银纳米链状材料的制备及近红外吸收性质

报道了利用水/油相界面反应,采用湿化学法合成银纳米链状材料的方法,并对这种材料的近红外吸收性质和光热转换性质进行了研究。TEM分析表明,银纳米材料为链状结构,直径约为50nm,长度分布范围较宽,从几十纳米至几百纳米。这种材料具有强的近红外吸收特性,随着还原剂加入量的增加,吸收带逐渐展宽(800～1300nm),而且平坦。这种材料具有优异光热转换性质,一经808nm激光照射,温度迅速提高。该材料优异的近红外吸收和光热转换性质,使其在红外断层成像和近红外热疗等领域具有广阔的应用前景。     

Photochemical synthesis of polygonal gold nanoparticles

In this paper, we propose a method to generate gold nanoparticles capable of absorbing near infrared light (NIR) radiation through a photochemical reaction. This approach does not require the use of either surfactants or polymers, reducing the difficulties that may arise in further chemical modifications for the gold nanoparticles. The gold nanoparticles with either triangular or hexagonal shapes were generated using the photo-reduction method, mixing hydrogen tetrachloroaurate with sodium oxalate, a reducing agent, in aqueous solution under illumination of a mercury lamp (λ_max = 306 nm) for more than 10 min. The size of the gold nanoparticles varies from 25 to 200 nm, which mainly depends on the duration of light illumination and the concentration of sodium oxalate. Furthermore, we demonstrate that the presence of the gold nanoparticles in aqueous solutions can effectively elevate the temperature of the solutions under irradiation of NIR light (808 nm) within a few minutes. The gold nanoparticles can be potentially used as suitable photothermal agents for hyperthermia.     

一个简便快速测定CO的纳米金表面等离子体共振吸收光谱法

CO主要由火焰或烤炉等碳的不完全燃烧所产生,是一种常温下为无色、无臭的有毒气体,人们受一氧化碳的污染在慢性中毒时完全意识不到它,有时甚至有舒适的感觉,这些特性更增加了它的危害性。因此,探索简便快速灵敏的CO检测方法具有重要意义。研究表明,在pH 7.2 磷酸盐缓冲溶液中,一氧化碳还原HAuCl₄ 生成近似球形的金纳米粒子(NG),其平均粒径为45 nm,在1.70, 2.20和9.70 keV处产生3个金元素的能谱峰,在540 nm处产生一个表面等离子体共振(SPR) 吸收峰。采用分光光度法优化了分析条件,选择磷酸盐缓冲缓冲溶液的pH为7.2,磷酸盐缓冲浓度为40 mmoL·L-1,HAuCl₄浓度为40.0 μg·mL-1,反应时间为5 min。在选定条件下,CO浓度在0.2～8.75 μg·mL-1范围内与其SPR吸收峰峰值成线性关系,检出限为0.1 μg·mL-1 CO。考察了共存物质对测定1.0 μg·mL-1 CO的影响。结果表明, 当相对误差在±5%之内,200倍的SO2-₃, PO3-₄, SO2-₄、CO2-₃, NO-₃;100倍的Zn2+, K+, BrO-₃, Na₂S, 乙醇, 甲醇;80倍的Ni2+,Cr3+,Co2+,Ca2+, Mg2+, Fe3+, 葡萄糖, Pb2+, Al3+, SeO2-₃, Na₂S₂O₃,甲醛;50倍的Mn2+不干扰测定。这表明该SPR光度法具有较好的选择性。采用本法测定了空气样品中CO含量,结果与气相色谱法一致,相对误差在1.8%～4.2%之间。     

Optical property of nanocomposite of mesoporous silica thin films incorporated with gold nanoparticles

Amino-functionalized mesoporous silica thin films (MTFs) are produced using surface active agent F127,and then gold nanoparticles are introduced into the pore channels to prepare the Au/SiO 2 nanocomposite.After assembling the gold,the amino-functionalized MTF undergoes some shrinkage but remains a periodic structure as demonstrated by X-ray diffraction (XRD) patterns.The nanocomposite shows an acute characteristic diffraction peak assigned to (111) plane of the face-centered-cubic structure of gold,indicating that gold nanoparticles crystallize well and grow in a preferred orientation in the pore channels.The surface plasma resonance (SPR) absorption peak near 570 nm undergoes a red-shift accompanied by a strengthening of intensity when HAuCl 4 is used to react with the amino groups on the internal pore surfaces for 4,6,and 8 h.The simulative results are consistent with the experimental ones shows that the absorption property of the Au/SiO 2 nanocomposite is influenced by the dipping time,which affects the size and volume fraction of embedded gold nanoparticles.     

