Preparation of supermacroporous cryogels with improved mechanical strength for efficient purification of lysozyme from chicken egg white.

A novel, facile, and robust strategy was proposed to increase the pore size and mechanical strength of cryogels. By mixing the monomers of acrylamide and 2-hydroxyethyl methacrylate as the precursor, a monolithic copolymer cryogel with large interconnected pores and thick pore walls was prepared. Hydrogen bonding between the two monomers contributed to the entanglement and aggregation of the copolymers, thickening the pore walls and resulting in larger pore sizes. Analysis via mercury porosimetry demonstrated that the interconnected pore diameter of the copolymer cryogel ranged from 10-350 µm, which was far larger than that of the cryogels from one monomer (10-50 µm). Additionally, the thicker pore walls of the copolymer cryogel improved its mechanical strength. Affinity cryogels were prepared through covalent immobilization using Tris(hydroxymethyl)aminomethane as a coupling agent, and the affinity binding of lysozymes on Tris-cryogel was evaluated by the Langmuir isothermal adsorption with the maximum adsorption capacity of 360 mg/g. Compared with that of the Tris-cryogels produced from one monomer, the copolymer Tris-cryogel exhibited higher adsorption capacity and lysozyme purity, when the chicken egg white solution flowed solely driven by gravity. This work provides a new avenue for designing and developing supermacroporous cryogels for bioseparation.

Supramolecularly Assembled Nanocomposites as Biomimetic Chloroplasts for Enhancement of Photophosphorylation.

Prototypes of natural biosystems provide opportunities for artificial biomimetic systems to break the limits of natural reactions and achieve output control. However, mimicking unique natural structures and ingenious functions remains a challenge. Now, multiple biochemical reactions were integrated into artificially designed compartments via molecular assembly. First, multicompartmental silica nanoparticles with hierarchical structures that mimic the chloroplasts were obtained by a templated synthesis. Then, photoacid generators and ATPase-liposomes were assembled inside and outside of silica compartments, respectively. Upon light illumination, protons produced by a photoacid generator in the confined space can drive the liposome-embedded enzyme ATPase towards ATP synthesis, which mimics the photophosphorylation process in vitro. The method enables fabrication of bioinspired nanoreactors for photobiocatalysis and provides insight for understanding sophisticated biochemical reactions.

Molecular Assembly of Polysaccharide-Based Microcapsules and Their Biomedical Applications.

Advanced multifunctional microcapsules have revealed great potential in biomedical applications owing to their tunable size, shape, surface properties, and stimuli responsiveness. Polysaccharides are one of the most acceptable biomaterials for biomedical applications because of their outstanding virtues such as biocompatibility, biodegradability, and low toxicity. Many efforts have been devoted to investigating novel molecular design and efficient building blocks for polysaccharide-based microcapsules. In this Personal Account, we first summarize the common features of polysaccharides and the main principles of the design and fabrication of polysaccharide-based microcapsules, and further discuss their applications in biomedical areas and perspectives for future research.

Transporting a tube in a tube.

LbL-assembled tubes were employed for micro/nanoscale cargo transportation through the kinesin-microtubule system. Selectively modified with kinesins onto the inner tube walls through Ni-NTA complexes, these tubes can work as channels for microtubules. A motility assay shows the smooth movement of microtubules along the tube inner wall powered by the inside immobilized kinesins. It could be envisioned that cargoes with different sizes can be transported through these tubular channels with little outside interruption.

Self-assembly of hierarchical nanostructures from dopamine and polyoxometalate for oral drug delivery.

The preparation of 3D hierarchical nanostructures by a simple and versatile strategy of self-assembly of dopamine (DA) and phosphotungstic acid (PTA) is described. The size and morphology of the hierarchical nanostructures could be simply controlled by varying the ratio of the two components, their concentrations, and the pH of the initial Tris-HCl solution. The self-assembly of the flowerlike microspheres has been found to involve a two-stage growth process. Moreover, use of the hierarchical nanostructures as a possible carrier for an anticancer drug in chemotherapy has been explored. The nanostructures showed an intriguing pH-dependent release behavior, making them promising for applications in biomedical science.

