A photothermal/chemotherapy injectable paclitaxel gel with irradiation stability / 生物医学工程学杂志

The aim of this study is to construct an injectable gel with stable phototherapy and chemotherapy. Res-PTX@IR780 gel with phototherapy and chemotherapy property was prepared by introduction of photosensitizer IR780 and antioxidant resveratrol (Res) into the polyethylene glycol (PEG) solution of paclitaxel (PTX). The results showed that PTX, PTX@IR780 and Res-PTX@IR780 could form gels and the gels were injectable. ATR-FTIR results indicated not only components of the gels but also the formation of hydrogen bonding during the gelation. The results of UV showed instability of IR780 solution and stability improvement of Res-IR780 solution under infrared radiation (IR) irradiation. Photothermal tests showed that Res-PTX@IR780 displayed better photothermal conversion and photothermal stability under multiple irradiations than PTX@IR780. The results of

Relationship between Evoked Auditory Steady-state Responses and Pure Tone Audiometry in Children with Different Levels of Hearing Loss / 听力学及言语疾病杂志

Objective To study the clinical significance of Chirp-ASSR and the characteristics of hearing loss patients by ASSR(auditory steady-state responses) under Chirp stimulation.Methods A total of 136 hearing loss children (5～10 years old) with 272 ears were distributed into four groups based on 500 Hz,1 000 Hz,2 000 Hz and 4 000 Hz auditory threshold arithmetic average:20～dB HL,40～dB HL,60～dB HL,and≥80 dB HL groups.To compare the correlation of the PTA and Chirp-ASSR in different frequencies domain through SPSS statistics 19.0 software,the data were used T-test and Pearson analysis.Results ①The group(≥80 dB HL) achieved a statistically significant higher reaction threshold than pure tone threshold.②The correlation index γ'of PTA and Chirp-ASSR showed a decline along with the hearing loss increase;It increased along with the test frequency,there was a significant difference between 500 Hz and 4 000 Hz(P＜0.05).Conclusion Chirp-ASSR is a frequency-specific electrophysiological test method,it could reflect the truthful listening ability,especially in mild,moderate,and severe hearing loss children.

Biocompatibility evaluation of lactide--trimethylene carbonate copolymers / 生物医学工程学杂志

Biocompatibility is the essential property of biomaterials, which is the essence of biomaterial evaluation as well as the foundation of the design and improvement of biomaterials. Several methods were carried out to evaluate the biocompatibility of poly(L-Lactide)-b-poly(trimethylene carbonate (PLLA-b-PTMC) and poly(D,L-Lactide)-b-poly(trimethylene carbonate) (PDLLA-b-PTMC) with poly(L-Lactide) (PLLA) and poly(trimethylene carbonate) (PTMC) as control, including extract liquid experiment, directly contact experiment of materials and cells, hemolytic ratio analysis and platelet adhesion investigation. The results revealed that all the materials exhibited an acceptable cytotoxicity, and proliferation of cells on the modified materials was less than that on the PLLA but more than that on PTMC. The results of hemocompatibility experiments showed that no significant hemolysis was detected when all the materials were in use; in addition, the numbers of platelets adhered on the surface of copolymers were smaller than that on the surface of PLLA, and the degree of platelet deformation was slighter. So, the biocompatibility of copolymers is similar to that of PLLA, the biocompatibility of PLLA is not remarkably changed by modification with PTMC, but rather is improved.

Self-assembly preparation of phosphorylcholine-containing poly (L-lactide) nanoparticles with solvent evaporation method and its characteristics / 中国组织工程研究

BACKGROUND: Phosphorylcholine-containing poly (L-lactide) (PLLA-PC) is a kind of novel amphiphilic copolymer with good biocompatibility and biodegradability. In the previous work, self-assembly micelles of PLLA-PC were prepared with film rehydration method. But it hardly formed micelle with film rehydretion method because the longer chains of LLA existed in the PLLA-PC copolymer. However, the mechanism of phosphotipid choline polymer with long hydrophobic chain forming micelle remains still unclear. OBJECTIVE: To prepare self-assembling nanoparticles of PLLA-PC using solvent evaporation method, and to explore the factors that affected the properties and stability of nanoparticles.METHOD: ① Nanoparticles were prepared with solvent evporation metod.PLLA-PC copolymer was dissolved into acetone, and the copolymer solution was added dropwise to distilled water with stirring to yield nanoparticles. The critical micelle concentration (CMC) was performed on the F-7000FL220-240V. The emission and excitation wavelength were 395 nm and 300 mm, respectively. Transmission electron microscopy (TEM) was carried out on a JEM-100CX electron microscope to observe the morphology of PLLA-PC nanoparticles. Dynamic light scattering measurements on nanoparticle solutions were performed on a NANOSIZE 3600 at room temperatire. ②Gel permeation chromatography(GPC)measurements were perfrmed on a Waters 717 apparatus equipped with an RI detector. THF was used as the mobile phase at a flow rate of 1.0 mlJmin. A 1 g/L solution (50 μL) was injected for each analysis. RESULTS AND CONCLUSION: TEM indicated that the PLLA-PC nanoparticles presented typical shell/core structure. The critical micelle concentration was determined by fluorescent probe method. The results showed that the CMCs were quite low ( 10~(-3) g/L) and were dependent on the LLA units in the copolymer. The size and size distribution of the nanoparticles were detected by dynamic light scattering. The results indicated that the size could be affected by the LLA units, concentration of the organic solution and the concentration of the aqueous solution of the nanoparticles. On the other hand, they hardly changed over the dilution with water, which was of great importance in venous injection. They degraded at 37℃. PLLA-PC nanoparticles with controllable sizes can be prepared with phase separation method and might serve as a novel material for drug delivery.

