DPA-Zinc around Polyplexes Acts Like PEG to Reduce Protein Binding While Targeting Cancer Cells.

Gene therapy holds great promise as an effective treatment for many diseases of genetic origin. Gene therapy works by employing cationic polymers, liposomes, and nanoparticles to condense DNA into polyplexes via electronic interactions. Then, a therapeutic gene is introduced into target cells, thereby restoring or changing cellular function. However, gene transfection efficiency remains low in vivo due to high protein binding, poor targeting ability, and substantial endosomal entrapment. Artificial sheaths containing PEG, anions, or zwitterions can be introduced onto the surface of gene carriers to prevent interaction with proteins; however, they reduce the cellular uptake efficacy, endosomal escape, targeting ability, thereby, lowering gene transfection. Here, it is reported that linking dipicolylamine-zinc (DPA-Zn) ions onto polyplex nanoparticles can produce a strong hydration water layer around the polyplex, mimicking the function of PEGylation to reduce protein binding while targeting cancer cells, augmenting cellular uptake and endosomal escape. The polyplexes with a strong hydration water layer on the surface can achieve a high gene transfection even in a 50% serum environment. This strategy provides a new solution for preventing protein adsorption while improving cellular uptake and endosomal escape.

Function of self-forming dynamic membrane and biokinetic parameters' determination by microelectrode.

The self-forming dynamic membrane coupled bioreactor (SFDMBR), which uses coarse pore-sized material to separate solids and liquids in a bioreactor, has some advantages compared with membrane bioreactor (MBR) using micro-/ultra-filtration membranes such as low module cost and high flux. In this study, we investigate the microbial activity change of a self-forming dynamic membrane (DM) during its bio-fouling process by a microelectrode for O2. At a high flux of 40 L/m2h, the dissolved oxygen was determined to be depleted at the depth of 1.5-2.0 mm in the self-forming DM. Based on the dissolved oxygen concentration profiles in the self-forming DM, a reliable and simple model and computational procedure were developed to estimate the biokinetic parameters in the self-forming DM. Sensitivity analysis of the model revealed that the dissolved oxygen profiles are sufficiently sensitive to the maximum specific rates of oxygen uptake (q down curvemax,20), which were computed to be within the range of 3.8-11.1 mg O2/gSS h. q down curvemax,20 decreased sharply in the first 5 days with the development of the bio-fouling process in the surface cake layer of the self-forming DM and then reached a relatively steady state afterwards. The Monod half-saturation coefficient for oxygen (Ko) was computed to be in the range of 0.16-0.75 mgO2/L. In summary, the results gave new experimental evidence on the change of microbial activity in the self-forming DM during its bio-fouling process.

Adipose-derived stem cells transfected with pEGFP-OSX enhance bone formation during distraction osteogenesis.

This study was designed to investigate the effects of local delivery of adipose-derived stem cells (ADSCs) transfected with transcription factor osterix (OSX) on bone formation during distraction osteogenesis. New Zealand white rabbits (n=54) were randomly divided into three groups (18 rabbits per group). A directed cloning technique was used for the construction of recombinant plasmid pEGFP-OSX, where EGFP is the enhanced green fluorescence protein. After osteodistraction of the right mandible of all experimental rabbits, rabbits in group A were treated with ADSCs transfected with pEGFP-OSX, group B with ADSCs transfected with pEGFP-N1, and group C with physiological saline. Radiographic and histological examinations were processed after half of the animals within each group were humanely killed by injection of sodium pentothal at Week 2 or 6 after surgery. The distraction bone density was measured as its projectional bone mineral density (BMD). Three parameters were measured, namely, the thickness of new trabeculae (TNT), and the volumes of the newly generated cortical bone (NBV1) and the cancellous bone (NBV2) of the distracted regions. Good bone generation in the distraction areas was found in group A, which had the highest BMD, TNT, and NBV in the distraction zones among the groups. There was no significant difference in bone generation in the distraction areas between groups B and C. The results indicate that the transplantation of ADSCs transfected with pEGFP-OSX can effectively promote bone generation during distraction in vivo.

[Study on denitrification characteristics of dynamic membrane based on nitrate liquid-membrane microelectrodes].

Nitrate microelectrodes and ORP microelectrodes were fabricated to study the denitrification characteristics of dynamic membrane at different COD loadings. The denitrification process was found at 0.6-1 mm depth beneath the interface of biofilm/bulk. The results of ORP microelectrode also demonstrated that the ORP value in the range of denitrification area was between 88.6 approximately -128.4 mV which was appropriate to denitrification. When the COD loading was 0.45 kg/(m3 x d), the denitrification rate (NO3- -N) was the maximum of 0.6347 x 10(-6 mol/(L x s). With the increase of COD loading, the denitrification area was increasing and two layers with different denitrification rates emerged in the dynamic membrane. The phenomenon implied the effect of organic concentration, oxygen concentration and bacterial competition on the denitrification rate.

[Characteristics of dynamic membrane based on oxygen microelectrode].

Self-forming dynamic membrane coupled bioreactor is a technology using coarse pore-sized material modules to separate solid and liquid in the activated sludge. The cake layer formed on the coarse pore-sized material, i.e. dynamic membrane, can remove turbidity efficiently and some organic pollutants. Its biological activity can be studied by microelectrode. For measurement in-situ, a small bioreactor is designed to simulate the real filtration process. A microelectrode with micromanipulator is used to measure the dissolved oxygen profile in the dynamic membrane. The results indicate that bubble emerged in the dynamic membrane during operation of bioreactor. The dissolved oxygen concentration decreased with the increasing depth, and fell to 0 at 2.0 - 2.5mm depth. The specific oxygen uptake rates of the surface part of dynamic membrane were calculated to be 34.3, 10.6 and 12.4 mg/(g x h) respectively at the 1st, 5th and 8th day of the filtration.