Specific interactions between cryogel components: role of extra domain A containing fibronectin in cryogelation

Bioadhesive interaction and hypoglycemic effect of insulin-loaded lectin–microparticle conjugates in oral insulin delivery system

Biodegradable microparticles were prepared with alginate by the piezoelectric ejection process, and lectin (wheat germ agglutinin, WGA) was conjugated to alginate microparticles to take advantage of the protective effects of alginate microparticles and the mucoadhesive properties of WGA for improved oral delivery of insulin. Their specific interaction with model mucin was determined by pig mucin (PM) immobilized surface plasmon resonance (SPR) biosensor and in vitro adsorption studies. The hypoglycemic effects of alginate and WGA-conjugated alginate microparticles were examined after oral administration in streptozotocin-induced diabetic rats. The alginate microparticles were fabricated by ejecting alginate/insulin solution into 0.1 M CaCl2 solution through a nozzle actuated by the piezoelectric transducer. The WGA was conjugated to alginate microparticles by activating hydroxyl groups with carbonyldiimidazole (CDI). The affinity constant (K(A)) of alginate-WGA microparticles from the SPR data (K(A)=5.455 g(-1) L) was about nine times greater than alginate microparticles (K(A)=0.628 g(-1) L). In vitro experiments in the mucin solution showed that the conjugated WGA enhanced the interaction about three times. In vivo studies with diabetic rats showed that the blood glucose level of SPF rats was lowest when alginate-WGA microparticles were orally administered. Larger K(A) of alginate-WGA microparticles resulted in larger glucose change (%) from base level. Still, it is not clear whether the transport of insulin through the intestinal mucous membrane was influenced by the increase of residence time at intestinal membrane through the specific adsorption of WGA-conjugated microparticles. However, it is concluded that alginate-WGA microparticles enhance the intestinal absorption of insulin sufficient to drop the glucose level of blood.

A survey of the year 2002 commercial optical biosensor literature

We have compiled 819 articles published in the year 2002 that involved commercial optical biosensor technology. The literature demonstrates that the technology's application continues to increase as biosensors are contributing to diverse scientific fields and are used to examine interactions ranging in size from small molecules to whole cells. Also, the variety of available commercial biosensor platforms is increasing and the expertise of users is improving. In this review, we use the literature to focus on the basic types of biosensor experiments, including kinetics, equilibrium analysis, solution competition, active concentration determination and screening. In addition, using examples of particularly well-performed analyses, we illustrate the high information content available in the primary response data and emphasize the impact of including figures in publications to support the results of biosensor analyses.

Inhibition of cryogelation by the novel synthetic peptide (Gly-Arg-Lys-Lys-Thr): recognition site of extra domain A containing fibronectin for heparin in cryogelation

Cryogel is a physical gel formed by the heterophilic aggregation of extra domain A (EDA) containing fibronectin [EDA(+)FN], plasma fibronectin (pFN), fibrinogen (Fbg) and heparin (Hep) in the blood of rheumatoid arthritis (RA) patients. In cryogelation EDA(+)FN cross-links to form an interaggregate of cryogel with Hep. In the present study, we determined the recognition structure of Hep for EDA(+)FN by using oligo- and desulfonated-Hep. The affinity constant (KA) (1.2 x 10(8) per M) of oligo-Hep for EDA(+)FN did not change with a decrease in number-average molecular weight (4.9 x 10(4)-->6.0 x 10(3)). The KA-value of desulfonated-Hep for EDA(+)FN decreased from 3.2 x 10(8) to 1.0 x 10(7) per M with a decrease in the sulfonation ratio (7.0-->4.3%). We also determined the recognition structure of EDA(+)FN for Hep by an inhibition experiment on the heparin binding domain II (HepII) in EDA(+)FN with the synthetic peptides, Arg-Arg-Ala-Arg (RRAR), Asp-Gln-Ala-Arg (DNAR), Ile-Lys-Tyr-Glu-Lys (IKYEK), and Gly-Arg-Lys-Lys-Try (GRKKT). The GRKKT sequence clearly inhibited bonding between EDA(+)FN and Heps containing oligo- and desulfonated-Hep. The amount of cryogel formed in the RA-patient model plasma corresponded to the EDA(+)FN concentration in cryogel (36.7%) normalized by the EDA(+)FN concentration in plasma. When GRKKT was added to plasma, the EDA(+)FN concentration fell to 10.5%. These results demonstrated that inhibition of cryogelation in plasma could progress to a novel treatment for RA.