ABSTRACT
The degradability improvement of poly(ethylene terephthalate) (PET), one of the most widely used but non-degradable disposable packaging material, is of great significance. However, the balance between degradability and mechanical properties remains a huge challenge. Herein, simple hydroxy acids, lactic acid (LA) and glycolic acid (GA) as easy hydrolysis sites were introduced into non-degradable PET via melt polycondensation. A series of high molecular weight poly(ethylene terephthalate-co-Llactide) (PETL) and poly(ethylene terephthalate-co-glycolate) (PETG) copolyesters were synthesized with an excellent tensile strength greater than 50 MPa, much higher than that of most commercially available degradable polymers. The introduction of hydroxy acid endows PET with significantly improved composting and seawater degradation performance. Furtherly, the degradation rate of PETG with hydrophilic GA unit was faster than that of PETL, and the mineralization rate of PETG80 reaches 22.0%. The density of functional theory (DFT) calculation revealed that adding hydroxy acid to the PET molecular chain reduced the energy barrier of the hydrolysis reaction. The molecular polarity index (MPI) analysis furtherly confirmed that the higher affinity between the GA unit and water may be the primary reason for the faster degradation of PETG.
ABSTRACT
RATIONALE: In addition to axillary lymph node (ALN), internal mammary lymph node (IMLN) is also the first-echelon drainage nodes reached by metastasising cancer cells from breast cancer, which can provide important prognostic information. PATIENT CONCERNS: In this paper, we will introduce a case of breast cancer patient whose postoperative pathology result showed that she had internal mammary sentinel lymph node (IMSLN) metastases but no axillary sentinel lymph node (ASLN) metastases. DIAGNOSES: She was diagnosed as pT1cN1bM0 breast cancer based on the positive IMSLN but negative ASLN. INTERVENTIONS: She received axillary-sentinel lymph node biopsy (A-SLNB) and internal mammary-sentinel lymph node biopsy (IM-SLNB) guided by modified injection technique. In the choice of chemotherapy, she received dose-dense ACâ×â4 times followed Pâ×â4 times for chemotherapy. As to irradiation therapy, she received irradiation therapy include chest wall, superclavicular region, and internal mammary nodes. OUTCOMES: After performing IM-SLNB, the nodal staging of this patient increased (from N0 to N1b). And she received additional chemotherapy and irradiation therapy. LESSONS: With the guidance of modified injection technique, the preoperative visualization rate of IMLN has been improved. IM-SLNB could be a minimally invasive technique for effective evaluation of the status of IMLN to provide information for staging and guide the adjuvant treatment.
