聚L-乳酸/二氧化硅纳米复合材料及其表面诱导生成类骨磷灰石的制备

为改善纳米SiO2粒子在聚L-乳酸基体中的分散性, 将乳酸齐聚物接枝到纳米SiO2粒子表面, 通过IR, 29Si MAS NMR和TGA对改性SiO2进行表征. 以聚L-乳酸(PLLA)为基体, 加入乳酸齐聚物接枝改性的二氧化硅(g-SiO2)粒子, 采用溶液浇铸法制备PLLA/g-SiO2纳米复合材料, 测试其在模拟体液(SBF)中的生物活性. 通过XRD, IR, SEM和EDS表征手段, 考察材料表面类骨磷灰石形成能力. 结果表明, 乳酸齐聚物成功地接枝到SiO2表面, 当反应36 h时, g-SiO2接枝率最大(9.22%). 随着g-SiO2含量增加和浸泡时间的延长, 材料表面最初形成的无定形沉积物矿化成碳酸羟基磷灰石(Carbonated hydroxyapatite, CHA), 钙磷比为1.72, 类似于人骨无机质, 表明g-SiO2的引入能明显加速复合材料表面CHA沉积, 该复合材料有望成为骨修复填充材料和组织工程支架材料.     

Promotion of cell affinity of porous PLLA scaffolds by immobilization of RGD peptides via plasma treatment

In the present work, RGDS (Arg-Gly-Asp-Ser) was immobilized on PLLA scaffolds with plasma treatment. The amount of immobilization, determined by HPLC, was confirmed to be in the effective order. Results from the culture of rat osteosarcoma (ROS), osteoblastic-like cells, demonstrate that the immobilization of RGDS could effectively enhance the attachment of ROS cells on PLLA and increase the cell density in PLLA scaffolds. In addition, experiments of in vitro mineralization indicate that there were more cells and mineralization focci in the RGDS-immobilized scaffolds, suggesting a tendency to form bone-like tissues, compared with the unmodified PLLA scaffold. On the other hand, the PLLA scaffolds immobilized with RGES (Arg-Gly-Glu-Ser) were much less effective in promotion of ROS attachment, suggesting that the enhancement on cell attachment was mainly due to the recognition of RGDS by the adhesion receptors on the cell membrane. The results presented in this work demonstrate that RGDS could be successfully immobilized on PLLA scaffolds with plasma treatment and such modification can make PLLA scaffolds more suitable for culture of osteoblast-like cells and for generation of bone-like tissues.     

Preparation of HMWCNT/PLLA nanocomposite scaffolds for application in nerve tissue engineering and evaluation of their physical,mechanical and cellular activity properties

This study was aimed to prepare biodegradable and porous nanocomposite scaffolds with microtubular orientation structure as a model for nerve tissue engineering by thermally induced phase separation (TIPS) method using dioxane as the solvent, crystalline poly (L‐lactic acid) (PLLA) and multi‐walled carbon nanotubes (MWCNTs). In order to overcome dispersion of MWCNTs in the PLLA matrix, heparinization of MWCNTs was performed. Solvent crystallization, oriented structure, the mean pore diameter and porosity percentage of the scaffolds were controlled by fundamental system parameters including temperature‐gradient of the system, polymer solution concentration and carbon nanotube content. Scanning Electron Microscopy (SEM), ImageJ, software and dynamic mechanical thermal analysis (DMTA) were used to investigate the structural and mechanical properties. TEM observation was carried out for characterization of nanotube dispersion in PLLA. It was found that the scaffolds containing heparinized multi‐walled carbon nanotubes (HMWCNTs) exhibited higher storage modulus, better carbon nanotube (CNT) dispersion and tubular orientation structure than those with non heparinized MWCNTs. In‐vitro studies were also conducted by using murine P₁₉ cell line as a suitable model system to analyze neuronal differentiation over a 2‐week period. Immunofluorescence and DAPI staining were used to confirm the cells' attachment and differentiation on the PLLA/HMWCNT nanocomposite scaffolds. Based on the results, we can conclude that the PLLA/HMWCNT scaffolds enhanced the nerve cell differentiation and proliferation, and therefore, acted as a positive cue to support neurite outgrowth. Copyright © 2015 John Wiley & Sons, Ltd.     

