Polymers in medicine

Palliation therapy for dysphagia using esophageal stents is the current treatment of choice for those patients with inoperable esophageal malignancies. However, the stents currently used in the clinical setting, regardless of the type of metal mesh or plastic mesh stents (covered/uncovered), may cause complications, such as tumor ingrowth and stent migration into the stomach. Furthermore, metal mesh stents have limited capacities for loading anti-cancer drugs. To effectively reduce/overcome those complications and enhance the efficacy of drug release, we designed and 3D-printed a tubular, flexible polymer stent with spirals, and then load anti-cancer drug, paclitaxel, on the stent for drug release. Non- spiral 3D-printed tubular and mesh polymer stents served as controls. The self-expansion and anti migration properties, cytotoxicity, drug release profile, and cancer cell inhibition of the 3D-printed stent were fully characterized. Results showed the self-expansion force of the 3D-printed polymer stent with spirals was slightly higher than the stent without spirals. The anti-migration force of the 3D-printed stent with spirals was significantly higher than the anti-migration force of a non-spiral stent. Furthermore, the stent with spirals significantly decreased the migration distance compared to the migration distance of the non-spiral 3D-printed polymer stent. The in vitro cytotoxicity of the new stent was examined through the viability test of human esophagus epithelial cells, and results indicated that the polymer stent does not have any cytotoxicity. The results of in vitro cell viability of esophageal cancer cells further indicated that the paclitaxel in the spiral stent treated esophageal cancer cells much more efficiently than that in the mesh stent. Furthermore, the results of the in vitro drug release profile and drug permeation showed that the dense tubular drug-loaded stent could efficiently be delivered more paclitaxel through the esophageal mucosa/submucosa layers in a unidirectional way than mesh stent that delivered less paclitaxel to the esophageal mucosa/submucosa but more to the lumen. In summary, these results showed that the 3D-printed dense polymer stent with spirals has promising potential to treat esophageal malignancies.

A large number of metal-containing compounds show significant activity against cancer cells and incorporating a metal into a polymer offers several possible advantages. Compounds of the type R2SnCl2 (R = methyl, ethyl, propyl, butyl, t-butyl, octyl and phenyl) were tested for the ability to inhibit the growth of Balb 3T3 mouse fibroblast cells and CAOV3 human ovarian carcinoma cells. Polymers of 2-chloro-1,4-benzenediamine and the same organotin dichloride were synthesized and tested as well. For both monomers and polymers, the pattern of growth inhibition relative to the R group was butyl > propyl = t-butyl = octyl = phenyl > ethyl > methyl. This and other aspects of the structure-activity relationship of the monomers and polymers were examined.

Cancer is the second leading cause of death in the western world. In order to treat various types of cancer, platinum-based drugs are most widely employed as metal-containing chemotherapeutic agents. However, their clinical usage is hindered by toxic side effects, and by the emergence of drug resistance. Our focus was to replace platinum with less toxic metal like tin which can give better alternatives for cancer treatment. The major aim of our study was to synthesize novel organotin polyethers (Sn-O) which can be used to combat cancer. Preliminary results from our laboratory using organotin polyethers, that were synthesized by varying the structure of diols showed growth inhibition in Balb-3T3 cells. This study directly led us to hypothesize the two structural windows, first by changing the distance between diol and second, by presence of unsaturation in diols, the biological activity of organotin polyethers (Sn-O) can be enhanced significantly. Different series of polymeric compounds were synthesized based upon these two structural windows and the formation of products was validated using standard techniques like infrared spectroscopy (IR), light scattering photometer, matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) and nuclear magnetic resonance (NMR). The synthesized polymers arrested the growth of cancer cell lines including bone, prostate, colon, breast, pancreas and lung cancer derived cell lines in vitro. In number of instances where chemotherapeutic index values of two and greater were found that these polymers are significantly more active against cancer cells than non-cancerous cells in culture.

The dental field shows proliferation in the market of new adhesives. The purpose of this study is to evaluate the mechanical properties on total restoration, based on the manufacturer's technical specifications, experimental and mechanical test results. The optimal dentist's selection will be when the most appropriate adhesive can be chosen for one specific restoration, avoiding wasted time, material and exposure to marginal infections with a failure restoration. This research was developed in stages. The first step is the study of the tooth morphological information. Following, there is the structure identification type and the chemical composition of six different pure adhesives. Next, perform the X-R Diffraction, Energy Disperse Spectroscopy (EDS), and Scanning Electron Microscopy (SEM). The final step is to perform the mechanical test, computer simulation, and discuss the results to obtain the best dental adhesive with and the new finding. Result: The samples show an amorphous structure and a chemical composition in the X-R Diffraction, SEM and EDS experiments. The mechanical test shows real mechanical properties under tension and sheer rupture stress. Poisson ratio, strain, and another relationship will be used in the computer simulation test. Results will be reflected in the Discussion and Conclusion. Significance: The first conclusion is that the amorphous structure is present in all six adhesives experiments. In addition, it shows strong possibilities of bonding with another neighbor's molecules. The discussion will be extended to the bonding advantages for this type of structure in the total dental restoration.