[G6PD deficiency among children under 7 years old from Yunnan with unique ethnic minority origin].

OBJECTIVE: To investigate the epidemiological status of glucose-6-phosphate dehydrogenase (G6PD) deficiency among children from Yunnan with unique ethnic origins. METHODS: DNA samples from 11759 children were tested with fluorescent spot test, G6PD/6PGD quantitative ratio assay and hemoglobin electrophoresis. RESULTS: The detection rate of G6PD deficiency was 2.5%, for which boys were significantly greater than girls (3.5% vs. 1.4%, P<0.05). Significant differences were also detected among children from different ethnic groups and different regions. For ethnic Han Chinese, the detection rate was 0.7%, which was lower than the majority of ethnic minorities. By regression analysis, altitude of residence and family history both have significant influence on the calculated rate. CONCLUSION: Occurrence of G6PD deficiency seems to be influenced by gender. It also varies substantially between different ethnic groups as well as regions, e.g., more common in south. It also showed a declining trend after years of diagnosis and intervention. This survey may provide a valuable basis for counseling of G6PD deficiency in Yunnan.

Freezing-triggered gelation of quaternized chitosan reinforced with microfibrillated cellulose for highly efficient removal of bilirubin.

The highly efficient removal of bilirubin from blood by hemoperfusion for liver failure therapy remains a challenge in the clinical field due to the low adsorption capacity and poor hemocompatibility of currently used carbon-based adsorbents. Polysaccharide-based cryogels seem to be promising candidates for hemoperfusion adsorbents owing to their inherited excellent hemocompatibility. However, the weak mechanical strength and relatively low adsorption capacity of polysaccharide-based cryogels limited their application in bilirubin adsorption. In this work, we presented a freezing-triggered strategy to fabricate QCS/MFC cryogels, which were formed by quaternized chitosan (QCS) crosslinked with divinylsulfonyl methane (BVSM) and reinforced with microfibrillated cellulose (MFC). Ice crystal exclusions triggered the chemical crosslinking to generate the cryogels with dense pore walls. The obtained QCS/MFC cryogels were characterized by FTIR, SEM, stress-strain test, and hemocompatibility assay, which exhibited interconnected macroporous structures, excellent shape-recovery and mechanical performance, and outstanding blood compatibility. Due to the quaternary ammonium functionalization of chitosan, the QCS/MFC showed a high adsorption capacity of 250 mg g-1 and a short adsorption equilibrium time of 3 h. More importantly, the QCS/MFC still exhibited high adsorption efficiency (over 49.7%) in the presence of 40 g L-1 albumin. Furthermore, the QCS/MFC could also maintain high dynamic adsorption efficiency in self-made hemoperfusion devices. This facile approach provides a new avenue to develop high-performance hemoperfusion adsorbents for bilirubin removal, showing great promise for the translational therapy of hyperbilirubinemia.

Shapeable and underwater super-elastic cellulose nanofiber/alginate cryogels by freezing-induced oxa-Michael reaction for efficient protein purification.

Construction of monolithic cryogels that can efficiently adsorb proteins is of great significance in biotechnological and pharmaceutical industries. Herein, a novel approach is presented to fabricate microfibrillated cellulose (MFC)/sodium alginate (SA) cryogels by using freezing-induced oxa-Michael reaction at -12 °C. Thanks to the controllable reactiveness of divinyl sulfone (DVS), cryo-concentrated pH increase activates the oxa-Michael reaction between DVS and hydroxyl groups of MFCs and SAs. The obtained composite cryogel exhibits outstanding underwater shape recovery and excellent fatigue resistance. Moreover, the MFC/SAs reveal a high lysozyme adsorption capacity of 294.12 mg/g, surpassing most of absorbent materials previously reported. Furthermore, the cryogel-packed column can purify lysozyme continuously from chicken egg white, highlighting its outstanding practical application performance. Reuse experiments indicated that over 90% of lysozyme extraction capacity was retained after 6 cycles. This work provides a new avenue to design and develop next-generation chromatographic media of natural polysaccharide-based cryogel for protein purification.

