Polydopamine (PDA) has been widely used in biomedical applications including imaging contrast agents, antioxidants, UV protection, and photothermal therapy due to its biocompatibility, metal-ion chelation, free-radical scavenging, and wideband absorption, but its low photothermal efficiency still needs to be improved. In this study, we chelated near-infrared (NIR) sensitive carbon quantum dots on the surface of polydopamine (PDA-PEI@N,S-CQDs) to increase its near-infrared absorption. Surprisingly, although only 4% (w/w) of carbon quantum dots was conjugated on the PDA surface, it still increased the photothermal efficiency by 30%. Moreover, PDA-PEI@N,S-CQDs could also be used as the drug carrier for loading 60% (w/w) of the DOX and achieved stimuli-responsive drug release under lysosomal pH (pH 5.0) and 808 nm laser illumination. For in vitro therapeutic experiment, PDA-PEI@N,S-CQDs showed the remarkable therapeutic performance under 808 nm laser irradiation for killing 90% of cancer cells compared with 50% by pure PDA nanoparticles, and the efficacy was even higher after loading DOX owing to the synergistic effect by photothermal therapy and chemotherapy. This intelligent and effective therapeutic nanosystem based on PDA-PEI@N,S-CQDs showed enhanced photothermal behavior after chelating carbon dots and promoted the future development of a nanoplatform for stimuli-responsive photothermal/chemo therapy.

Ultrasmall nanoparticles (USNPs) with sizes below 10 nm have shown great potentials in medical applications owing to their outstanding physical, chemical, optical, and biological properties. However, they suffer from a rapid renal clearance and biodegradation rate in the biological environment due to the small size. Liposomes are one of the most promising delivery nanocarriers for loading USNPs because of their excellent biocompatibility and lipid bilayer structure. Encapsulation of USNPs into liposomes in an efficient and controllable manner remains a challenge. In this study, we achieved a high loading of graphene quantum dots (GQDs, ∼4 nm), a typical USNP, into the aqueous core of liposomes (45.68 ± 1.44%), which was controllable by the pressure. The GQDs-loaded liposomes (GQDs-LPs) exhibited a very good aqueous stability for over a month. Furthermore, indocyanine green (ICG), an efficient near-infrared (NIR) photothermal agent, was introduced in the GQDs-LP system that could convert NIR laser energy into thermal energy and break down the liposomes, causing the release of GQDs in 6 min. Moreover, this NIR light-controlled release system (GQDs-ICG-LPs) also exhibited a good photothermal therapeutic performance in vitro, and 75% of cancer cells were killed at a concentration of 200 μg/mL. Overall, the successful development of the NIR light-controlled release system has laid a solid foundation for the future biomedical application of USNPs-loaded liposomes.

Small interfering RNA (siRNA) for gene therapy has attracted great attention. However, due to easy degradation and inaccessibility to the cells, the gene silencing efficiency is not always satisfactory. To overcome this hurdle, developing an excellent nanocarrier to deliver siRNA into cancer cells is crucial. Fluorescent mesoporous silica nanoparticles are considered to be a superb nanocarrier for siRNA delivery systems because of its negligible toxicity and good biocompatibility. Herein, we developed an efficient fluorescent ultrasmall mesoporous silica nanocarrier for siRNA loading and delivery. The ultrasmall nanocarriers with polyethyleni-mine coating have a uniform size of about 10 nm. We find that the amino groups on polyethylenimine can protect siRNA from being degraded. Based on the fluorescence observation, we show that polyethylenimine-coated mesoporous silica nanocarrier loaded with siRNA can be uptake by 293T cells. Importantly, we also prove that siRNA can be delivered into 293T cells by our nanocarrier and subsequently inhibit the expression of related genes. The study provides insights into the development of nonviral fluorescence nanocarriers for siRNA delivery, which have important implications for targeted cancer therapy.

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The production of paper‐based food packaging materials is of vital importance as the release of microplastics into aqueous environment and food chain has aroused significant public concern. In this study, antibacterial pulp board was demonstrated by co‐spraying chitosan (CS) and ε‐polylysine (ε‐PL) on wet sheet and dried to form fibrous pulp board (ε‐PL‐CS). ε‐PL functionalization showed great antibacterial performance while its hydrophilicity limited its further application for food packaging. Interestingly, ε‐PL‐CS pulp board not only demonstrated excellent antibacterial performance (99.99% against both bacteria Staphylococcus aureus and Escherichia coli), but also maintained high hydrophobicity (ca. 135°) and water resistance due to the positive charge of ε‐PL and CS as well as penetration of CS into pulp board. In addition, CS functionalization significantly improved the mechanical strength of the pulp board by around 100% (20 MPa). More importantly, the ε‐PL‐CS pulp board could successfully prevent bacteria growth within 15 days at room temperature due to their high hydrophobicity and smooth surface, indicating the long‐term stability as packaging materials. Satisfactory strawberry storage stability of ε‐PL‐CS cardboard lunch box provided great application promise for the development of antimicrobial packaging materials.