Nanostars on a fiber facet with near field enhancement for surface-enhanced Raman scattering detection

A 4-pointed gold nanostar is proposed to form the array on a fiber facet to achieve a greatly enhanced near field intensity for Surface-Enhanced Raman Scattering (SERS) detection. The proposed gold nanostar array has a Surface Plasmon Resonance (SPR) peaked at a wavelength of ～650 nm with up to 45 times electric field intensity enhancement compared with the state-of-the-art nanorod design. It has a wideband SPR field enhancement spanned from 600 to 720 nm, which covers the wavelengths for both the excitation light (632.8 nm) and the Raman signal of the analytes (675–706 nm); With symmetrical structure it forms four hot spots in every unit cell and can detect best for light polarized horizontal or perpendicular to the waist of the nanostars. It also could be altered to tune the SPR and allows the fiber sensor to resonate at different wavelengths, as demonstrated by an example at 533 nm. All the above features make the gold nanostar-based compact and portable fiber sensor an attractive solution for SERS detection.     

Gold nanorod stabilized by thiolated chitosan as photothermal absorber for cancer cell treatment

Gold nanorod (GNR) has great potential in the field of cancer therapy because of its photophysical property in converting near-infrared (NIR) laser light into heat. Fabrication of GNRs by seed-mediated growth method with the aid of cetyltrimethylammonium bromide (CTAB) is a popular approach. However, due to high cytotoxicity of CTAB, it is necessary to modify the surface of CTAB-passivated GNRs for cell-related studies. In this study, thiolated chitosan was synthesized and harnessed to replace CTAB originally used to stabilize GNRs. The average size and morphological shape of CTAB-passivated GNRs (66.0 nm) and thiolated chitosan-modified GNRs (CGNRs) (84.9 nm) were determined by dynamic light scattering and transmission electron microscopy. X-ray photoelectron spectroscopy was used to confirm the existence of Au–S binding energy at 162.4 eV. Cytotoxicity study revealed that CGNRs were much biocompatible than CTAB-stabilized GNRs. Our results showed that CGNRs functionalized with folic acid (FA) could be internalized by human colon HT-29 cancer cells via folate-mediated endocytosis. From the viability of CGNR-laden HT-29 cells irradiated with 808-nm NIR laser light, we demonstrated that CGNR is a potential photothermal nano-absorber for the ablation of malignant cells under NIR laser exposure.     

Gold nanoflowers with mesoporous silica as “nanocarriers” for drug release and photothermal therapy in the treatment of oral cancer using near-infrared (NIR) laser light

In this experiment, we successfully developed nanocarriers in the form of gold nanoflowers coated with two layers of silica for the purposes of drug loading and NIR (near-infrared) photothermal therapy for the treatment of oral cancer. The gold nanoflowers converted NIR laser energy into heat energy. The cores were coated with a thin silica layer (AuNFs@SiO₂) to protect the gold nanoflowers from intraparticle ripening. The second layer was mesoporous silica (AuNFs@SiO₂@mSiO₂), which acted as a nanocarrier for anticancer drug (DOX) loads. The mean effective diameter of the nanoparticles was approximately 150–200 nm, whereas the peak absorption of the AuNFs was 684 nm. After the AuNFs were encapsulated by the silica shells, the plasmonic absorption peak of AuNFs@SiO₂ and AuNFs@SiO₂@mSiO₂ exhibited a red shift to 718 nm. When exposed to an 808 nm NIR laser, these crystals showed an obvious photothermal conversion in the NIR region and a highly efficient release of DOX. Biocompatibility was assessed in vitro using Cell Counting Kit-8 assays, and the results showed that the nanocarriers induced no obvious cytotoxicity. This nanomaterial could be considered a new type of material that shows promising potential for photothermal-chemotherapy against malignant tumours, including those of oral cancers.     