Biomimetic polymer/apatite composite scaffolds for mineralized tissue engineering

The material surface must be considered in the design of scaffolds for bone tissue engineering so that it supports bone cells adhesion, proliferation and differentiation. A biomimetic approach has been developed as a 3D surface modification technique to grow partially carbonated hydroxyapatite (the bonelike mineral) in prefabricated, porous, polymer scaffolds using a simulated body fluid in our lab. For the rational design of scaffolding materials and optimization of the biomimetic process, this work focused on various materials and processing parameters in relation to apatite formation on 3D polymer scaffolds. The apatite nucleation and growth in the internal pores of poly(L-lactide) and poly(D,L-lactide) scaffolds were significantly faster than in those of poly(lactide-co-glycolide) scaffolds in simulated body fluids. The apatite distribution was significantly more uniform in the poly(L-lactide) scaffolds than in the poly(lactide-co-glycolide) scaffolds. After incubation in a simulated body fluid for 30 d, the mass of poly(L-lactide) scaffolds increased approximately 40%, whereas the mass of the poly(lactide-co-glycolide) scaffolds increased by about 15% (see Figure). A higher ionic concentration and higher pH value of the simulated body fluid enhanced apatite formation. The effects of surface functional groups on apatite nucleation and growth were found to be more complex in 3D scaffolds than on 2D films. Surprisingly enough, it was found that carboxyl groups significantly reduced the apatite formation, especially on the internal pore surfaces of 3D scaffolds. These findings are critically important in the rational selection of materials and surface design of 3D scaffolds for mineralized tissue engineering and may contribute to the understanding of biomineralization as well.SEM micrograph of a poly(L-lactide) scaffold.     

A comparative study of the in vitro degradation of poly(l-lactic acid)/β-tricalcium phosphate scaffold in static and dynamic simulated body fluid

Porous poly(l-lactic acid)/β-tricalcium phosphate (PLLA/β-TCP) composite is a new promising scaffold for bone tissue engineering. Porous scaffolds fabricated by liquid anti-solvent precipitation principle were subjected to degradation in dynamic simulated body fluid (DSBF) and in static simulated body fluid (SSBF) at 37 °C for 24 weeks, respectively. Results indicated that a large number of apatite layer were formed on the scaffolds. The results further indicated that SBF flow decreased the degradation rate of molecular weight and compressive strength significantly. The porosity and mass changes were related to the apatite formation and SBF flow. All the results might be owed to the mutual effects of the flow of SBF and the addition of β-TCP. The degradation rate of scaffolds could be adjusted by the additional fraction of β-TCP to meet the requirements of application in vivo.     

草莓型SiO2/PMMA纳米复合微球的制备

在纳米二氧化硅水分散体系中,借助于碱性辅助单体1-乙烯基咪唑(1-VID)与未改性纳米二氧化硅表面羟基之间的酸-碱作用,通过1-VID与甲基丙烯酸甲酯(MMA)的自由基共聚合,制备了草莓型的SiO2/PMMA复合微球.整个反应过程中,纳米二氧化硅无需表面处理,体系中无需另外加入乳化剂或助乳化剂,微球表面吸附的纳米二氧化硅对颗粒起稳定作用.用动态光散射粒度分布仪测得复合微球粒径在120-330nm之间,热重分析结果表明,复合微球中二氧化硅含量介于15%-20%之间.透射电镜和扫描电镜显示所得复合微球具有草莓型结构,二氧化硅富集在表面.     

不同磺化及碱处理聚醚醚酮的表面化学组成及体外生物活性评价

提出一种酸碱结合改性聚醚醚酮（PEEK）方法,并评价其对PEEK表面类骨磷灰石形成的影响.结果表明,通过磺化处理引入-SO₃H,显著改善了样品的亲水性,且磺化程度与H₂SO₄浓度和磺化反应时间成正比,并影响样品的表面形貌.质量分数为85% H₂SO₄处理30 min的PEEK-S具有较好的改性效果.将PEEK-S进一步用NaOH处理,可继续引入Na元素并提高样品的亲水性,但会受处理时间的影响.模拟体液（SBF）浸泡的生物活性评价结果表明,磺化后碱处理24 h的PEEK-Na具有快速的类骨磷灰石沉积能力,浸泡3 d的样品表面即可完全被沉积的类骨磷灰石覆盖,表现出较佳的生物活性.此酸碱双重改性方法操作简单,可大幅度提升PEEK的生物活性,具有较好的应用前景.     

