42 research outputs found
Fabrication of biomolecule–copolymer hybrid nanovesicles as energy conversion systems
This work demonstrates the integration of the energy-transducing proteins bacteriorhodopsin (BR) from Halobacterium halobium and cytochrome c oxidase (COX) from Rhodobacter sphaeroides into block copolymeric vesicles towards the demonstration of coupled protein functionality. An ABA triblock copolymer-based biomimetic membrane possessing UV-curable acrylate endgroups was synthesized to serve as a robust matrix for protein reconstitution. BR-functionalized polymers were shown to generate light-driven transmembrane pH gradients while pH gradient-induced electron release was observed from COX-functionalized polymers. Cooperative behaviour observed from composite membrane functionalized by both proteins revealed the generation of microamp-range currents with no applied voltage. As such, it has been shown that the fruition of technologies based upon bio-functionalizing abiotic materials may contribute to the realization of high power density devices inspired by nature
Emulsion Electrospinning of Polytetrafluoroethylene (PTFE) Nanofibrous Membranes for High-Performance Triboelectric Nanogenerators
Electrospinning
is a simple, versatile technique for fabricating
fibrous nanomaterials with the desirable features of extremely high
porosities and large surface areas. Using emulsion electrospinning,
polytetrafluoroethylene/polyethene oxide (PTFE/PEO) membranes
were fabricated, followed by a sintering process to obtain pure PTFE
fibrous membranes, which were further utilized against a polyamide
6 (PA6) membrane for vertical contact-mode triboelectric nanogenerators
(TENGs). Electrostatic force microscopy (EFM) measurements of the
sintered electrospun PTFE membranes revealed the presence of both
positive and negative surface charges owing to the transfer of positive
charge from PEO which was further corroborated by FTIR measurements.
To enhance the ensuing triboelectric surface charge, a facile negative
charge-injection process was carried out onto the electrospun (ES)
PTFE subsequently. The fabricated TENG gave a stabilized peak-to-peak
open-circuit voltage (<i>V</i><sub>oc</sub>) of up to ∼900
V, a short-circuit current density (<i>J</i><sub>sc</sub>) of ∼20 mA m<sup>–2</sup>, and a corresponding charge
density of ∼149 μC m<sup>–2</sup>, which are ∼12,
14, and 11 times higher than the corresponding values prior to the
ion-injection treatment. This increase in the surface charge density
is caused by the inversion of positive surface charges with the simultaneous
increase in the negative surface charge on the PTFE surface, which
was confirmed by using EFM measurements. The negative charge injection
led to an enhanced power output density of ∼9 W m<sup>–2</sup> with high stability as confirmed from the continuous operation of
the ion-injected PTFE/PA6 TENG for 30 000 operation cycles,
without any significant reduction in the output. The work thus introduces
a relatively simple, cost-effective, and environmentally friendly
technique for fabricating fibrous fluoropolymer polymer membranes
with high thermal/chemical resistance in TENG field and a direct ion-injection
method which is able to dramatically improve the surface negative
charge density of the PTFE fibrous membranes
Recent Progress in Advanced Nanobiological Materials for Energy and Environmental Applications
In this review, we briefly introduce our efforts to reconstruct cellular life processes by mimicking natural systems and the applications of these systems to energy and environmental problems. Functional units of in vitro cellular life processes are based on the fabrication of artificial organelles using protein-incorporated polymersomes and the creation of bioreactors. This concept of an artificial organelle originates from the first synthesis of poly(siloxane)-poly(alkyloxazoline) block copolymers three decades ago and the first demonstration of protein activity in the polymer membrane a decade ago. The increased value of biomimetic polymers results from many research efforts to find new applications such as functionally active membranes and a biochemical-producing polymersome. At the same time, foam research has advanced to the point that biomolecules can be efficiently produced in the aqueous channels of foam. Ongoing research includes replication of complex biological processes, such as an artificial Calvin cycle for application in biofuel and specialty chemical production, and carbon dioxide sequestration. We believe that the development of optimally designed biomimetic polymers and stable/biocompatible bioreactors would contribute to the realization of the benefits of biomimetic systems. Thus, this paper seeks to review previous research efforts, examine current knowledge/key technical parameters, and identify technical challenges ahead
An injectable peptide hydrogel for reconstruction of the human trabecular meshwork
