Plasma-Induced Selective Propylene Epoxidation Using Water as the Oxygen Source

Propylene oxide (PO) is a critical gateway chemical used in large-scale production of plastics and many other compounds. In addition, PO is also used in many smaller-scale applications that require lower PO concentrations and volumes. These include its usage as a fumigant and disinfectant for food, a sterilizer for medical equipment, as well as in producing modified food such as starch and alginate. While PO is currently mostly produced in a large-scale propylene epoxidation chemical process, due to its toxic nature and high transport and storage costs, there is a strong incentive to develop PO production strategies that are well-suited for smaller-scale on-site applications. In this contribution, we designed a plasma-liquid interaction (PLI) catalytic process that uses only water and C₃H₆ as reactants to form PO. We show that hydrogen peroxide (H₂O₂) generated in the interactions of water with plasma serves as a critical oxidizing agent that can epoxidize C₃H₆ over a titanium silicate-1 (TS-1) catalyst dispersed in a water solution with a carbon-based selectivity of more than 98%. As the activity of this plasma C₃H₆ epoxidation system is limited by the rate of H₂O₂ production, strategies to improve H₂O₂ production were also investigated.

Selective adsorbent for the removal of immunoglobulin E in bronchial asthma

Agar-gel resin with tryptophan as ligand was synthesized as an adsorbent for the removal of Immunoglobulin E (IgE) in bronchial asthma. Factors affecting the adsorption properties of the adsorbent, such as the different kind of amino acid linked to the carrier, NaOH concentration and amount of epichlorohydrin used in activation, were studied in detail. The effect of spacer on the adsorption capacity was also investigated. Results showed that the agar-tryptophan adsorbent with a spacer could enhance the adsorption capacity to 70.73% (1309.403IU/g agar-gel), which was higher than that without spacers (53%). The selectivity and hemocompatibility of the adsorbent were also examined, which showed good selectivity for IgE and satisfactory blood compatibility.

Haemocompatibility of invasive sensors

In recent years the importance and utilisation of invasive chemical sensors have increased, especially in respect to their function and behaviour in a biological environment. This review aims to highlight the development of various sensors and reflect on the problems which can occur when the sensors come into contact with blood. Thus their haemocompatibility is a key area of importance. A clear understanding of their interaction with plasma proteins at the point of interface is fundamental as this determines their ultimate capability to function safely and effectively. There is also an overview of various techniques that have been developed, together with a broad summary of inherent problems which may arise when aiming to improve the haemocompatibility of invasive sensors for in vivo applications.

Manufacture of recombinant proteins with safe and validated chromatographic sorbents

Purification of recombinant proteins to achieve homogeneity, purity, consistency and potency as required for therapeutic proteins and in vivo diagnostics is performed under stringent and validated conditions. As liquid chromatography is one of the major technologies used for this purpose, it has to be carried out according to special regulatory guidelines. One of the reported aspects is the long-term consistency of a chromatographic process and validation of its operation; other aspects described are more sorbent oriented. In-place cleaning and sterilization are also very important aspects, the efficiency of which is dependent on the chosen working conditions and the chemical nature of the sorbents. Drastic cleaning may deteriorate the chromatographic matrices, releasing chemicals that may contaminate the biologicals of interest, which modifying the behaviour of the chromatographic columns. Moreover, leachable compounds, when present, could have adverse effects in case of high toxicity. Determination of leaching levels and toxicity tests are part of the validation steps to turn chromatographic separations into consistent, effective and safe production processes for biologicals.

Specific removal of IgE by therapeutic immunoadsorption system

A therapeutic immunoadsorption system was developed that can remove IgE effectively and specifically from the plasma of patients with an allergy or other hyper-IgE syndrome. The immunoadsorbent (IA) consists of immunoaffinity purified anti-IgE antibody (a-IgE ab) immobilized on controlled pore glass beads (50 nm pore size). Adsorption isotherms for IgE, which were reduced by the Freundlich adsorption equation, were obtained with IA that immobilized various amounts of a-IgE ab. An optimum amount of a-IgE ab to be immobilized was selected. IA worked sufficiently in a wide range of IgE concentrations. Clinical treatment requires an amount of 41 mg of IgE to be removed from a patient's plasma for 3 h. An IA for clinical use was designed to contain 10 g of the support binding 325 mg or more of the antibody. In fact, our study in vitro simulating a clinical case showed that serum IgE was removed by IA, as expected: the level decreased from 11,000 to 3000 U/ml after a 3 h perfusion (1 U = 2.3 ng). A very small amount of a-IgE ab (goat IgG) was found to be detached from IA by flowing plasma; the average level was 20 ng/ml, which seems to be safe. However, we installed the second column in a circuit that adsorbs a-IgE ab leaked into plasma, because the amounts of a-IgE ab infused into the patient must be minimized. The second column contained IgE immobilized on the same support, since IgE as a ligand adsorbed more a-IgE ab than did anti-goat IgG antibody. This is an effective and safe therapeutic immunoadsorption system and has been subjected to clinical tests.

Leakage of immobilized IgG from therapeutic immunoadsorbents

In developing therapeutic immunoadsorbents (IAs), antibodies (IgG molecules) covalently immobilized on porous carriers, a leak of IgG was determined both in the storage test with buffers at 25 and 4 degrees C and in contact with plasma at room temperature (RT). The amount of antibody released from therapeutic IAs must be minimized to avoid side effects during treatment. The amount of IgG released was a. Dependent on the amount of IgG immobilized b. Much greater with CNBr-activated Sepharose 4B, or Formyl-Cellulofine as a support material than with aminopropyl CPG (controlled pore glass) c. Found to yield again during another storage in buffers after the IAs were washed and their buffers replaced with fresh ones and d. Decreased after the IAs were treated with glutaraldehyde (GA) solutions. Whereas treating the IAs with GA solutions significantly reduced the amount of IgG released, it caused some deterioration of the adsorption characteristics of the IAs. An irradiation dose of 2.5 Mrad as a crosslinking procedure also reduced the amount of IgG released; its effect was comparable to that of 0.025% GA, the lowest concentration used.

Effect of pore size of porous bead carriers immobilizing antibody on IgE absorption

Immunoglobulin E (IgE) adsorption was studied using antihuman IgE antibody immobilized on alkylamine glass carriers with different pore sizes (Controlled Pore Glass [CPG]) to determine the effect of pore size on IgE absorption in therapeutic immuno-adsorbents. With a series of CPGs whose pore sizes were in the range of 170 to 1400 A, CPGs possessing pore sizes larger than 500 A had higher IgE absorption. A CPG (500-A pore size) with the spacer arm 20 A long did not give better IgE removal than CPG without the spacer arm, since the spacer prevented the immobilization of a sufficient amount of the antibody on the carrier because of steric hindrance. However, the antibodies, once immobilized on CPG with the spacer arm, bound the same amount of IgE molecules (antigens) as those immobilized on CPG without the spacer arm.