by non-thermal plasma].

The effects of flue gas compositions such as NO, SO2, CO, H2O on elementary mercury oxidation by non-thermal plasma induced by positive streamer discharge were experimentally investigated by using a link tooth wheel-cylinder reactor. The results showed that the oxidation of elementary mercury decreased in the presence of CO2 and NO, which was attributed to the reduction of number of the active radicals reacted with elementary mercury. Adding 670 mg/m3 NO, only 37% elementary mercury was oxidized when the voltage was 9.5 kV. And CO was produced because of the reaction between CO2 and active radicals. The presence of SO2 resulted in an increase of elementary mercury oxidation, and white HgSO4 and Hg2SO4 were formed, little elementary mercury was detected at the outlet of the reactor when the voltage was 10 kV. Similarly, H2O and HCI promoted the oxidation of elementary mercury, which may be due to the formation of oxidative *OH and the presence of Cl- ions. The total mercury concentration dramatically decreased after the discharge reactor because the charging mercury was collected.