Glaucoma is a leading cause of irreversible blindness worldwide. Current treatments of glaucoma involve lowering the IOP by means of decreasing aqueous humor production or increasing non-trabecular aqueous humor outflow with the help of IOP-lowering eye drops, nanotechnology enabled glaucoma drainage implants, and trabeculectomy. However, there is currently no effective and permanent cure for this disease. In order to investigate new therapeutic strategies, three dimensional (3D) biomimetic trabecular meshwork (TM) models are in demand. Therefore, we adapted MAX8B, a peptide hydrogel system to bioengineer a 3D trabecular meshwork scaffold. We assessed mechanical and bio-instructive properties of this engineered tissue matrix by using rheological analysis, 3D cell culture and imaging techniques. The scaffold material exhibited shear-thinning ability and biocompatibility for proper hTM growth and proliferation indicating a potential utilization as an injectable implant. Additionally, by using a perfusion system, MAX8B scaffold was tested as an in vitro platform for investigating the effect of Dexamethasone (Dex) on trabecular meshwork outflow facility. The physiological response of hTM cells within the scaffold to Dex treatment clearly supported the effectiveness of this 3D model as a drug-testing platform, which can accelerate discovery of new therapeutic targets for glaucoma. Statement of significance: Artificial 3D-TM (3-dimentional Trabecular Meshwork) developed here with hTM (human TM) cells seeded on peptide-hydrogel scaffolds exhibits the mechanical strength and physiological properties mimicking the native TM tissue. Besides serving a novel and effective 3D-TM model, the MAX8B hydrogel could potentially function as an injectable trabecular meshwork implant
Antifouling Cellulose Hybrid Biomembrane for Effective Oil/Water Separation
Oil/water
separation has been of great interest worldwide because of the increasingly
serious environmental pollution caused by the abundant discharge of
industrial wastewater, oil spill accidents, and odors. Here, we describe
simple and economical superhydrophobic hybrid membranes for effective
oil/water separation. Eco-friendly, antifouling membranes were fabricated
for oil/water separation, waste particle filtration, the blocking
of thiol-based odor materials, etc., by using a cellulose membrane
(CM) filter. The CM was modified from its original superhydrophilic
nature into a superhydrophobic surface via a reversible addition–fragmentation
chain transfer technique. The block copolymer poly{[3-(trimethoxysilyl)propyl
acrylate]-<i>block</i>-myrcene} was synthesized using a
“grafting-from” approach on the CM. The surface contact
angle that we obtained was >160°, and absorption tests of
several organic contaminants (oils and solvents) exhibited superior
levels of extractive activity and excellent reusability. These properties
rendered this membrane a promising surface for oil/water separation.
Interestingly, myrcene blocks thiol (through “-ene-”
chemistry) contaminants, thereby bestowing a pleasant odor to polluted
water by acting as an antifouling material. We exploited the structural
properties of cellulose networks and simple chemical manipulations
to fabricate an original material that proved to be effective in separating
water from organic and nano/microparticulate contaminants. These characteristics
allowed our material to effectively separate water from oily/particulate
phases as well as embed antifouling materials for water purification,
thus making it an appropriate absorber for chemical processes and
environmental protection
Peptides for targeting βB2-crystallin fibrils
Crystallins are a major family of proteins located within the lens of the eye. Cataracts are thought to be due to the formation of insoluble fibrillar aggregates, which are largely composed of proteins from the crystallin family. Today the only cataract treatment that exists is surgery and this can be difficult to access for individuals in the developing world. Development of novel pharmacotherapeutic approaches for the treatment of cataract rests on the specific targeting of these structures. βB2-crystallin, a member of β-crystallin family, is a large component of the crystallin proteins within the lens, and as such was used to form model fibrils in vitro. Peptides were identified, using phage display techniques, that bound to these fibrils with high affinity. Fibrillation of recombinantly expressed human βB2-crystallin was performed in 10% (v/v) trifluoroethanol (TFE) solution (pH 2.0) at various temperatures, and its amyloid-like structure was confirmed using Thioflavin-T (ThT) assay, transmission electron microscopy (TEM), and X-ray fiber diffraction (XRFD) analysis. Affinity of identified phage-displayed peptides were analyzed using enzyme-linked immunosorbent assay (ELISA). Specific binding of a cyclic peptide (CKQFKDTTC) showed the highest affinity, which was confirmed using a competitive inhibition assay