The synthesis and characteristic study of 6FDA-6FHP-NLO polyimide/SiO2 nanohybrid materials

Hybrid nanocomposite films of silica (SiO₂) in polyimide (PI) from 4,4^′-(hexafluoroisopropylidene) diphthalic arhydride (6FDA), 2,2-Bis (3-amino-4-hydroxyphenyl) hexafluoropropane (6FHP) and nonlinear optical (NLO) molecule have been successfully fabricated by an in situ sol-gel process. The silica content in the hybrid films was varied from 0 to 22.5 wt%. These nanocomposite films exhibit fair good optical transparency. Fourier transform infrared (FTIR) spectroscopy results confirm the formation of SiO₂ particles in PI matrix. Scanning electron microscope (SEM) images show that the SiO₂ phase is well dispersed in the polymer matrix. Their glass transition behavior and thermal stability were investigated by differential scanning calorimeter (DSC) and thermal gravimetric analysis (TG).     

聚乳酸蜂窝状多孔膜的形成与控制

以单一组分聚L-乳酸(PLLA)为成膜材料,利用水辅助法制备了聚乳酸(PLLA)蜂窝状多孔膜.利用扫描电镜(SEM)和原子力显微镜(AFM)观察多孔膜形貌.研究溶剂、溶液浓度、环境温度和湿度等因素对所成多孔膜结构的影响.实验结果表明,高湿度环境和具有一定浓度的聚合物溶液是制备蜂窝状多孔膜的必要条件.溶剂的挥发性是形成规整蜂窝状孔结构的关键因素.环境相对湿度由43%增加到91%,PLLA多孔膜的孔径由(1.75±0.24)μm增加到(11.50±1.43)μm,且孔呈现六边形的蜂窝状结构.扫描电镜断面和AFM表明:膜表面形成了深度约为1.8μm的单层孔结构.通过控制溶液浓度、环境温度和湿度等因素来控制膜的表面形貌及其所成蜂窝状孔的大小.最佳的成膜条件为溶剂CH2Cl2,湿度75%RH,温度34℃,浓度3 wt%.讨论了蜂窝状多孔膜的形成机理.     

Cell adhesive and growth behavior on electrospun nanofibrous scaffolds by designed multifunctional composites

Nanostructured biocomposite scaffolds of poly(l-lactide) (PLLA) blended with collagen (coll) or hydroxyapatite (HA), or both for tissue engineering application, were fabricated by electrospinning. The electrospun scaffolds were characterized for the morphology, chemical and tensile properties by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), water contact angle (WCA), Fourier transform infrared (FTIR) measurement, and tensile testing. Electrospun biocomposite scaffolds of PLLA and collagen or (and) HA in the diameter range of 200-700 nm mimic the nanoscale structure of the extracellular matrix (ECM) with a well-interconnection pore network structure. The presence of collagen in the scaffolds increased their hydrophility, and enhanced cell attachment and proliferation, while HA improved the tensile properties of the scaffolds. The biocompatibility of the electrospun scaffolds and the viability of contacting cells were evaluated by 4',6-diamidino-2-phenylindole dihydrochloride (DAPI) nuclear staining and by fluorescein diacetate (FDA) and propidium iodide (PI) double staining methods. The results support the conclusion that 293T cells grew well on composite scaffolds. Compared with pure PLLA scaffolds a greater density of viable cells was seen on the composites, especially the PLLA/HA/collagen scaffolds.     

A study on the bioactivity of chitosan/nano-hydroxyapatite composite scaffolds for bone tissue engineering

