PubMed · 15815736
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Lars Slørdal, Olav Spigset. 2005-04-07. [Basic pharmacokinetics--absorption].. https://pubmed.ncbi.nlm.nih.gov/15815736/
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Hydrogen-bonded networks composed of guanidinium (G) and 1,5-naphthalenedisulfonate (NDS) have been developed for the selective inclusion and separation of fatty acid esters based on their degree of unsaturation. Porous crystalline networks have been synthesized and include fatty acid esters during crystallization from both methanol and 2-methoxyethanol. Crystalline networks formed in methanol are selective for the inclusion of saturates in preference to polyunsaturated fatty acid methyl esters, but their applicability is limited by the competing inclusion of the solvent methanol. In 2-methoxyethanol, a three-component host structure is formed that provides 4.1 x 4.7 A2 pores which are also selective for saturated fatty acid ester inclusion. These networks do not suffer from the competing inclusion of the solvent 2-methoxyethanol as is the case with methanol, and thus complete removal of initial saturated fatty acid 2-methoxyethyl esters is possible. Binary selectivity experiments on mixtures of the 2-methoxyethyl esters of saturated stearic acid and the omega-3 fatty acid alpha-linolenic acid reveal that this three-component network structure provides nearly complete resolution of these two guests in the crystal and filtrate fractions. Separation of the 2-methoxyethyl esters of alpha-linolenic acid from the monounsaturated oleic acid is also possible, although with decreased efficiency in comparison to removal of the saturated fatty acid ester.
The lifetimes of benzophenone in the higher triplet excited state (BP(T(n))) and several BP derivatives in the T(n) states were measured directly to be tau(T(n))=37+/-7 ps and 20-33 ps, respectively, by using the nanosecond-picosecond (ns-ps) two-color/two-laser flash photolysis method. Based on the direct measurements of tau(T(n)) of BP(T(n)), the triplet energy transfer (TET) from BP(T(n)) to quenchers (Q), such as carbon tetrachloride (CCl4), benzene (Bz), and p-dichlorbenzene (DCB), was investigated. The fast TET from BP(T(n)) to Q can be attributed to the lifetime-dependent quenching process, according to the Ware theoretical model of the bimolecular energy transfer reaction. The contribution of the lifetime-dependent term on k(TET) was 27, 60, and 86% for CCl4, Bz, and DCB as the Q of BP(T(n)), respectively, indicating that the TET from BP(T(n)) to Q is influenced not only by tau(T(n)), but also by the size of Q.
In this study, we first investigated the in vitro degradation properties of biodegradable, bioresorbable polycaprolactone-20% tricalcium phosphate (PCL-TCP) composites immersed in simulated body fluid (SBF) and phosphate buffered saline (PBS). Then, the release profiles of the growth factors present in platelet-rich plasma (PRP) loaded onto the composites incubated in SBF and PBS were compared. Composites immersed in both buffers showed water uptake of 13.7%+/-0.75 at day 1, followed by a constant uptake of 12.1%+/-0.3 until day 12. Henceforth the water uptake declined for SBF- and increased for PBS-soaked composites. The weight loss data did not reveal any trend. SBF- and PBS-soaked samples displayed 1-2% weight loss for 2 and 5 of the ten time points measured respectively. The original protein retention (PR) of the composites was 49.1%+/-1.50. After immersion in SBF and PBS for 4 weeks, the PR was augmented to 88.5%+/-1.40 and 69.1%+/-1.40 correspondingly. PRP after activation contained 164.7+/-24.8, 194+/-43 and 18.3+/-4.75 ng/ml of TGF-beta1, PDGF-BB and IGF-1. Microscopic analysis verified the attachment of PRP to the rods and pores of the composites. Interestingly, the buffers played an important role in determining the release profiles of TGF and PDGF. Firstly, PBS-soaked composites manifested a tri-phasic burst-like profile that was absent in SBF. Secondly, SBF-soaked composites experienced delayed release of the growth factors and total release was not achieved (64.4% for TGF and 60.5% for PDGF), whereas total release was realized for PBS-soaked composites. Lastly, release profiles from SBF-soaked composites were growth factor mediated in terms of their amounts and sizes. This was not observed for PBS-soaked composites. IGF-1, on the other hand, exhibited a progressive reduction in levels over the entire experimental period for both buffers. The mechanisms of release were theorized to be a combination of diffusion, degradation and bioactivity. Since SBF is analogous to our body fluids in terms of its ionic constituents, we expect the elution profiles derived from SBF-soaked samples to more accurately emulate the in vivo situation. In conclusion, this study has deemed PCL-TCP composites as suitable delivery systems for platelet-rich plasma.