检测纳米微粒粒径方法的研究

用光子相关法、原子力显微镜和扫描电镜三种测试方法测定了同一标准样品的粒径，比较了三种测试方法在纳米粒径检测方面的特点。光子相关法给出纳米微粒的平均粒径和多分散系数，而原子力显微镜和扫描电镜在测定粒径的同时直接观察到微粒的外貌。     

Evaluation of the effects of biodegradable nanoparticles on a vaccine delivery system using AFM, SEM, and TEM

Hepatitis B is a deadly disease, and is carried by 30% of the world's population. Antibodies are produced through a series of three manual vaccinations during infancy and childhood. However, the current needle vaccination not only induces pain in patients, but also can be inconvenient to administer. This is particularly true for the case of newborn babies. