Chaoxu Li

Biodegradable nanocomposites of amyloid fibrils and graphene with shape-memory and enzyme-sensing properties

Graphene has exceptional mechanical and electronic properties, but its hydrophobic nature is a disadvantage in biologically related applications. Amyloid fibrils are naturally occurring protein aggregates that are stable in solution or under highly hydrated conditions, have well-organized supramolecular structures and outstanding strength. Here, we show that graphene and amyloid fibrils can be combined to create a new class of biodegradable composite materials with adaptable properties. This new composite material is inexpensive, highly conductive and can be degraded by enzymes. Furthermore, it can reversibly change shape in response to variations in humidity, and can be used in the design of biosensors for quantifying the activity of enzymes. The properties of the composite can be fine-tuned by changing the graphene-to-amyloid ratio.

The interplay between carbon nanomaterials and amyloid fibrils in bio-nanotechnology

Recent advances in bio-nanotechnology have not only rapidly broadened the applications and scope of hybrid nanomaterials in biological fields, but also greatly enriched the examples of ordered materials based on supramolecular self-assembly. Among eminent examples of functional nanostructured materials of undisputed impact in nanotechnology and biological environments, carbon nanomaterials (such as fullerenes, carbon nanotubes and graphene) and amyloid fibrils have attracted great attention because of their unique architectures and exceptional physical properties. Nonetheless, combination of these two classes of nanomaterials into functional hybrids is far from trivial. For example, the presence of carbon nanomaterials can offer either an inhibitory effect or promotion of amyloid fibrillation, depending on the structural architectures of carbon nanomaterials and the starting amyloid proteins/peptides considered. To date, numerous studies have been devoted to evaluating both the biological toxicity of carbon nanomaterials and their use in developing therapies for amyloidosis. At the same time, hybridization of these two classes of nanomaterials offers new possibilities for combining some of their desirable properties into nanocomposites of possible use in electronics, actuators, sensing, biomedicine and structural materials. This review describes recent developments in the hybridization of carbon nanomaterials and amyloid fibrils and discusses the current state of the art on the application of carbon nanomaterial-amyloid fibril hybrids in bio-nanotechnology.

Hybrid Nanocomposites of Gold Single‐Crystal Platelets and Amyloid Fibrils with Tunable Fluorescence, Conductivity, and Sensing Properties

Gold single-crystal platelets with high aspect ratio are combined with amyloid fibrils to design a new class of hybrid nanocomposites. The films gather physical properties from both constituents, for example, plasmon resonance, fluorescence, and water-dependent conductivities ranging from insulating to metallic levels, yet mirroring gold within a broad range of composition, and can serve multiple purposes such as sensors, diagnostic, printed electronics, micromechanical, and biological devices.

Modulating Materials by Orthogonally Oriented β-Strands: Composites of Amyloid and Silk Fibroin Fibrils

Amyloid fibrils and silk fibroin (SF) fibrils are proteinaceous aggregates occurring either naturally or as artificially reconstituted fibrous systems, in which the constituent β-strands are aligned either orthogonally or parallel to the fibril main axis, conferring complementary physical properties. Here, it is shown how the combination of these two classes of protein fibrils with orthogonally oriented β-strands results in composite materials with controllable physical properties at the molecular, mesoscopic, and continuum length scales.

Tunable Carbon Nanotube/Protein Core‐Shell Nanoparticles with NIR‐ and Enzymatic‐Responsive Cytotoxicity

A unique procedure is developed to capture carbon nanotubes into closed virus-like protein cages with a controllable shell. The cross-linked shell varies in thickness within ≈10(0) -10(2) nm, and can be entirely removed by enzyme degradation. The cytotoxicity is entirely suppressed, but can be promoted again by enzymes and near-infrared light. These hybrids can be decorated with functional inorganic nanoparticles or processed into nanocomposites.

Functionalization of Multiwalled Carbon Nanotubes and Their pH-Responsive Hydrogels with Amyloid Fibrils

New biocompatible, pH-responsive, and fully fibrous hydrogels have been prepared based on amyloid fibrils hybridized and gelled by functionalized multiwalled carbon nanotubes (MWNTs) far below the gelling concentration of amyloid fibrils. Sulfonic functional groups were introduced on the surfaces of MWNTs either by a covalent diazonium reaction or by physical π-π interactions. The presence of the isoelectric point of amyloid fibrils allows a reversible gelling behavior through ionic interactions with functionalized MWNTs.

New biocompatible thermo-reversible hydrogels from PNiPAM-decorated amyloid fibrils

New biocompatible temperature-responsive hydrogels have been obtained by using unprecedented low concentration of amyloid fibril-PNiPAM hybrids. The viscoelasticity of the hydrogels can be finely controlled by tuning the PNiPAM layers without changing the structure or concentration of the amyloid fibrils.

Macroscopic single-crystal gold microflakes and their devices.

A facile, green procedure is proposed to synthesize single-crystal gold microflakes with planar area up to 10(4) mu m(2). This unprecedented dimension offers new possibilities in designing flexible conductive films with tunable strain-dependent conductivity, that can be exploited in strain/force/vibration sensing devices. By using top-down micro-/nanofabrication techniques, these materials may further find use in single-crystal electronics and plasmonic applications.

Bioinspired Coupling of Inorganic Layered Nanomaterials with Marine Polysaccharides for Efficient Aqueous Exfoliation and Smart Actuating Hybrids

WS2 and marine alginate are perfectly coupled to ensure scalable production of exfoliated WS2 with unprecedented efficiency, further providing super mechanical properties and the photothermal effect to their composites. Combined with the water-intake and cation-binding capabilities of alginate, biomimetic soft devices are designed with stimuli-responsiveness and actuating properties, capable of serving as a photo-driven motor, a walking robot, and a gripper.

Crab Chitin-Based 2D Soft Nanomaterials for Fully Biobased Electric Devices

2D nanomaterials have various size/morphology-dependent properties applicable in electronics, optics, sensing, and actuating. However, intensively studied inorganic 2D nanomaterials are frequently hindered to apply in some particular and industrial fields, owing to harsh synthesis, high-cost, cytotoxicity, and nondegradability. Endeavor has been made to search for biobased 2D nanomaterials with biocompatibility, sustainability, and biodegradability. A method of hydrophobization-induced interfacial-assembly is reported to produce an unprecedented type of nanosheets from marine chitin. During this process, two layers of chitin aggregations assemble into nanosheets with high aspect ratio. With super stability and amphiphilicity, these nanosheets have super ability in creating highly stable Pickering emulsions with internal phase up to 83.4% and droplet size up to 140 μm, in analogue to graphene oxide. Combining emulsifying and carbonization can further convert these 2D precursors to carbon nanosheets with thickness as low as ≈3.8 nm. Having biologic origin, conductivity, and dispersibility in various solvents, resultant carbon nanosheets start a new scenario of exploiting marine resources for fully biobased electric devices with sustainability and biodegradability, e.g., supercapacitor, flexible circuits, and electronic sensors. Hybrid films of chitin and carbon nanosheets also offer low-cost and environment-friendly alternative of conductive components desirable in green electronics, wearable electronics, biodegradable circuits, and biologic devices.