In order to increase the biocompatibility and bioactivity of chitosan, hydroxyapatite had been in situ combined into chitosan scaffolds. The bioactivity of the composite scaffolds was studied by examining the apatite formed on the scaffolds by incubating in simulated body fluid and the activity of preosteoblasts cultured on them. The apatite layer was assessed using scanning electronic microscope (SEM), X-ray diffraction (XRD), Fourier-Transformed Infrared spectroscopy (FTIR) and weight measurement. Composite analysis showed that after incubation in simulated body fluid on both of the scaffolds carbonate hydroxyapatite was formed. With increasing nano-hydroxyapatite content in the composite, the quantity of the apatite formed on the scaffolds increased. Compared with pure chitosan, the composite with nano-hydroxyapatite could form apatite more readily during the biomimetic process, which suggests that the composite possessed better mineralization activity. Furthermore, preosteoblast cells cultured on the apatite-coated scaffolds showed different behavior. On the apatite-coated composite scaffolds cells presented better proliferation than on apatite-coated chitosan scaffolds. In addition, alkaline phosphatase activities of cells cultured on the scaffolds in conditioned medium were assessed. The cells on composite scaffolds showed a higher alkaline phosphatase activity which suggested a higher differentiation level. The results indicated that the addition of nano-hydroxyapatite improved the bioactivity of chitosan/nano-hydroxyapatite composite scaffolds. On the other hand, that is to say composition of substrates could affect the apatite formation on them, and pre-loaded hydroxyapatite can enhance the apatite-coating. It will also be significant in preparation of apatite-coating polymer scaffolds for bone tissue engineering.     

聚酰亚胺/二氧化硅纳米尺度复合材料的研究

通过正硅酸乙酯（ＴＥＯＳ）在聚酰胺酸（ＰＡＡ）的Ｎ，Ｎ’ 二甲基乙酰胺（ＤＭＡｃ），溶液中进行溶胶 凝胶反应，制备出不同二氧化硅含量的聚酰亚胺／二氧化硅（ＰＩ／ＳｉＯ２）复合薄膜材料．二氧化硅含量低于１０ｗｔ％的样品是透明浅黄色薄膜；二氧化硅含量高于１０ｗｔ％的样品是不透明棕黄色薄膜．利用红外光谱、扫描电镜、热失重分析、动态力学分析、热膨胀系数测试和应力 应变测试等方法研究了此类材料的结构与性能．结果表明，ＰＩ／ＳｉＯ２纳米复合材料具有较聚酰亚胺更高的热稳定性和更高的模量；线膨胀系数显著降低；拉伸强度和断裂伸长随二氧化硅含量而变化，分别在１０ｗｔ％和３０ｗｔ％附近出现最大值     

Enhancing mechanical and thermal properties of PLLA ligaments with fumed silica nanoparticles and montmorillonite

Nanocomposites of poly(l-lactic acid) (PLLA) containing 2.5 wt% of fumed silica nanoparticles (SiO₂) and organically modified montmorillonite (OMMT) were prepared by solved evaporation method. From SEM micrographs it was observed that both nanoparticles were well dispersed into PLLA matrix. All nanocomposites exhibited higher mechanical properties compared to neat PLLA, except elongation at break, indicating that nanoparticles can act as efficient reinforcing agents. Nanoparticles affect, also, the thermal properties of PLLA and especially the crystallization rate, which in all nanocomposites is faster than that of neat PLLA. From the thermogravimetric curves it can be seen that neat PLLA nanocomposites present a relatively better thermostability than PLLA, and this was also verified from the calculation of activation energy (E). From the variation of E with increasing degree of conversion it was found that PLLA/nanocomposites decomposition takes place with a complex reaction mechanism, with the participation of two different mechanisms. The combination of models, nth order and nth order with autocatalysis (Fn–Cn), for PLLA and PLLA/OMMT as well as the combination of Fn–Fn for PLLA/SiO₂ give the better results. For the PLLA/OMMT the values of the E for both mechanisms are higher than neat PLLA. For the PLLA/SiO₂ nanocomposite the value of the E is higher than the corresponding value for PLLA, for the first area of mass loss, while the E of the second mechanism has a lower value.     

Facile method for fabrication of nanocomposite films with an ordered porous surface

This paper presents a novel and facile method for the fabrication of nanocomposite films with ordered porous surface structures. In this approach, a water-borne poly(styrene-co-butyl acrylate-co-acrylic acid)/silica nanocomposite dispersion was synthesized in situ by surfactant-free emulsion polymerization by using 3-allyloxy-2-hydroxy-1-propanesulfonate as a polymerizable surfactant. When this dispersion was dried to form a film at a certain temperature, an ordered porous structure could be directly obtained on the surface of the nanocomposite film. SEM, TEM, and AFM were employed to observe the morphology, and XPS and particle analyzer were used to analyze the surface composition of the ordered porous nanocomposite film and the particle size, respectively.     

