A model is developed in the form of one or two partial differential equations (master Smoluchowski-like equations) that describe evolution of the size distribution of polymer species formed in a step-growth polymerization of an AB 2 monomer. Groups B react with a substitution effect; i.e., they are initially equally reactive, but the reactivity of the second B group changes as the first has reacted. One master equation is sufficient to model formation of branched molecules only. Two are needed to take into account intramolecular cyclization. Monte Carlo simulations of the same process are used to verify the results of applying the kinetic model. The model can be applied to calculate various molecular parameters in polymerizing systems, including various average degrees of polymerization, size distribution of acyclic and cycle-containing polymer molecules, degree of branching, etc. Explicit formulas describing the dependence of some of these quantities on time or conversion degree are derived for the random system, i.e., the system reacting without substitution effect.

Two new rigid bi-aromatic linkers for synthesis of peptide arrays by SPOT methodology were obtained from cellulose treated with 2,4-dichloro-6-methoxy-1,3,5-triazine. Reaction with m-phenylenediamine gave non-cleavable TYPE I linker which enabled attachment of the peptides via resistant to harsh reaction conditions amide, ether, and amine bonds. Reaction with 3-Fmoc-aminobenzoic acid followed by thermal isomerization of the intermediate "superactive" ester producing an amide-like bond gave TYPE II linker that was very stable during peptide synthesis. However, the peptide was cleavable, with fragment of the linker, in the presence of 1 M LiOH solution. The uniform loading of the cellulose and efficient synthesis of the peptide array was achieved by using N-(4,6-dimethoxy-1,3,5-triazin-1-yl)-N-methylmorpholinium 4-toluenesulfonate as the coupling reagent.

A kinetic model of hyperbranched polymerization is presented where an AB2 monomer reacts with up to 10% of a B3 one (A and B are functional groups) to yield a hyperbranched polymer. The model consists of two compact rate equations for entire distributions of two kinds of molecules that are formed in the system. Changes in reactivity of B groups in the form of the so-called first shell substitution effect are taken into account. Molecular parameters, namely the number and weight averages of polymerization degree as well as the average degree of branching of hyperbranched molecules, are extracted out from the rate equations and plotted against conversion.

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Polyurethane (PU) elastomers were synthesized by the reaction of HDI or IPDI diisocyanates and poly(ε-caprolactone) (PCL or poly(ethylene adipate) (PA) diols and ethylene glycol as a polymer chain extender. IR, 1H, and 13C NMR spectroscopy and X-ray analysis were used for the structural analysis of the formed films. The molecular weight distribution was examined by GPC chromatography. Based on the measured contact angles, free surface energy parameters were calculated. The obtained results were analyzed for the possible use of these polyurethanes as biomaterials. The most promising in this respect was PU-3, which was synthesized from IPDI and PCL. This was due to its high molecular weight of approximately 90,000, the presence of a crystalline phase, and the relatively high hydrophobicity, with a SEP value below 25 mJ/m2. These films showed a good resistance to hydrolysis during incubation in Baxter physiological saline during 6 weeks. Both Gram-positive (Bacillus sp.) and Gram-negative (Pseudomonas sp.) types of bacterial strains were used to test the biodegradation property. Synthesized PUs are biodegradable and showed moderate or even mild cytotoxicity against human normal fibroblasts (BJ) and immortalized keratinocytes (HaCaT), estimated with direct contact assay. The most biocompatible was PU-3 film, which revealed rather mild reactivity against both cell lines, and the least was PU-2 film, synthesized from HDI and PA (severe toxicity for HaCaTs).

A theoretical model of hyperbranched polymerization involving an AB f monomer Part II. THE AVERAGE POLYMERIZATION DEGREE AND DISPERSITY INDEX * *) Summary-A generalized theoretical model of hyperbranched polymerization of an AB f monomer was used to calculate the weight average polymerization degree (P w) and dispersity index (D M) of the resulting hyperbranched polymers. The monomer functionalities were f = 2, 4, or 6. The model derived in Part I of the series and based on the Smoluchowski coagulation equation was used. The monomer functional groups B reacted according to the first shell substitution effect principle. Both, the weight average polymerization degree and dispersity index were found to grow with conversion the faster, the higher was the monomer functionality and the more positive was the substitution effect.

Polyhydroxylated dendrimer was synthesized from poly(amidoamine) (PAMAM) dendrimer generation 3 by addition of glycidol (G3gl). G3gl megamer was further modified by binding PAMAM G0 dendrimers by activation of G3gl with p-nitrophenylchloroformate, followed by the addition of excess PAMAM G0 and purification using dialysis. The maximum G0 binding capacity of G3gl was 12 in the case when G0 was equipped with two covalently attached nimesulide equivalents. Nimesulide (N) was converted into N-(p-nitrophenyl) carbonate derivative and fully characterized using X-ray crystallography and spectral methods. Nimesulide was then attached to G0 via a urea bond to yield G02N. The mixed generation G3gl–G02N megamer was characterized using 1H NMR spectroscopy, and its molecular weight was estimated to be 22.4 kDa. The AFM image of G3gl–G02N deposited on mica demonstrated aggregation of nimesulide-covered megamer. The height of the deposited megamer was 8.5 nm. The megameric conjugate with nimesulide was tested in vitro on three human cell lines: squamous cell carcinoma (SCC-15) and glioblastoma (U-118 MG) overexpressing cyclooxygenase-2 (COX-2), and normal skin fibroblasts (BJ). The conjugate efficiently penetrated into all cells and was more cytotoxic against SCC-15 than against BJ. Moreover, the conjugate produced a strong and selective antiproliferative effect on both cancer cell lines (IC50 < 7.5 µM).

Third-generation poly(amidoamine) dendrimer (PAMAM) was modified by stepwise primary amine group amidation with d-glucoheptono-1,4-lactone. The physicochemical properties of the conjugates—size, ζ potential in lysosomal pH 5 and in neutral aqueous solutions, as well as intramolecular dynamics by differential scanning calorimetry—were determined. Internalization and toxicity of the conjugates against normal human fibroblasts BJ were monitored in vitro in order to select an appropriate carrier for a drug delivery system. It was found that initial glucoheptoamidation (up to 1/3 of amine groups of neat dendrimers available) resulted in increase of conjugate size and ζ potential. Native or low substituted dendrimer conjugates accumulated efficiently in fibroblast cells at nontoxic 1 µM concentration. Further substitution of dendrimer caused consistent decrease of size and ζ potential, cell accumulation, and toxicity. All dendrimers are amorphous at 36.6 °C as determined by differential scanning calorimetry (DSC). The optimized dendrimer, half-filled with glucoheptoamide substituents, was applied as carrier bearing two covalently attached cytisine molecules: a rigid and hydrophobic alkaloid. The conjugate with 2 cytisine and 16 glucoheptoamide substituents showed fast accumulation and no toxicity up to 200 µM concentration. The half-glucoheptoamidated PAMAM dendrimer was selected as a promising anticancer drug carrier for further applications.