Long-Chain Lipids Facilitate Insertion of Large Nanoparticles into Membranes of Small Unilamellar Vesicles.

Insertion of hydrophobic nanoparticles into phospholipid bilayers is limited to small particles that can incorporate into a hydrophobic membrane core between two lipid leaflets. Incorporation of nanoparticles above this size limit requires the development of challenging surface engineering methodologies. In principle, increasing the long-chain lipid component in the lipid mixture should facilitate incorporation of larger nanoparticles. Here, we explore the effect of incorporating very long phospholipids (C24:1) into small unilamellar vesicles on the membrane insertion efficiency of hydrophobic nanoparticles that are 5-11 nm in diameter. To this end, we improve an existing vesicle preparation protocol and utilized cryogenic electron microscopy imaging to examine the mode of interaction and evaluate the insertion efficiency of membrane-inserted nanoparticles. We also perform classical coarse-grained molecular dynamics simulations to identify changes in lipid membrane structural properties that may increase insertion efficiency. Our results indicate that long-chain lipids increase the insertion efficiency by preferentially accumulating near membrane-inserted nanoparticles to reduce the thermodynamically unfavorable disruption of the membrane.

High production of poly(3-hydroxybutyrate) in Escherichia coli using crude glycerol.

Poly(3-hydroxybutyrate) (PHB) is a prominent bio-plastic and recognized as the potential replacement of petroleum-derived plastics. To make PHB cost-effective, the production scheme based on crude glycerol was developed using Escherichia coli. The heterogeneous synthesis pathway of PHB was introduced into the E. coli strain capable of efficiently utilizing glycerol. The central metabolism that links to the synthesis of acetyl-CoA and NADPH was further reprogrammed to improve the PHB production. Key genes were targeted for manipulation, involving those in glycolysis, the pentose phosphate pathway, and the tricarboxylic cycle. As a result, the engineered strain gained a 22-fold increase in the PHB titer. Finally, the fed-batch fermentation was conducted with the producer strain to give the PHB titer, content, and productivity reaching 36.3 ± 3.0 g/L, 66.5 ± 2.8%, and 1.2 ± 0.1 g/L/h, respectively. The PHB yield on crude glycerol accounts for 0.3 g/g. The result indicates that the technology platform as developed is promising for the production of bio-plastics.

Drug-loading three-dimensional scaffolds based on hydroxyapatite-sodium alginate for bone regeneration.

Bone tissue engineering is a promising approach for tackling clinical challenges. Osteoprogenitor cells, osteogenic factors, and osteoinductive/osteoconductive scaffolds are employed in bone tissue engineering. However, scaffold materials remain limited due to their source, low biocompatibility, and so on. In this study, a composite hydrogel scaffold composed of hydroxyapatite (HA) and sodium alginate (SA) was manufactured using three-dimensional printing. Naringin (NG) and calcitonin-gene-related peptide (CGRP) were used as osteogenic factors in the fabrication of drug-loaded scaffolds. Investigation using animal experiments, as well as scanning electron microscopy, cell counting kit-8 testing, alkaline phosphatase staining, and alizarin red-D staining of bone marrow mesenchymal stem cell culture showed that the three scaffolds displayed similar physicochemical properties and that the HA/SA/NG and HA/SA/CGRP scaffolds displayed better osteogenesis than that of the HA/SA scaffold. Thus, the HA/SA scaffold could be a biocompatible material with potential applications in bone regeneration. Meanwhile, NG and CGRP doping could result in better and more positive proliferation and differentiation.

[Evaluation for two-year highly active antiretroviral therapy in Chinese HIV-1 infection patients].

