Medical adsorbents

Hexamethylene diisocyanate (HDI) is used in the preparation of dental materials, medical adsorbents, and contact lenses, and is used as a polymerizing agent in polyurethane paints and coatings. 

ACFs have been successfully applied in many fields, such as the treatment of organic and inorganic waste gases, the recovery of organic solvent, air cleaning and deodorization, treatment of wastewater and drinking water, separation and recovery of precious metals, as medical adsorbents and protective articles, and in electrodes [57], Some of the most common applications of ACF are listed below Table 8.2. 

In terms of membrane area used and doUar value of the membrane produced, artificial kidneys are the single largest appHcation of membranes. Similar hoUow-fiber devices are being explored for other medical uses, including an artificial pancreas, in which islets of Langerhans supply insulin to diabetic patients, or an artificial Uver, in which adsorbent materials remove bUinibin and other toxins. 

The isotope molybdenum-99 is produced in large quantity as the precursor to technetium-99y, a radionucleide used in numerous medical imaging procedures such as those of bone and the heart (see Medical imaging technology). The molybdenum-99 is either recovered from the fission of uranium or made from lighter Mo isotopes by neutron capture. Typically, a Mo-99 cow consists of MoO adsorbed on a lead-shielded alumina column. The TcO formed upon the decay of Mo-99 by P-decay, = 66 h, has less affinity for the column and is eluted or milked and either used directly or appropriately chemically derivatized for the particular diagnostic test (100). 

ANTIFLATULENTS. Activated charcoal can adsorb drugs while they are in the GI tract. The nurse administers charcoal 2 hours before or 1 hour after other medications. If diarrhea persists or lasts longer than 2 days or is accompanied by fever, the nurse notifies the primary care provider. Simethicone is administered after each meal and at bedtime... 

Attapulgite adsorbs excess fluid in the stool with few adverse effects. Calcium polycarbophil is a hydrophilic polyacrylic resin that also works as an adsorbent, binding about 60 times its weight in water and leading to the formation of a gel that enhances stool formation. Neither attapulgite nor polycarbophil is systemically absorbed. Both products are effective in reducing fluid in the stool but can also adsorb nutrients and other medications. Their administration should be separated from other oral medications by 2 to 3 hours. Psyllium and methylcellulose products may also be used to reduce fluid in the stool and relieve chronic diarrhea. 

Urokinase utilized medically is generally purified directly from human urine. It binds to a range of adsorbents, such as silica gel and, especially, kaolin (hydrated aluminium silicate), which can be used initially to concentrate and partially purify the product. It may also be concentrated and partially purified by precipitation using sodium chloride, ammonium sulfate or ethanol as precipi-tants. 

Knowledge of the surface structure of CaHAP panicles is fundamentally needed not only in medical and dental sciences but also in application of synthetic CaHAP particles to bioceramics and adsorbents for biomaterials, because the affinity of CaHAP surface to biomaterials is an important factor in all the cases. The surface structure of CaHAP was investigated by various means including infrared (IR) (38,39), NMR (40). TPD (41), and XPS (42). Among these methods, IR spectroscopy is most appropriate for the surface characterization of CaHAP particles. 

Activated carbons are widely used for treatment of acute and chronic poisoning as oral adsorbents and for blood purification. However, medical carbons currently available are predominantly microporous and their use is therefore limited to... 

The activated carbons obtained have a potential for medical applications in treatment of chemical and biological poisoning as oral adsorbents and in extracorporeal blood detoxication. 

For evaluation of efficiency of medical sorbents, the issue of their deliganding properties, i.e. an ability to withdraw toxic protein bound compounds (ligands) is of great importance. If a sorbent possesses strong deliganding capability as, for example, some types of modem carbon hemosorbents do [11,12], then after contact with such an adsorbent, the ratio of molar concentrations of ligand - protein carrier (M /Mp) decreases, i.e. the transport protein transforms into a more purified state than it was initially (Table 21.3). 

---