Crosslinked Fibroin Nanoparticles: Investigations on Biostability, Cytotoxicity, and Cellular Internalization

Recently, crosslinked fibroin nanoparticles (FNP) using the crosslinker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC) or the polymer poly(ethylenimine) (PEI) have been developed and showed potentials as novel drug delivery systems. Thus, this study further investigated the biological properties of these crosslinked FNP by labeling them with fluorescein isothiocyanate (FITC) for in vitro studies. All formulations possessed a mean particle size of approximately 300 nm and a tunable zeta potential (−20 to + 30 mV) dependent on the amount/type of crosslinkers. The FITC-bound FNP showed no significant difference in physical properties compared to the blank FNP. They possessed a binding efficacy of 3.3% w/w, and no FITC was released in sink condition up to 8 h. All formulations were colloidal stable in the sheep whole blood. The degradation rate of these FNP in blood could be controlled depending on their crosslink degree. Moreover, no potential toxicity in erythrocytes, Caco-2, HepG2, and 9L cells was noted for all formulations at particle concentrations of < 1 mg/mL. Finally, all FNP were internalized into the Caco-2 cells after 3 h incubation. The uptake rate of the positively charged particles was significantly higher than the negatively charged ones. In summary, the crosslinked FNP were safe and showed high potentials as versatile systems for biomedical applications.

DEVELOPMENT, EVALUATION, AND CHARACTERIZATION OF LOSARTAN POTASSIUM BUCCAL PATCHES USING JACKFRUIT POLYMER

Objective: The objective was to develop buccal patches of an antihypertensive drug and losartan potassium using jackfruit polymer for sustained buccal delivery. Methods: The patches were prepared by the solvent casting method. Five formulations were developed with varying concentrations of jackfruit polymer. USP type II apparatus was used to perform in-vitro release study under perfect sink condition. Buccal formulations were developed to a satisfactory level in terms of drug release, bioadhesive strength, content uniformity, moisture content, surface pH, thickness, and stability study. Results: From the results obtained F5 was found as best formulation, having appropriate folding endurance greater than 300, moisture content of 1.14±0.03 percentage (%), moisture uptake of 6.21±0.12%, swelling index (62.78%), bioadhesion strength (37.62±0.25 g), and bioadhesion time of 9 h 5 min. Fourier-transform infrared spectroscopy studies have shown no interactions between drug and polymer. All the formulations followed zero-order kinetics. Conclusion: It can be concluded that mucoadhesive buccal patches of losartan potassium using jackfruit polymer are an auspicious dosage form to prolong the release of drug and enhance its poor oral bioavailability.

Research on Performance of Resisting Foundation Displacement of High Voltage Electricity Transmission Tower in Mining Subsidence Area

The performance of resisting foundation displacement of a typical single return circuit transmission tower under all kinds of load conditions including foundation horizontal displacement, foundation vertical uneven downward displacement was analyzed by finite element modeling. Results showed that stability failure of single steel angle represents tower’s limit state under foundation displacement. And the corresponding foundation displacement limits were calculated. Results indicate that foundation pull condition is more dangerous than press condition. Under complex foundation displacement conditions, foundation horizontal displacement is primary factor leading to stability failure of towers. Under foundation press condition and pull condition, wind load is primary factor. Result also indicates that, tower does not fail when foundation displacements are smaller than 1.25% (under foundation press condition and pull condition) or 0.5% (under single foundation sink condition) of tower root distance.

All-Trans Retinoic Acid (atRA) Release from atRA-Loaded Folate-Poly(Ethylene Glycol)/Polyethylenimine Nanoparticles for Folate-Mediated Tumor Targeting

To improve the specific accumulation in tumor sites and aqueous solubility of atRA, the core-shell type of folate-PEG-g-PEI/atRA nanoparticles were prepared by complexation between cationic PEI segments in the copolymers and anionic charged atRA, and then characterized by 1HNMR, ELS, XRD, and TEM. In vitro atRA release from the nanoparticles was investigated as a function of drug content in sink condition. Cytotocicity of atRA against HepG2, KB cell lines were also evaluated by MTT assay. The lower the drug content, the faster atRA release. atRA incorporated in folate-PEG-g-PEI/atRA nanoparticles showed much higher cytotoxic effect compared with atRA itself.

Direct carbon emissions from Canadian forest fires, 1959-1999

Direct emissions of carbon from Canadian forest fires were estimated for all Canada and for each ecozone for the period 1959–1999. The estimates were based on a data base of large fires for the country and calculations of fuel consumption for each fire using the Canadian Forest Fire Behaviour Prediction System. This technique used the fire locations and start dates to estimate prevailing fire weather and fuel type for each of about 11 000 fires. An average of 2 × 106 ha·year–1 was burned in this period, varying from 0.3 × 106 ha in 1978 to 7.5 × 106 ha in 1989. Ecozones of the boreal and taiga areas experienced the greatest area burned, releasing most of the carbon (C). The mean area-weighted fuel consumption for all fires was 2.6 kg dry fuel·m–2 (1.3 kg C·m–2), but ecozones vary from 1.8 to 3.9 kg dry fuel·m–2. The mean annual estimate of direct carbon emissions was 27 ± 6 Tg C·year–1. Individual years ranged from 3 to 115 Tg C·year–1. These direct fire emissions represent about 18% of the current carbon dioxide emissions from the Canadian energy sector, on average, but vary from 2 to 75% among years. Post-fire effects cause an additional loss of carbon and changes to the forest sink condition.