Aerosol assisted chemical vapor deposition using nanoparticle precursors: a route to nanocomposite thin films

Gold nanoparticle and gold/semiconductor nanocomposite thin films have been deposited using aerosol assisted chemical vapor deposition (CVD). A preformed gold colloid in toluene was used as a precursor to deposit gold films onto silica glass. These nanoparticle films showed the characteristic plasmon absorption of Au nanoparticles at 537 nm, and scanning electron microscopic (SEM) imaging confirmed the presence of individual gold particles. Nanocomposite films were deposited from the colloid concurrently with conventional CVD precursors. A film of gold particles in a host tungsten oxide matrix resulted from co-deposition with [W(OPh)(6)], while gold particles in a host titania matrix resulted from co-deposition with [Ti(O(i)Pr)(4)]. The density of Au nanoparticles within the film could be varied by changing the Au colloid concentration in the original precursor solution. Titania/gold composite films were intensely colored and showed dichromism: blue in transmitted light and red in reflected light. They showed metal-like reflection spectra and plasmon absorption. X-ray photoelectron spectroscopy and energy-dispersive X-ray analysis confirmed the presence of metallic gold, and SEM imaging showed individual Au nanoparticles embedded in the films. X-ray diffraction detected crystalline gold in the composite films. This CVD technique can be readily extended to produce other nanocomposite films by varying the colloids and precursors used, and it offers a rapid, convenient route to nanoparticle and nanocomposite thin films.     

Effect of buffer in simulated body fluid on morphology and crystallinity of hydroxyapatite precipitated on 45S5 bioactive glass-derived glass–ceramic scaffolds: comparison of Good’s buffer systems and TRIS

In vitro tests that verify the ability of a material to form bone-like apatite precipitated (HAp) use a solution that imitates the inorganic part of blood plasma, simulated body fluid (SBF). During such tests, it is necessary to maintain a neutral pH, for which purpose the International Standards Organization recommends the TRIS (tris(hydroxymethyl)aminomethane) buffer (ISO 23,317:2014). To do this, TRIS buffer must remain inert, but, as we have previously reported, TRIS interacts with highly bioreactive materials (such as 45S5 Bioglass-derived scaffolds), thereby accelerating scaffold dissolution. In the search for an alternative to TRIS, we have also recently published results for the 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) and 3-(N-morpholino) propanesulfonic acid (MOPS) buffers, which were also unable to maintain a neutral pH in SBF. Thus, we here continue our search for a more suitable Good’s buffer by comparing BES (N,N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid) and TES (2-[(2-hydroxy-1,1-bis(hydroxymethyl) ethyl) amino] ethanesulfonic acid) with TRIS. 45S5-derived glass–ceramic scaffolds were tested under static–dynamic conditions for bone-like apatite formation using SBF + BES and SBF + TES solutions. The pH measurements, leachate analysis [atomic absorption spectrophotometry (AAS) (Ca²⁺, Si^IV), UltraViolet-Visible (UV-VIS) spectrophotometry (PO₄)^3?], and scaffold analysis [X-Ray powder diffraction analysis (XRD), X-ray fluorescent analysis (XRF), scanning electron microscopy (SEM)/energy dispersive spectroscopy (EDS), Brunauer.Emmett.Teller specific surface area analysis (BET)] all showed that both BES and TES quickly interacted with the tested material. Moreover, the kinetics of the glass–ceramic dissolution affected the crystallinity and morphology of the precipitated HAp. Based on our previous results and the present data, it appears that Good’s buffers are not suitable for the in vitro testing of bioactivity of highly bioreactive materials.     

Synthesis and Characterization of Biodegradable Poly(ϵ-caprolactone)-b-Poly(L-lactide) and Study on Their Electrospun Scaffolds

A series of multi-block copolymers, poly(L-lactide)-b-poly (?-caprolactone) (PLLA-b-PCL) were synthesized. The first step of the synthesis consisted of the transesterification between the PLLA and 1,4-Butanediol, followed by the copolymerization of PLLA-diols and PCL, using isophorone diisocyanate (IPDI) as a coupling agent. The synthesized polymers were characterized by Fourier transform infrared (FTIR) spectra, differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD). PLLA/PCL block copolymers were electrospun into ultrafine fibers. The morphology of the electrospun fibrous scaffolds were investigated by Scanning Electron Microscopy (SEM). Results showed that the morphology and diameter of the fibers were affected by the electrospinning solution concentrationan and different weight ratio of PLLA/PCL. These electrospun PLLA-b-PCL fibrous membranes exhibited good flexibility and deformability. In comparison with the electrospun PLLA membrane, the electrospun fibrous membranes of PLLA-b-PCL demonstrated an enhanced elongation with still high tensile strength and Young's modulus to be beneficial for tissue engineering scaffolds.     