Encapsulation of Photosensitizers and Upconversion Nanocrystals in Lipid Micelles for Photodynamic Therapy

Photodynamic therapy (PDT) is a promising method for cancer therapy. However, it is constrained by limited penetration depth of visible light, hydrophobicity of photosensitizers, and lack of tumor targeting. In this work, the photosensitizer zinc phthalocyanine (ZnPc) and upconversion nanocrystals (UCNs) are encapsulated into OQPGA‐PEG/RGD/TAT lipid micelles. The UCNs acting as a nanotransducer convert deep‐penetrating near‐infrared (NIR) light to visible light for activating the photosensitizer. OQPGA‐PEG/RGD/TAT lipid micelles are used as a carrier for the photosensitizer, with improved biocompatibility and cancer‐targeting ability. The results show that the photosensitizer ZnPc‐ and UCNs‐loaded OQPGA‐PEG/RGD/TAT lipid micelles are nanoparticles with an average size of 25 nm. The lipid micelle nanoparticles are stable in water with low leakage of photosensitizer. The absorption peak of the photosensitizer overlaps with the emission peak of UCNs, so the visible fluorescence emitted from the UCNs upon excitation by the NIR laser at 980 nm can activate the photosensitizer to produce singlet oxygen for PDT. The targeting RGD peptide and cell‐penetrating TAT peptide on the surface help the nanoparticles getting into cancer cells. The OQPGA‐PEG/RGD/TAT lipid micelles encapsulated with both the photosensitizer ZnPc and UCNs could be used for targeted PDT by using deep‐penetrating NIR light as the light source.     

偏振控制光强调制型点阵SPR传感器研究

介绍了一种偏振控制光强调制型点阵表面等离子体共振(SPR)传感器,分析了入射角度、金膜厚度、起偏器设置、光源波长及数据处理方式对传感器灵敏度和线性范围的影响,并对632.8 nm与740 nm两种光源传感器系统进行了实验测试与分析.结果表明,偏振控制光强调制型点阵SPR传感器可将光经过表面等离子体共振所产生的偏振态变化...     

Fluorescent silver nanoparticles via exploding wire technique

Aqueous solution containing spherical silver nanoparticles of 20–80 nm size have been generated using a newly developed novel electro-exploding wire (EEW) technique where thin silver wires have been exploded in double distilled water. Structural properties of the resulted nanoparticles have been studied by means of X-ray diffractometer (XRD) and transmission electron microscopy (TEM). The absorption spectrum of the aqueous solution of silver nanoparticles showed the appearance of a broad surface plasmon resonance (SPR) peak centered at a wavelength of 390 nm. The theoretically generated SPR peak seems to be in good agreement with the experimental one. Strong green fluorescence emission was observed from the water-suspended silver nanoparticles excited with light of wavelengths 340, 360 and 390 nm. The fluorescence of silver nanoparticles could be due to the excitation of the surface plasmon coherent electronic motion with the small size effect and the surface effect considerations     

Enhanced surface plasmon resonance imaging detection of DNA hybridization on periodic gold nanoposts

We explore periodic gold nanoposts as substrates for the enhanced surface plasmon resonance imaging (SPRi) detection of DNA hybridization. Rigorous coupled-wave analysis was used to model and design the nanopost-based SPRi biosensor. Arrayed gold nanoposts on gold-coated glass substrate, with various widths and periodicity, were fabricated using electron-beam lithography and characterized with scanning electron and atomic force microscopy. A scanning-angle SPRi apparatus was used to conduct the kinetic analysis of DNA hybridization on nanopost-based sensor surface and assess the corresponding SPR signal amplification. Experimental results showed that both the nanostructure size and period influenced the SPR signal enhancement; the optimized 30 nm height, 50 nm size, and 110 nm period nanoposts provided a fivefold SPR signal amplification compared with the plain 50 nm thick gold film used as control.     

Extremophilic Polysaccharide for Biosynthesis and Passivation of Gold Nanoparticles and Photothermal Ablation of Cancer Cells

Extremophiles are the group of organisms that are far overlooked for exploring novel biomaterials in the field of material science and bionanotechnology. Extremophilic bacterial‐sulfated exopolysaccharide, mauran (MR), is employed for the bioreduction and passivation of gold nanoparticles (AuNps) to enhance the biocompatibility of AuNps and used for photothermal ablation of cancer cells. Here, various concentrations of MR solution are tested for the reduction of HAuCl₄ solution in the presence as well as in the absence of an external reducing agent, to produce mauran‐gold nanoparticles (MRAu Nps). These biocompatible nanocomposites are treated with cancer cell lines under in vitro conditions and NIR irradiated for complete ablation. MRAu Nps‐treated cancer cells on immediate exposure to infrared radiation from a femtosecond pulse laser of operating wavelength 800 nm are subjected to hyperthermia causing cell death. Biocompatible MR stabilization could fairly reduce the cytotoxicity caused by bare AuNps during biomedical applications. Application of a biocompatible polysaccharide from extremophilic bacterial origin for reduction and passivation of AuNps and used for a biomedical purpose is known to be first of its kind in bionanofusion studies.     

