Bionanointerfaces

Cells of all types take cues from the surfaces they encounter in their environment. The cells extract any or all of the mechanical, chemical, spatial, and even temporal information from the surface, but which features they read and how they integrate and translate them into specific behavioral responses is still almost a black box. 

Projects

Vascularized self-lubricating surfaces

Fig. 1: Bio-inspired vascularized fouling-release surfaces.
Fig. 2: Bio-inspired vacularized fouling-release surfaces.
Fig. 3: (A) Schematic of the process to make either infused PDMS or vascularized, infused PDMS. For simple infused PDMS (upper row), cured PDMS is placed in a bath of silicone oil which diffuses into the PDMS solid. For vascularized PDMS, the vascular pattern is created before curing. The sample is then infused externally with silicone oil in the same manner as the non-vascularized PDMS, or internally through filling the vascular network, or both. (B) Methods of creating vascular networks within PDMS: 1) An encased network is created using a 3D mold (a) to create the pattern in PDMS (b). The mold is removed from the cured PMDS (c) and the pattern is covered with a second sheet of PDMS (d and e) which is chemically bonded to the pattern using plasma. (i) an image of a 3D leaf vasculature network after encasing. 2) An embedded network is created following the procedures developed by Lewis et al. (citation). (a) A pattern of 20% w/w pluronic F127 gel at 25 °C is embedded in uncured PDMS. (b) The PDMS is allowed to cure, cooled to 4 °C, and the liquid pluronic is evacuated. (c) The channel is refilled with silicone oil. (i) An image of fluorescently dyed PDMS in a hand-drawn sinuous channel, (ii) a hand-drawn leaf-shape network, and (iii) a 3D-printed linear network.
Fig. 6: (A) Surface coverage of biofilm remaining on lubricant-infused PDMS versus glass control surfaces after incubation in and removal from the liquid medium containing C. reinhardtii, D. salina, or N. oculata. For all three species, there was a significant reduction in the amount of biofilm remaining on the SLIPS surfaces (P < 0.05). (B) Images of the substrates used in the analysis.

We have recently developed a technique for fabricating nanostructured surfaces that enables us to choose and independently vary any combination of geometry, spacing, stiffness, and chemistry, and are using it to analyze how surface features direct bacterial assembly, mammalian cell development, and marine invertebrate settlement at a level of systematic detail that was previously not possible.

As our insight into the cell-nanosurface interface develops, the same fabrication technique will enable us to design and construct surfaces that encode instructions for cell behavior for purposes ranging from anti-biofilm coatings to neural chips to organ development scaffolds.

Sunny S, Cheng G, Daniel D, Lo P, Ochoa S, Howell C, Vogel N, Majid A, Aizenberg J. Transparent antifouling material for improved operative field visibility in endoscopy. Proceedings of the National Academy of Sciences of the United States of America [Internet]. 2016;113 (42) :11676-11681. Publisher's VersionAbstract

Inspection devices are frequently occluded by highly contaminating fluids that disrupt the visual field and their effective operation. These issues are particularly striking in endoscopes, where the diagnosis and treatment of diseases are compromised by the obscuring of the operative field by body fluids. Here we demonstrate that the application of a liquid-infused surface coating strongly repels sticky biological secretions and enables an uninterrupted field of view. Extensive bronchoscopy procedures performed in vivo on a porcine model shows significantly reduced fouling, resulting in either unnecessary or ∼10–15 times shorter and less intensive lens clearing procedures compared with an untreated endoscope.

Camera-guided instruments, such as endoscopes, have become an essential component of contemporary medicine. The 15–20 million endoscopies performed every year in the United States alone demonstrate the tremendous impact of this technology. However, doctors heavily rely on the visual feedback provided by the endoscope camera, which is routinely compromised when body fluids and fogging occlude the lens, requiring lengthy cleaning procedures that include irrigation, tissue rubbing, suction, and even temporary removal of the endoscope for external cleaning. Bronchoscopies are especially affected because they are performed on delicate tissue, in high-humidity environments with exposure to extremely adhesive biological fluids such as mucus and blood. Here, we present a repellent, liquid-infused coating on an endoscope lens capable of preventing vision loss after repeated submersions in blood and mucus. The material properties of the coating, including conformability, mechanical adhesion, transparency, oil type, and biocompatibility, were optimized in comprehensive in vitro and ex vivo studies. Extensive bronchoscopy procedures performed in vivo on porcine lungs showed significantly reduced fouling, resulting in either unnecessary or ∼10–15 times shorter and less intensive lens clearing procedures compared with an untreated endoscope. We believe that the material developed in this study opens up opportunities in the design of next-generation endoscopes that will improve visual field, display unprecedented antibacterial and antifouling properties, reduce the duration of the procedure, and enable visualization of currently unreachable parts of the body, thus offering enormous potential for disease diagnosis and treatment.

Clinging to crevices, E. coli thrive, Harvard press release, April 10, 2013.