Homogeneous organic/inorganic hybrid scaffolds with high osteoinductive activity for bone tissue engineering

Composite scaffolds of polymers/β-tricalcium phosphate (TCP) have been widely used for bone regeneration due to the combination of osteoinductivity of TCP and mechanical properties of the polymers. However, the difference in surface properties of the two material causes composite has poor uniformity and weak two-phase interaction, resulting in poor TCP release and weak new bone-forming ability. In this research, a TCP sol was developed to replace traditional TCP nanoparticles for the preparation of homogeneous polycaprolactone (PCL)/TCP sol nanofibrous scaffolds. It was found that compared with TCP nanoparticles, TCP sol homogeneously distributed in PCL nanofibers, and greatly improved the hydrophilicity, biodegradability, and mechanical properties of the scaffolds. It is also confirmed that loading TCP sol promoted the formation of bone-like apatite on the surface of the scaffolds. Biological experiments showed that all scaffolds supported rat bone marrow mesenchymal stem cells (rBMSCs) proliferation, especially scaffolds loaded with TCP sol. The increase in alkaline phosphatase activity and collagen production, enhanced calcium deposition, and up-regulation of osteocalcin expression demonstrated that the loading TCP sol expanded an advantage of scaffolds in promoting rBMSCs osteogenic differentiation, suggesting it dramatically improved the osteoinductive activity of PCL/TCP hybrid system and had a great potential application in bone regeneration.     

Preparation and characterization of polymer/silica nanocomposites via double in situ miniemulsion polymerization

Polymer/SiO₂ nanocomposite microspheres were prepared by double in situ miniemulsion polymerization in the presence of methyl methacrylate, butyl acrylate, γ‐methacryloxy(propyl) trimethoxysilane, and tetraethoxysilane (TEOS). By taking full advantage of phase separation between the growing polymer particles and TEOS, inorganic/polymer microspheres were fabricated successfully in a one‐step process with the formation of SiO₂ particles and the polymerization of organic monomers taking place simultaneously. The morphology of nanocomposite microspheres and the microstructure, mechanical properties, thermal properties, and optical properties of the nanocomposite films were characterized and discussed. The results showed that hybrid microspheres had a raspberry‐like structure with silica nanoparticles on the shells of polymer. The silica particles of about 20 nm were highly dispersed within the nanocomposite films without aggregations. The transmittance of nanocomposite film was comparable to that of the copolymer film at around 70–80% from 400 to 800 nm. The mechanical properties and the fire‐retardant behavior of the polymer matrix were improved by the incorporation of silica nanoparticles. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 3128–3134, 2010     

Nanocomposites of poly(l-lactide) and surface-grafted TiO2 nanoparticles: Synthesis and characterization

A new method of surface modification of TiO₂ nanoparticles by surface-grafting l-lactic acid oligomer was developed. The surface-grafting reaction was evaluated by Fourier transformation infrared (FTIR) and thermal gravimetric analysis (TGA). The results showed that l-lactic acid oligomer could be easily grafted onto the TiO₂ nanoparticles surface in the presence of stannous octanoate and the highest amount of grafted polymer was about 8.5% in weight. Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) results showed that grafted TiO₂ (g-TiO₂) in chloroform or PLLA matrix approximated to uniform, while unmodified TiO₂ nanoparticles tended to aggregate. The tensile strength of this material was greatly improved by the addition of g-TiO₂ nanoparticles in poly(l-lactide) (PLLA) matrix. The tensile strength of the g-TiO₂/PLLA nanocomposite containing 5 wt.% of g-TiO₂ was 72 MPa, which was 23.1% higher than that of pure PLLA. Even though the incorporation of the TiO₂ nanoparticles into PLLA led to the deterioration of its elongation at break, the g-TiO₂/PLLA nanocomposite also exhibited better ductility than that of TiO₂/PLLA nanocomposite.