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Drug-loading hydrogels are promising candidates in the bioengineering research field; nevertheless, hydrophobic drug loading into a hydrophilic carrier system remains unsolved and is full of challenges. In this work, following the potential dual interactions between peptides and aromatic drugs, we developed a potent hybrid hydrogel formation method, namely, "peptide-/drug-directed selfassembly". The hybrid hydrogels were synthesized using polyethylene glycol (PEG)-based Fmoc-FF peptide hybrid polyurethane, in which curcumin could be encapsulated through self-assembly with Fmoc-FF peptide via π−π stacking. On the basis of this, curcumin loading capacity could be improved to as high as 3.3 wt % with sustained release. In addition, the curcumin loading enhanced the hydrogel mechanical properties from 4 kPa to over 10 kPa, similar to that of natural soft tissues. Furthermore, the hydrogels were injectable with self-healing properties since the Fmoc-FF peptide/ curcumin coassembly was noncovalent and reversible. Spectroscopy results confirmed the existence of the coassembly of Fmoc-FF peptide/curcumin. Further in vivo experiments effectively demonstrated that the hydrogels could improve the cutaneous wound healing in a full-thickness skin defected model. This peptide-/drug-directed self-assembly of hybrid polyurethane hydrogel could be used as a promising platform for tissue-engineering scaffold and biomedical application.

In recent years, photodynamic therapy (PDT) has drawn much attention as a noninvasive and safe cancer therapy method due to its fine controllability, good selectivity, low systemic toxicity, and minimal drug resistance in contrast to the conventional methods (for example, chemotherapy, radiotherapy, and surgery). However, some drawbacks still remain for the current organic photosensitizers such as low singlet oxygen (1O2) quantum yield, poor photostability, inability of absorption in the near-infrared (NIR) region, short excitation wavelength, and limited action radius of singlet oxygen, which will strongly limit the PDT treatment efficiency. As a consequence, the development of efficient photosensitizers with high singlet oxygen quantum yield, strong fluorescent emission in the aggregated state, excellent photostability, NIR excitation wavelength ranging in the biological transparency window, and highly specific targeting to mitochondria is still in great demand for the enhancement of PDT treatment efficiency. In this study, two new two-photon AIEgens TPPM and TTPM based on a rigid D−π–A skeleton have been designed and synthesized. Both AIEgens TPPM and TTPM show strong aggregation-induced emission (AIE) with the emission enhancement up to 290-folds, large two-photon absorption with the two-photon absorption cross section up to 477 MG, and highly specific targeting to mitochondria in living cells with good biocompatibility. They can serve as two-photon bioprobes for the cell and deep tissue bioimaging with a penetration depth up to 150 μm. Furthermore, high 1O2 generation efficiency with high 1O2 quantum yield under white light irradiation has been found for both TPPM and TTPM and high PDT efficiency to HeLa cells under white light irradiation has also been proven. To the best of our knowledge, AIEgens in this work constitute one of the strongest emission enhancements and one of the highest 1O2 generation efficiencies in the reported organic AIEgens so far. The great AIE feature, large two-photon absorption, high specificity to mitochondria in living cells, and high PDT efficiency to living cells as well as excellent photostability and biocompatibility of these novel AIEgens TPPM and TTPM reveal great potential in clinical applications of two-photon cell and tissue bioimaging and image-guided and mitochondria-targeted photodynamic cancer therapy.

Recently, rapid acquisition of antibiotic resistance, increased prevalence of antibiotic-resistant bacterial infections, and slow healing of infected wound have led to vast difficulties in developing innovative antimicrobial agents to obliterate pathogenic bacteria and simultaneously accelerate wound healing. To effectively solve this problem, we designed light-responsive multifunctional nanoparticles with conjugation of quaternary ammonium chitosan and photosensitizer chlorin e6 (Ce6) to merge chemical and photodynamic therapy to efficient antibacteria. The Mg/(−)-epigallocatechin-3-gallate (EGCG) complex rapidly responded to light irradiation under 660 nm with release of magnesium ions, which effectively accelerated wound healing without toxicity to mammalian cells. Notably, positively charged nanoparticles could efficiently adhere to the bacterial surface, and reactive oxygen species (ROS) produced under laser irradiation destroyed the membrane structure of the bacteria, which is irreversible, ultimately leading to bacteria death. Thus, multifunctional nanoparticles with a combination of chemical and photodynamic antimicrobial therapy would offer guidance to rational predicted and designed new effective antimicrobial nanomaterials. Most importantly, it may represent a promising class of antimicrobial strategy for potential clinical translation.

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