Theoretical research and application potential of amphiphilic polymers containing polyethylene glycol and their micelles used as drug carriers / 中国组织工程研究

OBJECTIVE: To review classification and synthesis of amphiphilic polymers containing polyethylene glycol and the application as drug carriers.DATA SOURCE: A computer-based research was conducted in SCI-Expanded, El Compendex and China Journal Full-text Database for articles concerning classification and synthesis of amphiphilic polymers containing polyethylene glycol and their micelles application as drug carriers published from January 2000 to July 2009.DATA SELECTION: A total of 616 articles were primarily obtained. Following reading titles and abstract, articles addressing detail classification and synthesis of amphiphilic polymers containing polyethylene glycol and representative micellar influencing factor were included. Totally 31 English and Chinese literatures were collected for further analysis.MAIN OUTCOME MEASURES: Classification, synthesis and drug vector mechanism of amphiphilic polymers containing polyethylene glycol and the micellar application as drug carriers were measured.RESULTS: Star-shaped copolymer could elevate micellar stability, but there were many arm numbers, whicti might induced a decrease in drug carrier volume. Special group introduced in copolymer contributed to the combination of drug and carrier. To connect target group could provide target transport property. The length and density of polyethylene glycol chain in copolymer was related to micellar function. Changed the length and density of polyethylene glycol could obtain polymer micelles that circulated in vivo for a long time.CONCLUSION: Amphiphilic polymers containing polyethylene glycol has outstanding potential in medical drug carrier field and isolation technique.

The hydrophilicity and cell affinity of polylactic acid containg bionic function group of phosphorylcholine / 生物医学工程学杂志

A series of novel biodegradable and bionic functional polymers, PLLA-PC-PLLA, were synthesized using L-lactide ring-opening polymerization by L-a-Glycerophosphorylcholine (PC) from nature source. The hydrophilicity of the polymers was investigated. The results made known that, as PC group was brought into the backbone of PLLA, PLLA-PC-PLLA gained much better hydrophilicity than did PLLA, and polar phosphatidylcholines probably transferred to the sample surface in aqueous environment. The relative growth ratios of ECV304 cells to the lixivium of all PLLA-PC-PLLA were higher than 84% in 5 d culture. The cells adhesion of ECV304 on the films of PLLA-PC-PLLA lagged as compared to that on PLLA, but they could proliferate and cover the films in total. The difference between PLLA-PC-PLLA and PLLA was due to the existence of PC group. Thus, PLLA-PC-PLLA, the same as PLLA, are not cytotoxic, and ECV304 can attach and proliferate on them. PLLA-PC-PLLA have potential applications in the fields of tissue engineering and drug delivery system.

Self-assembled monolayers as model systems to study the relation between biocompatibity and surface chemistry of biomaterials / 生物医学工程学杂志

The surface properties of biomaterials are essentially important to their biocompatibility. The complexity of surface composition and structure of biomaterials bring out the problem that it is difficult to make fully clear how the surface chemical properties and the structures of biomaterials control the biological reactions between the surfaces and proteins and/or cells. The structure of self-assembled monolayers (SAMs) is well established and SAMs have the characteristics of which a variety of functional groups and molecules can be introduced, either before or after the monolayer is formed, and diversified spectroscopy monitoring can be used to characterize SAMs and changes after their interactions with proteins or cells. Thus, SAMs are suitable model substrates for the study of the relationship between the surface chemical properties and biocompatibility of biomaterials. This paper reviews the researches on SAMs as models to study the absorption of proteins, cell adhesion and proliferation on materials, and the influences of both surface chemical functional groups and motion of molecular chains on hemocompatibility of biomaterials.

The study of photochemical immobilization of urease on polyether sulfone film surface / 生物医学工程学杂志

A new method of using photoactivable ester with azido group was described to immobilize urease on polyether sulfone(PES) film surface. The effects of photoactive enzyme concentration, temperature, pH, irradiation time on the activity of immobilized urease were investigated. Reused times and storage stability were also studied. The results showed that the surface concentration of urease immobilized on PES surface was about 0.33 mg/cm2. When the irradiation time was 5 minutes, the relative activity of immobilized urease was the highest and the activity increased with the increase of the concentration of photoactive urease solution. The optimum pH and temperature of immobilized urease were 7 and 50 degrees C respectively. The relative activity of immobilized urease was stable (50%) after 12 times reused at 50 degrees C.