BACKGROUND:Shape memory polymer is a new type of functional material. The applications of shape memory polymers in the biomedical field have increasingly been paid close attention. OBJECTIVE: To summarize the characteristics and applications of shape memory polymers. METHODS: SpringerLink and China Journal Ful text Database were searched for articles related to shape memory polymers. RESULTS AND CONCLUSION: As a new type of inteligence material, shape memory polymers have lots of advantages compared with shape memory aloy and shape memory ceramics, such as low density, light weight, low cost, high shape-recovery rate, easy to regulate the shape memory temperature, to dye, to shape and to be stimulated under expected switch temperature. Especialy for polyurethane, the structure-property relationships are extremely easy to control, the shape memory temperature can be set in a wide range from-30℃ to 70℃, and it has the biocompatibility. Due to these, shape memory polymers have great potentials in applications of biomedical engineering. But the comprehensive properties of the developed shape memory polymers are not satisfactory. For example, the polynorbornene has big recovery stress, fast recovery velocity and high recovery precision, but its relative molecular mass is very big, the molecularchain is long, and processing is difficult. Furthermore, most of shape memory polymers have smal recovery stress, slow recovery velocity, low recovery precision and unsatisfied repeat memory effect. The key problems for shape memory polymers include optimization of the function of shape memory and improvement of the comprehensive properties based on the technologies of molecular design and material modification.

Objective To evaluate the efficacy of chemoradiotherapy in patients with unresectable pancreatic cancer who were previously treated with PTCD.Methods From September 2005 to December 2012,47 unresectable pancreatic cancer patients with obstructive jaundice were enrolled in this study.They were divided into two groups.21 patients received after PTCD chemotherapy or radiation,or chemoradiotherapy.26 patients in support care group received only nutrition,analgesia and other related support treatment.Survival analysis was performed with Kaplan-Meier statistics.Differences in survival between the groups were assessed for statistical significance with the log-rank test.Results The median overall survival time of patients after PTCD was 7.19 months.The median overall survival time of chemoradiation group was 9.07 months,which was higher than that of support care group (5.52 months),P=0.017.12 patients received single therapy (either chemo or radiation),and 9 patients received chemoradiotherapy.The median overall survival times were 8.31 months and 11.15 months,respectively (P =0.325).Conclusions Post PTCD chemoradiotherapy helps prolong the survival time in unresectable pancreatic cancer patients.

Objective To study the efficacy of CPT-11 TACE in the treatment of unresectable HCC.Methods A retrospective review was undertaken on unresectable HCC patients receiving doxorubicin transarterial chemoembolization (59 cases) and irinotecan(CPT-11) in 24 cases from May 2003 to November 2011.Survival analysis was performed with Kaplan-Meier statistics.Differences in survival between the two groups were assessed for statistical significance with the log-rank test.Results Overall survival time was significantly longer in patients treated with CPT-11 compared with doxorubicin treated group (21.7 vs 14.5 months,P =0.042).There was no significant difference in time to progression between the two groups,but time to progression was longer in CPT-11 group than doxorubicin treated group (11.42 vs 9.46 months,P =0.091).Subgroup analysis showed that for intermediate-stage HCC,CPT-11 resulted in a significantly longer time to progression and overall survival compared with doxorubicin treated group (P =0.029 and P =0.014,respectively).There were no significant differences in adverse events among the two groups (P ＞ 0.05).Conclusions Chemotherapeutic agent CPT-11 in the form of TACE significantly improved overall survival when compared with doxorubicin for the treatment of unresectable HCC.