Synthesis,characterization, and toxicity of hollow gold nanoshells

Hollow gold nanoshells (HGN) with a diameter of 50–70 nm and tunable optical properties within the near-infrared region were synthesized from a substitution reaction using a sacrificial template, in which the morphological properties of the HGN were affected by the synthesis conditions. Using EDX line scan, the composition of the structure was determined to verify if the sacrificial template is completely consumed or residues remain after the chemical synthesis, obtaining that the final HGN structure contains about 11% of the remaining silver that showed no significant effect on the cell viability of a hNS1 cell line, but resulted as toxic on a C6 glioma cell line at high concentrations. The photothermal properties were evaluated using a NIR laser, which despite its low power showed the conversion of light into heat. This study was conducted to evaluate the potential of these nanostructures as therapeutic agents with an emphasis on toxicity.     

聚吡咯修饰的金纳米棒对肿瘤的光学相干层析成像的影响

聚吡咯(PPy)制备简单、生物相容性好,且在近红外(NIR)光谱范围内有很强的吸收,可作为一种良好的光热治疗试剂;同时,其NIR光吸收性质也可用于增强光学相干层析成像(OCT)的对比效果。因此,采用PPy对传统的OCT对比试剂——金纳米棒(GNR)进行表面修饰,有望获得对比效果更好且生物毒性较小的新型OCT对比试剂。选用吡咯为起始原料,在GNR表面进行一步简单的氧化聚合反应即可制备得到PPy修饰的金纳米棒(GNR-PPy)。利用紫外-可见吸收光谱,拉曼光谱和透射电子显微镜对制备的样品进行了分析和表征。构建小鼠荷瘤模型,以研究GNR-PPy对肿瘤OCT图像对比度的增强效果。采用中心波长为840 nm的OCT系统对注射了纳米粒子的肿瘤区域进行OCT成像。结果表明,肿瘤组织注射了GNR-PPy后,OCT信号衰减非常明显;与注射了GNR的OCT图像相比,840 nm光在GNR-PPy的OCT图像中的穿透深度明显更低。从OCT图像中抽提出一维的衰减曲线对OCT图像进行定量分析,发现注射有GNR-PPy肿瘤组织的OCT信号衰减系数明显高于注射了GNR的组织。表明,相对于GNR,GNR-PPy具有更好的OCT信号对比效果,这在增强肿瘤成像效果方面具有潜在应用价值。     

Preparation of hydrosol suspensions of elemental and core–shell nanoparticles by co-deposition with water vapour from the gas-phase in ultra-high vacuum conditions

In this study, efforts were placed in giving some in vitro key clues to the question on which is more efficient for the cancer hyperthermia between intracellular and extracellular modalities. Near infrared (NIR) photothermal responsive gold nanorods (GNRs) were adopted to cause cellular thermolysis either from inside or outside of cells. GNRs were synthesized with the size of 30.4?nm (in length)?×?8.4?nm (in width). Demonstrated by ICP-MS (inductively coupled plasmon mass spectroscopy), UV?CVis spectroscopy and transmission electron microscopy analyses, various cell uptake doses of nanoparticles were differentiated due to different molecular designs on GNRs surfaces and different types of cells chosen (three cancer cell lines and three normal ones). Under our continuous wavelengths (CW) NIR irradiation, it resulted that the cells which internalized GNRs died faster than the cells surrounded by GNRs. Furthermore, fluorescent images and flow cytometry data also showed that the NIR photothermal therapeutic effect was greater when the amount of internalized GNRs per cell was larger. Generally speaking, the GNRs assisted intracellular hyperthermia exhibited more precise and efficient control on the selective cancer ablation. To a larger degree, such a relationship between GNRs distribution and hyperthermia efficiency might be applied to wider spectra of cell types and heat-producing nanoparticles, which provided a promise for future cancer thermal therapeutic designs.     

倾斜光纤光栅溶液折射率传感器的实验研究

根据倾斜光纤光栅(TFBG)和表面镀金的TFBG传感器测量折射率的基本原理,通过OptiGrating软件模拟了不同浓度溶液下TFBG的透射谱和芯层模与某阶包层模耦合引起的谐振峰,初步得出了TFBG各阶包层模随着外界折射率的增大而向右偏移、在一定的传感范围内中心波长与外界折射率呈线性关系的结论。用小型离子溅射仪对TFBG镀45 nm厚度左右的金膜,并用扫描电镜在微观上观察镀膜效果。通过不同浓度下的NaCl溶液、MgCl₂溶液、CaCl₂溶液实验,对比研究了裸TFBG和镀金TFBG传感器对溶液折射率的传感特性。从而验证了模拟仿真得出的结论并定量分析得知：镀金后具有表面等离子体共振的TFBG溶液折射率灵敏度大于500 nm·RIU-1,而裸TFBG为2 nm·RIU-1左右,大约提高了200～300倍,且在一定范围内中心波长与溶液折射率的线性拟合度都在0.99以上。     

