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

Chronic injection of corticosterone induces depression and impairment of learning and memory in mice / 中国比较医学杂志

Objective To Study the depression-like behavior and impairment of learning and memory induced by chronic injection of corticosterone in mice. Methods Forty male C57BL/6J mice were divided into four groups, the control group, and the corticosterone groups(20,40,80 mg/kg). The mice received subcutaneous injection of corticosterone once a day for 21 days. The depression-like behaviors were detected by open field test(OFT), tail suspension test(TST)and forced swimming test(FST). To select the most effective dose of corticosterone, TST, FST, object location recognition test, and Morris water maze(MWM)test were used to study the corticosterone-induced depression-like behaviors and impairment of learning and memory in the mice. Results Compared with the control group, the movement distance and duration were significantly decreased in the corticosterone injection groups(40,80 mg/kg)(P< 0.01 or P< 0.05). In the TST group,the immobilization time was significantly increased in the corticosterone injection group(40,80 mg/kg)(P< 0.05). The TST and FST showed that the immobilization time of the corticosterone injection group(40 mg/kg)was significantly increased(P < 0.05). The object recognition test showed that the discrimination indexes of the object location recognition were decreased in the corticosterone injection group(40 mg/kg). The MWM test showed that the escape latency was increased(P< 0.05),and the number of crossing in target quadrant and the velocity in target quadrant were decreased(P< 0.05)in the corticosterone injection group(40 mg/kg). Conclusions Chronic injection of corticosterone can induce depression accompanied with learning and memory impairment in mice.

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.

Effect of processing parameters on the degradation of calcium polyphosphate bioceramic for bone tissue scaffolds / 生物医学工程学杂志

This study was undertaken to elucidate the degradation regularity of calcium polyphosphate (CPP) scaffolds with different preparation parameters. CPP scaffolds with different main crystalline phases were prepared by controlling the particle size of the calcining stuff and the calcining heat. Specimens were soaked into Tris-buffer solution and simulated body fluid (SBF) for 60 days. Results show: alpha-CPP degrades faster than does beta-CPP, and beta-CPP degrades faster than does gamma-CPP; the lower the sinter temperature, the better the degradation of CPP morever, the degradation rate of CPP is inversely proportional to the original particle size. These data suggest that crystal type, sinter temperature and particle size influence the degradation rate of CPP markedly.

Structure and performance of calcium polyphosphate for bone tissue engineering / 生物医学工程学杂志

Porous calcium polyphosphate (CPP) has shown promise of tissue engineered implant application because of the biocompatibility and biodegradation. CPP with different polymerization degree were prepared by controlling the calcining time, and its polymerization degree could be calculated by developed method in this paper. Different crystal types CPP were prepared by quenching from the melt and crystallization of amorphous CPP. From the in vitro degradation, carried out in Tris-HCl buffer, the degradation velocity of CPP was controllable. The weight loss of CPP with different polymerization degrees and crystal types were different. With the increasing of polymerization degree, the weight loss during the degradation was decreasing, contrarily the strength of CPP was increasing. The amorphous CPP could degrade completely in 17 days while gamma-CPP do completely in 25 days. The degradation velocity beta-CPP and alpha-CPP was slower than gamma-CPP and the weight loss was about 12% and 5% respectively. The results of this study indicate that CPP have potential applications for bone tissue engineering as inorganic polymeric biomaterials.

Progress in study of self-assembling peptides / 生物医学工程学杂志

Self-assembly of peptides is ubiquitous in the body of creatures. The molecules of peptides combine with each other to form proteins with different functions through self-assembly. The formation of a specific conformation of one type of protein is owing to the self-assembly of its compositive amino acids. So, researchers can design self-assembly of peptides at the molecular level and can control its formation and configuration. It has the potential for application in the preparation of new medicines and biomaterials. In recent years, self-assembling peptides have been increasingly high-lighted and used to simulate the function of natural biomolecules, to synthesize peptide-medicine, and to serve as the carriers of medicine.

The advance in researches for biomedical intelligent polymer materials / 生物医学工程学杂志

The properties of biomedical intelligent polymer materials can be changed obviously when there is a little physical or chemical change in external condition. They are in the forms of solids, solutions and polymers on the surface of carrier, including aqueous solution of hydrophilic polymers, cross-linking hydrophilic polymers (i.e. hydrogels) and the polymers on the surface of carrier. In this paper are reviewed the progress in researches and the application of biomedical intelligent polymer materials.