Facile fabrication of robust polydopamine microcapsules for insulin delivery.

Inspired by the composition of adhesive proteins in mussel, a facile, low-cost, and green approach to construct robust polydopamine (PDA) microcapsules as carriers for insulin delivery is developed. The morphology and shell thickness of the capsules could be tuned by varying the concentration of dopamine or the pH of Tris-HCl buffer. The PDA capsules are stable enough for long-term storage and transportation in practical application. The fluorescent property of PDA capsules labeled with FITC is beneficial in monitoring the safety and efficacy of drug carriers. Furthermore, the PDA shell coated insulin particles exhibit pH-responsive release behavior, making them promising for the oral administration of insulin in diabetic patients.

One-pot mass self-assembly of MnO2 sponge-like hierarchical nanostructures through a limited hydrothermal reaction and their environmental applications.

We report an environmentally-responsible limited hydrothermal reaction to construct gram-scale MnO2 sponge-like hierarchical nanostructures composed of ultrathin nanosheets (∼5nm) in one pot. This template-free strategy simultaneously avoids the disposal of toxic materials and provides novel metal oxide nanostructures. As a typical application, the MnO2 hierarchical nanostructures prepared can easily remove positively-charged methylene blue in water with much more adsorption capacity than those of commercial carbon grain and MnO2 microparticles, TiO2 and Fe2O3 nanoparticles. Meanwhile, the solid-liquid separation is ready due to higher density resulted from their hierarchical nanostructures. Importantly adsorbed methylene blue can be reclaimed after elution with ethanol. Remarkably, the sponge-like hierarchical nanostructures can be recycled for many times with no obvious loss of adsorption capacity, qualifying them as a great potential application in environmental protection and resource reuse.

Coassembly of Photosystem II and ATPase as Artificial Chloroplast for Light-Driven ATP Synthesis.

Adenosine triphosphate (ATP) is one of the most important energy sources in living cells, which can drive serial key biochemical processes. However, generation of a proton gradient for ATP production in an artificial way poses a great challenge. In nature, photophosphorylation occurring in chloroplasts is an ideal prototype of ATP production. In this paper we imitate the light-to-ATP conversion process occurring in the thylakoid membrane by construction of FoF1-ATPase proteoliposome-coated PSII-based microspheres with well-defined core@shell structures using molecular assembly. Under light illumination, PSII can split water into protons, oxygen, and electrons and can generate a proton gradient for ATPase to produce ATP. Thus, an artificially designed chloroplast for PSII-driven ATP synthesis is realized. This biomimetic system will help to understand the photophosphorylation process and may facilitate the development of ATP-driven devices by remote light control.

A self-powered kinesin-microtubule system for smart cargo delivery.

A smart self-powered cargo delivery system that is composed of creatine phosphate kinase (CPK) microspheres, kinesins and microtubules is demonstrated. The CPK microsphere not only acts as an ATP generation and buffering system, but also as a carrier for cargo transport, thus realizing the easy loading and self-powered delivery of cargos at the same time.

Co-assembly of photosystem II/reduced graphene oxide multilayered biohybrid films for enhanced photocurrent.

A new type of biohybrid photo-electrochemical cell was fabricated by layer-by-layer assembly of photosystem II and reduced graphene oxide. We demonstrate that the photocurrent in the direct electron transfer is enhanced about two fold with improved stability. The assembly strategy without any cross-linker or additional electron mediators makes the cell fabrication and operation much simpler as compared to previous approaches. This work may open new routes for the construction of solar energy conversion systems based on photoactive proteins and graphene materials.