OBJECTIVE: To observe that antiretroviral efficacy, immune reconstitution of two-year HAART, and evaluate its side effect in Chinese HIV-1-infected patients. METHODS: Three drug regimen composed of didanosine (ddI), stavudine (d4T), and nevirapine (NVP) was used on 27 HIV-1 infected patients, Within 2 weeks before treatment, and 3, 6, 12, 18, and 24 months after the beginning of treatment peripheral blood samples were collected to measure the HIV-RNA viral load (VL) by fluorescent quantitative polymerase chain reactions (FQ-PCR), and the counts of CD3+CD4+ cells, CD3+CD8+ cells, CD4+CD45RA+CD62L+ cells, CD4+CD45RO+ cells, CD8+CD38+ cells, and CD8+CD38+/CD3+CD8+ percentage. The side effects, blood routine, main biochemical parameters, and other disadvantageous accidents were monitored during the 24-mouth treatment period. 17 males and 10 females, aged 33 +/- 11. Thirty-one sex- and age-matched healthy persons were used as controls. RESULTS: FQ-PCR showed that the plasma HIV-1 RNA levels 2 weeks before treatment, and 3, 6, 12, 18, and 24 months after the beginning of treatment were 5.15 logs (copies/ml), 3.37 logs, 2.24 logs, 2.02 logs, 1.97 logs, and 2.15 logs respectively. 24 months after the treatment. In 56.6% (13/24) of the patients the HIV-1 VL was < 50 copies/ml 24 months after treatment, and the counts of CD3+CD4+ cells, CD4+CD45RA+62L+ cells (nave cells), and CD4+CD45RO+ cells (memory cells) 24 months after treatment were (317 +/- 175) cells/microl, (133 +/- 65) cells/microl, and (207 +/- 85) cells/microl respectively, all significantly hoi/higher than the baseline levels [(185 +/- 73) cells/microl, (51 +/- 21) cells/microl, and (115 +/- 57) cells/microl respectively]. And the CD3+CD8+ cell count, CD8+CD38+ cell count, and CD8+CD38+/CD3+CD8+ percentage decreased from (907 +/- 435) cells/microl, (614 +/- 299) cells/microl, and 67.7% to (775 +/- 303) cells/microl, (385 +/- 131) cells/microl, and 49.7% respectively, with the lowest values in the months 3 and 6. But by the month 24, all of the parameters failed to reach the normal level. 19 of the 27 patients had side effects, such as peripheral polyneuropathy, various rashes, central nervous system disorders, abdominal pain, fullness or bloating, fever, and baldness, 21 showed abnormalities in blood routine, liver function, renal function, or lipid tests and increased gamma glutamyl transferase (GGT) and amylase. The regimen had to be changed for 3 of these patients because of paresthesia and suspected lactic acidosis. CONCLUSION: The regimen with ddI, d4T and NVP foe 24 months showed a good antiretroviral effect and immune reconstitution on the HIV-1 infected persons. However, there are side effects, especially in the respect of gastrointestinal disorder and peripheral neuritis, decrease of WBC and increase of GGT and amylase.

Carbon nanotube-incorporated collagen hydrogels improve cell alignment and the performance of cardiac constructs.

Carbon nanotubes (CNTs) provide an essential 2-D microenvironment for cardiomyocyte growth and function. However, it remains to be elucidated whether CNT nanostructures can promote cell-cell integrity and facilitate the formation of functional tissues in 3-D hydrogels. Here, single-walled CNTs were incorporated into collagen hydrogels to fabricate (CNT/Col) hydrogels, which improved mechanical and electrical properties. The incorporation of CNTs (up to 1 wt%) exhibited no toxicity to cardiomyocytes and enhanced cell adhesion and elongation. Through the use of immunohistochemical staining, transmission electron microscopy, and intracellular calcium-transient measurement, the incorporation of CNTs was found to improve cell alignment and assembly remarkably, which led to the formation of engineered cardiac tissues with stronger contraction potential. Importantly, cardiac tissues based on CNT/Col hydrogels were noted to have better functionality. Collectively, the incorporation of CNTs into the Col hydrogels improved cell alignment and the performance of cardiac constructs. Our study suggests that CNT/Col hydrogels offer a promising tissue scaffold for cardiac constructs, and might serve as injectable biomaterials to deliver cell or drug molecules for cardiac regeneration following myocardial infarction in the near future.