The development of effective antibacterial surfaces to prevent the attachment of pathogenic bacteria and subsequent bacterial colonization and biofilm formation is critically important for medical devices and public hygiene products. In the work reported herein, a smart antibacterial hybrid film based on tannic acid/Fe3+ ion (TA/Fe) complex and poly­(N-isopropylacrylamide) (PNIPAAm) is deposited on diverse substrates. This surface is shown to have bacteria-killing and bacteria-releasing properties based on, respectively, near-infrared photothermal activation and subsequent cooling. The TA/Fe complex has three roles in this system: (i) as a universal adhesive “anchor” for surface modification, (ii) as a high-efficiency photothermal agent for ablation of attached bacteria (including multidrug resistant bacteria), and (iii) as a robust linker for immobilization of NH2-terminated PNIPAAm via either Michael addition or Schiff base formation. Moreover, because of the thermoresponsive properties of the immobilized PNIPAAm, almost all of the killed bacteria and other debris can be removed from the surface simply by lowering the temperature. It is shown that this hybrid film can maintain good antibacterial performance after being used for multiple “kill-and-release” cycles and can be applied to various substrates regardless of surface chemistry or topography, thus providing a broadly applicable, simple, and reliable solution to the problems associated with surface-attached bacteria in various healthcare applications.

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Stimuli-responsive biointerfaces can serve as dynamic tools for modulation of biointerfacial interactions. Considering the complexity of biological environments, surfaces with multistimulus responsive switchable bioactivity are of great interest. In the work reported herein, a multistimulus responsive biointerface with on–off switchable bioadhesion (protein adsorption, bacterial adhesion, and cell adhesion) and surface functions in response to change in temperature, pH, or sugar content is developed. This surface is based on a silicon modified with a copolymer containing a thermoresponsive component (poly­(N-isopropylacrylamide)) and a component, phenylboronic acid, that can form pH-responsive and sugar-responsive dynamic boronate ester bonds with diol-containing molecules. It is shown that biointeractions including protein adsorption and release, bacteria and cell attachment and detachment on this surface can be regulated by changing temperature, pH, and sugar content of the medium, either individually or all three simultaneously. Furthermore, this surface can switch between two different functions, namely between killing and releasing bacteria, by introduction of a diol-containing biocidal compound. Compared to switchable surfaces that are responsive to only one stimulus, our multistimulus responsive surface is better adapted to respond to the multifunctional complexities of the biological environment and thus has potential for use in numerous biomedical and biotechnology applications.

To tackle the problems caused by bacterial biofilms, herein, this study reports an antimicrobial hybrid amphiphile (aHA) via dynamic covalent bonds for eradicating staphylococcal biofilms. aHA is synthesized via iminoboronate ester formation between DETA NONOate (nitric oxide donor), 3 4‐dihydroxybenaldehyde, and phenylboronic acid‐modified ciprofloxacin (Cip). aHA can self‐assemble in aqueous solution with an ultra‐small critical aggregation concentration of 3.80 × 10–5 mm and high drug loading content of 73.8%. The iminoboronate ester is sensitive to the acidic and oxidative biofilm microenvironment, liberating nitric oxide and Cip that can synergistically eradicate bacterial biofilms. To this end, aHA assemblies efficiently eradicate staphylococcal infections and ameliorate inflammation in the murine peritoneal and subcutaneous infection models without any notable side effects on normal tissues. Collectively, the aHA assemblies may provide a facile and efficient alternative to the current development of anti‐biofilm therapies.

Biofilms formed from the pathogenic bacteria that attach to the surfaces of biomedical devices and implantable materials result in various persistent and chronic bacterial infections, posing serious threats to human health. Compared to the elimination of matured biofilms, prevention of the formation of biofilms is expected to be a more effective way for the treatment of biofilm-associated infections. Herein, we develop a facile method for endowing diverse substrates with long-term antibiofilm property by deposition of a hybrid film composed of tannic acid/Cu ion (TA/Cu) complex and poly­(ethylene glycol) (PEG). In this system, the TA/Cu complex acts as a multifunctional building block with three different roles: (i) as a versatile “glue” with universal adherent property for substrate modification, (ii) as a photothermal biocidal agent for bacterial elimination under irradiation of near-infrared (NIR) laser, and (iii) as a potent linker for immobilization of PEG with inherent antifouling property to inhibit adhesion and accumulation of bacteria. The resulted hybrid film shows negligible cytotoxicity and good histocompatibility and could prevent biofilm formation for at least 15 days in vitro and suppress bacterial infection in vivo, showing great potential for practical applications to solve the biofilm-associated problems of biomedical materials and devices.

A universal platform for the efficient intracellular delivery of biomacromolecules with minimal trauma to the cells is highly desirable for biological research and clinical applications. Moreover, such a platform should include the ability to harvest the “engineered” cells, for particular in vitro or ex vivo conditions. Herein, a broadly applicable platform is presented with integrated multifunctions based on silicon nanowire arrays (SiNWAs) modified with a sugar‐responsive polymer containing phenylboronic acid (PBA) groups. Due to the synergistic effects of the specific recognition of PBA groups by sialic acid and “nanoenhancement” by the SiNWAs, this system shows a high capture capacity for both surface adherent and suspension cells overexpressing sialic acid on the membrane. Under appropriate near‐infrared irradiation, the photothermal properties of SiNWAs endow this system with high efficiency to deliver biomacromolecules into the captured cells by a membrane disruption mechanism. The cells thus “engineered” can be harvested simply by treatment with a nontoxic sugar solution, thereby maintaining good viability for subsequent applications. This method appears to have strong potential for the intracellular delivery of diverse biomacromolecules into both surface adherent and suspension cells, including hard‐to‐transfect suspension T cells, and may open up new pathways for engineering living cells.

Although electrospun nanofibers have been used to deliver functional genes into cells attached to the surface of the nanofibers, the controllable release of genes from nanofibers and the subsequent gene transfection with high efficiency remain challenging. Herein, photothermally activated electrospun hybrid nanofibers are developed for high-efficiency surface-mediated gene transfection. Nanofibers with a core−sheath structure are fabricated using coaxial electrospinning. Plasmid DNA (pDNA) encoding basic fibroblast growth factor is encapsulated in the fiber core, and gold nanorods with photothermal properties are embedded in the fiber sheath composed of poly(L-lactic acid) and gelatin. The nanofiber mats show excellent and controllable photothermal response under near-infrared irradiation. The permeability of the nanofibers is thereby enhanced to allow the rapid release of pDNA. In addition, transient holes are formed in the membranes of NIH-3T3 fibroblasts attached to the mat, thus facilitating delivery and transfection with pDNA and leading to increased proliferation and migration of the transfected cells in vitro. This work offers a facile and reliable method for the regulation of cell function and cell behavior via localized gene transfection, showing great potential for application in tissue engineering and cell-based therapy.

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