Synthesis and Properties of Targeted Radioisotope Carriers Based on Poly(Acrylic Acid) Nanogels

Radiation crosslinking was employed to obtain nanocarriers based on poly(acrylic acid)—PAA—for targeted delivery of radioactive isotopes. These nanocarriers are internally crosslinked hydrophilic macromolecules—nanogels—bearing carboxylic groups to facilitate functionalization. PAA nanogels were conjugated with an engineered bombesin-derivative—oligopeptide combined with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate chelating moiety, aimed to provide selective radioligand transport. 4-(4,6-Dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium (DMTMM) toluene-4-sulfonate was used as the coupling agent. After tests on a model amine—p-toluidine—both commercial and home-synthesized DOTA-bombesin were successfully coupled to the nanogels and the obtained products were characterized. The radiolabeling efficiency of nanocarriers with 177Lu, was chromatographically tested. The results provide a proof of concept for the synthesis of radiation-synthesized nanogel-based radioisotope nanocarriers for theranostic applications.

Radiation-crosslinked scaffolds from gelatin/CM-chitin and gelatin/CM-chitosan hydrogels for adipose-derived stem cell culture

Radiation technology has been providing a useful tool to modify polymers involving the radiation crosslinking of hydrogels. In the present work, two kinds of hydrogels composed gelatin and carboxymethyl chitosan (gelatin/CM-chitosan), and carboxymethyl chitin (gelatin/CM-chitin) were prepared by the radiation crosslinking. The resulting hydrogels were freeze-dried, sterilized under gamma-ray at a sterilization dose of 25 kGy, and characterized to be utilized as the scaffolds for culturing adipose-derived stem cells (hADSCs). The physicochemical properties, biodegradability, and cytotoxicity of these scaffolds were also investigated. The results indicated that both CM-chitosan and CM-chitin much improved the swelling capacity, porosity, and pore size of the gelatin-derived scaffolds. The swelling degree of gelatin/CM-chitosan and gelatin/CM-chitin scaffolds was about 7-9 g/g after 6 hrs immerging in PBS, and their porosity was about 70-73% with pore size ranging from 100 to 300 mm. The results also revealed that the compressive modulus of gelatin/CM-chitosan and gelatin/CM-chitin was 45.6 and 66.4 kPa, respectively, which were suitable for soft tissue engineering. Both scaffolds were enzymatically biodegradable by collagenase and non-cytotoxic for hADSCs with an RGR of ~97%. Thus, the resultant scaffolds can be suitably utilized for culturing hADSC in practice to regenerate soft tissues.

Influence of Solid TAIC on Crosslinking LLDPE by Electron Beam Radiation

In this work, solid triallyl isocyanurate (TAIC) has been fabricated and used as the crosslinking sensitizer for linear low density polyethylene (LLDPE) crosslinking application. First, 0 phr, 1.5 phr, 3.0 phr, 4.5 phr and 6.0 phr solid TAIC have been added into the LLDPE to study the radiation crosslinking results. The resulting samples are measured by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), etc. The results reveal that the crystallinity, melt point, elongation and volume resistivity decrease when the content of solid TAIC increases in LLDPE from 0 phr to 6.0 phr. However, adding a proper amount of solid TAIC (3.0 phr) can improve the crosslinking degree and tensile strength of LLDPE. Finally, the space charge distribution of the samples has been measured, and the possible mechanism of solid TAIC that affects the LLDPE electrical properties is proposed.

Effect of Radiation Crosslinking and Surface Modification of Cellulose Fibers on Properties and Characterization of Biopolymer Composites

Recently, polymers have become the fastest growing and most widely used material in a huge number of applications in almost all areas of industry. In addition to standard polymer composites with synthetic matrices, biopolymer composites based on PLA and PHB matrices filled with fibers of plant origin are now increasingly being used in selected advanced industrial applications. The article deals with the evaluation of the influence and effect of the type of surface modification of cellulose fibers using physical methods (low-temperature plasma and ozone application) and chemical methods (acetylation) on the final properties of biopolymer composites. In addition to the surface modification of natural fibers, an additional modification of biocomposite structural systems by radiation crosslinking using gamma radiation was also used. The components of the biopolymer composite were a matrix of PLA and PHBV and the filler was natural cellulose fibers in a constant percentage volume of 20%. Test specimens were made from compounds of prepared biopolymer structures, on which selected tests had been performed to evaluate the properties and mechanical characterization of biopolymer composites. Electron microscopy was used to evaluate the failure and characterization of fracture surfaces of biocomposites.