Polymer-inclusion complexes (PICs) with cyclodextrins (CDs) show a broad structural variety [1][2][3][4] and are of interest for many different applications, for example, drug delivery systems [5] and stimuli-responsive hydrogels. [6, 7] We have demonstrated that the lower critical solution temperature (LCST) of N-isopropylacrylamide(NIPAAM)-based copolymers bearing adamantyl groups can be influenced through complexation of the adamantyl moieties by cyclodextrins (CDs). [8,9] Recently, we reported on the synthesis of a PIC consisting of randomly methylated b-CD and a polymethacrylamide which showed a reversible phase transition in aqueous solution as a result of a dissociation/ complexation process.[10] Unfortunately, this system was not optimal in terms of chemical stability and the guest moiety used. We report herein on the pseudo-LCST behavior of PICs consisting of poly(adamantylacrylamide)s and Me-b-CD. In contrast to the previously reported system, the newly synthesized polyacrylamides are expected to be much more stable against hydrolysis. Additionally, the incorporated adamantyl moieties are well suited for inclusion into b-CD. With this optimized system we will demonstrate the influence of spacer groups and concentration on the phase-transition process.It is known that Me-b-CD-complexed hydrophobic monomers can be polymerized in water by means of a free-radical mechanism by use of water-soluble azo or redox initiators. [11] In most cases, the Me-b-CDs slip off the growing macroradicals which leads to precipitation of the polymeric material. In contrast, polymerization of Me-b-CD-complexed 1-adamantylacrylamide (1 a) and 6-acryloylaminohexanoic acid 1-adamantylamide (3 a) resulting the formation of the water-soluble polymer/Me-b-CD-complexes 2 a and 4 a, respectively (Scheme 1). The polymerization was carried out in water at 25 8C using 1 mol % of the redox initiator system K 2 S 2 O 8 /Na 2 S 2 O 5 .The molecular weights of the purified Me-b-CD-free polymers 2 and 4 were determined by MALDI-TOF mass spectrometry (Figure 1). Interestingly, the obtained polymer/ Me-b-CD complexes 2 a and 4 a show thermosensitive solubility properties in water that strongly depend on the distance between the Me-b-CD-complexed adamantyl groups and the polymer backbone. Figure 2 shows the transmittance of an aqueous solution of 2 a as a function of temperature. The measurement was performed at a concentration of 100 g L À1 using a heating/ cooling rate of 1 K min À1 . It can be seen that in the heating run the transmittance of the solution drops from 100 to 0 % within a temperature range of about 1-2 8C around the cloud point of 44.6 8C. This effect is caused by the dissociation of the polymer/Me-b-CD complex 2 a and the precipitation of the uncomplexed, more hydrophobic polymer; the Me-b-CD molecules remain in the aqueous solution. During the cooling run the transmittance did not return back to the starting level. However, after the solution had been stirred for several days at 5 8C, it became transparent again, indicating...

Summary: Various (meth)acrylamides were synthesized in good yields directly from (meth)acrylic acid and an amine using microwave irradiation in a solvent‐free environment. Under the applied conditions the (meth)acrylic function is preserved. Furthermore, the addition of an initiator like 2,2′‐azoisobutyronitrile (AIBN) to the starting mixture leads directly to poly(meth)acrylamides in a single step.

Human marrow was obtained as material discarded during total hip replacement and was established in culture with phenol red-free alpha-MEM with 10% fetal bovine serum (FBS) and antibiotics. Insulin-like growth factor I (IGF-I) and its binding proteins were secreted by human marrow cells, in amounts that increased with time in culture. Western ligand blotting showed that insulin-like growth factor binding protein-3 (IGFBP-3) accounted for the majority (approximately 75%) of the secreted binding proteins. Evidence for marrow secretion of BP-3 protease was found by electrophoretic analysis of mixtures of radiolabeled IGFBP-3 and marrow-conditioned media. The amount of constitutive secretion of IGFBP-3 increased with age of the subject (r = 0.97, p = 0.0058). A notable exception was marrow from a postmenopausal women on estrogen replacement therapy (ERT) at the time of surgery; her marrow secreted 89.3 ng/mL after 14 d in vitro, only 38% of the IGFBP-3 that was secreted by cultures from two age-matched peers (208.8 and 285.2 ng/mL). This in vivo effect of estrogen was matched by an in vitro experiment in which 10(-8) M 17-beta estradiol suppressed IGFBP-3 to 60% of the constitutive level. In all cultures of marrow from postmenopausal women, IL-1 beta suppressed IGFBP-3 secretion to either undetectable levels or levels between 11% and 35% of control. Thus, human bone marrow cultures demonstrate components of the skeletal IGF regulatory system: IGF-I, IGF-binding proteins, and evidence of IGFBP-3 proteolysis. These results provide evidence of regulation by both systemic (age, estrogen status) and cytokine (IL-1 beta) factors.

Summary: N‐methacryloyl‐1‐aminopropane (1), N‐methacryloyl‐1‐aminobutane (2), N‐methacryloyl‐1‐aminopentane (3), and N‐methacryloyl‐1‐aminohexane (4) are synthesized and treated with an aqueous solution of randomly methylated β‐cyclodextrin (Me‐β‐CD) to form the water‐soluble host‐guest complexes 1a–4a. In case of the aqueous polymerization of the free monomers 1–4 the initial polymerization rate increases with increasing water solubility. The opposite effect is observed in the case of the polymerizations of the Me‐β‐CD‐complexed methacrylamide monomers 1a–4a. The polymerization rates are increased with increasing alkyl chain length of the complexed monomers 1a–4a and decreasing water solubility of the free monomers 1–4.

N‐Adamantylacrylamide (3) was complexed with randomly methylated β‐cyclodextrin (RAMEB) forming the water‐soluble host–guest monomer‐complex 3a. A 1:1 complex stoichiometry was proven by NMR titration (Job's method). We investigated the free radical polymerization of the complex 3a using the water‐soluble azoinitiator 2,2′‐azobis[2‐(2‐imidazolin‐2‐yl)‐propane]dihydrochloride (VA044) at different temperatures. We observed that, below Tcrit a solution polymerization of 3a takes place. Above Tcrit, a precipitation mechanism leads to an increase in the relative polymerization rate.magnified image