光照法在玻璃基底上原位生长金纳米结构及其光谱性质

 以硅烷化后吸附粒径小于10 nm的金种子的玻璃片为基底,聚乙烯吡咯烷酮为还原剂,在荧光灯照射条件下还原氯金酸,制备出表面具有金纳米粒子聚集结构的基底。用原子力显微镜、扫描电镜、X射线衍射、吸收和荧光光谱研究了基底的性质。结果表明：随着光照时间增加至20 h,金种子长大为平均粒径140 nm的不规则状多晶粒子,且出现双层粒子堆叠。基底的吸收光谱上出现了由金粒子的表面等离子体激元偶极子耦合引发的强烈吸收峰,随着粒子粒径增大,耦合峰在600~800 nm波段内连续红移升高,表明耦合程度不断增强。在223 nm紫外光的激发下,基底的荧光光谱上在405 nm处出现发射峰,是由金粒子表面激发电子和空穴的复合辐射造成的,发光强度随着基底上粒子平均尺度增加而减弱。     

光辐照精确调控金纳米星枝杈长度及其光热性能探究

金纳米星是一种具有尖状结构的多分枝纳米颗粒.为了使金纳米星枝杈长度可控,利用HEPES作为体系的还原剂、稳定剂及形状诱导剂,在制备过程中进行光辐照,得到的金纳米星枝杈长度比无光辐照时的金纳米星枝杈长度短,而且不同波长光辐照得到的金纳米星枝杈长度有显著不同.在此基础上,分析了金纳米星枝杈长度变化的物理过程,提出光诱导金纳米星生长过程中枝杈长度变化的理论模型.测量了不同枝杈长度的金纳米星在光辐照下一定时间内的温度变化,计算了金纳米星的光热转换效率.实验结果表明,光辐照制备金纳米星能够精确控制金纳米星枝杈长度范围,从而调控金纳米星的光热转换效率.     

Synergistic Effect of Photothermal Therapy and Chemotherapy Using Camptothecin‐Conjugated Gold Nanorods

A combinatorial treatment comprising thermal therapy and chemotherapy offers synergistic effects by inducing localized heat to targeted tumor sites and simultaneously delivering anticancer drugs to minimize systemic side effects and enhance the cytotoxic effect. In this study, a novel platform is developed for combining photothermal therapy and chemotherapy using drug‐conjugated gold nanorods (GNRs). Camptothecin (CPT), a model anticancer drug, is chemically conjugated onto GNRs through hydrolytic ester bonding. Upon near‐infrared (NIR) irradiation, localized heat from GNRs in target areas starts to destroy tissues and cells via photothermal therapy, and the elevated temperature accelerates hydrolysis of ester linkage, rapidly releasing drugs for chemotherapy. This combined NIR triggered thermal therapy and chemotherapy with CPT‐functionalized GNRs (CPT‐GNRs) presents a synergistic effect that has high efficacy in in vitro tests, thus providing a robust platform for efficient cancer treatments.     

SPR and SERS characteristics of gold nanoaggregates with different morphologies

In this study, surface plasmon resonance (SPR) and surface-enhanced Raman scattering (SERS) characteristics of gold nanoaggregates with different morphologies are examined to elucidate the correlation between SPR and SERS of the object. Nanoaggregates, defined as random aggregates (hereafter RA), elongated aggregates (hereafter EA) and two-dimensional layered aggregates (hereafter 2DLA) are fabricated by immobilizing colloidal gold nanoparticles on glass substrates. The color variation observed in the RA and EA samples indicates the variation in localized SPR excitations excited on the samples. The RA sample mostly shows a broadened and shifted SPR peak centered at 570 nm in addition to another peak in the longer wavelength region (∼700 nm), whereas in the EA sample a weak blue-shifted peak is observed near 450 nm in addition to a broadened peak centered at 570 nm covering a trail for another one near 700 nm. In the case of the 2DLA sample, more than one SPR peaks are observed in the longer wavelength region. The SERS observation confirms million times higher enhancement at least in Raman intensity using the gold nanoaggregates adsorbed by dye molecules. The EA sample of gold nanoparticles shows ∼5 times higher enhancement in Raman signal compared to that of the RA and 2DLA sample.