| 1. |
- Björses, Katarina, et al.
(författare)
-
In vitro and in vivo evaluation of chemically modified degradable starch microspheres for topical haemostasis
- 2011
-
Ingår i: ACTA BIOMATERIALIA. - : Elsevier Science B.V. Amsterdam. - 1742-7061 .- 1878-7568. ; 7:6, s. 2558-2565
-
Tidskriftsartikel (refereegranskat)abstract
- Degradable starch microspheres (DSMs) are starch chains cross-linked with epichlorhydrin, forming glycerol-ether links. DSMs have been used for many years for temporary vascular occlusion and drug delivery in treatment of malignancies. They are also approved and used for topical haemostasis by absorbing excess fluid from the blood and concentrating endogenous coagulation factors, thereby facilitating haemostasis. This mechanism of action is not sufficient for larger bleedings in current chemical formulations of DSMs, and modification of DSMs to trigger activation of platelets or coagulation would be required for use in such applications. Chemical modifications of DSMs with N-octenyl succinic anhydride, chloroacetic acid, acetic anhydride, diethylaminoethyl chloride and ellagic acid were performed and evaluated in vitro with thrombin generation and platelet adhesion tests, and in vivo using an experimental renal bleeding model in rat. DSMs modified to activate platelets in vitro were superior in haemostatic capacity in vivo. Further studies with non-toxic substances are warranted to confirm these results and develop the DSM as a more effective topical haemostatic agent.
|
|
| 2. |
- Carlstedt, Jonas, et al.
(författare)
-
Hydration and the phase diagram of acid hydrolyzed potato starch
- 2014
-
Ingår i: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 112, s. 569-577
-
Tidskriftsartikel (refereegranskat)abstract
- We investigated hydration of acid hydrolyzed potato starch (maltodextrin) employing a multi-method approach. In particular, synchrotron radiation X-ray scattering and differential scanning calorimetry were used, and, for the first time, the material was investigated with sorption calorimetry and a newly developed quartz crystal microbalance with humidity scanning. The dry starch was found to be in an amorphous state. During hydration it exhibits a glass transition in both bulk and thin film samples, followed by an exothermic event where the starch crystallized. Recrystallized bulk samples displayed neither a pronounced glass transition nor crystallization upon hydration whereas both events occurred in thin film samples. The hydration-driven crystallization resulted in an X-ray pattern consistent with the coexistence of A and B type crystallites; however, at higher water concentrations only the B form occurred. The results were used to construct the first ever acid hydrolyzed starch–water phase diagram.
|
|
| 3. |
- Carlstedt, Jonas, et al.
(författare)
-
Understanding Starch Gelatinization : the Phase Diagram Approach
- 2015
-
Ingår i: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 129, s. 62-69
-
Tidskriftsartikel (refereegranskat)abstract
- By constructing a detailed phase diagram for the potato starch–water system based on data from optical microscopy, synchrotron X-ray scattering and differential scanning calorimetry, we show that gelatinization can be interpreted in analogy with a eutectic transition. The phase rule explains why the temperature of the gelatinization transition (G) is independent on water content. Furthermore, the melting (M1) endotherm observed in DSC represents a liquidus line; the temperature for this event increases with increasing starch concentration. Both the lamellar spacing and the inter-helix distance were observed to decrease with increasing starch content for starch concentrations between approximately 65 wt% and 75 wt%, while the inter-helix distance continued decreasing upon further dehydration. Understanding starch gelatinization has been a longstanding challenge. The novel approach presented here shows interpretation of this phenomenon from a phase equilibria perspective.
|
|
| 4. |
|
|
| 5. |
|
|
| 6. |
- Wojtasz, Joanna, et al.
(författare)
-
Hydration and swelling of amorphous cross-linked starch microspheres
- 2016
-
Ingår i: Carbohydrate Polymers. - : Elsevier. - 0144-8617 .- 1879-1344. ; 135, s. 225-233
-
Tidskriftsartikel (refereegranskat)abstract
- Hydration of cross-linked starch microspheres, commercially available as a medical device, was investigated using a multi-method approach. We found that the uptake of water is accompanied by substantial swelling and changes of the polymer structure. Sorption calorimetry provided information about thermodynamics of water sorption, revealed presence of isothermal glass transition and absence of hydration-induced crystallization, observed in non-cross linked starch material. The changes in the surface and bulk properties of microspheres at different water–starch concentrations were investigated using synchrotron radiation X-ray scattering and analyzed using concept of fractals. The obtained information, combined with the results of differential scanning calorimetry, was used to construct a phase diagram of the studied material. Finally, hydration induced evolution of polymer structure revealed by the X-ray scattering was linked to the changes observed during swelling with optical microscopy.
|
|
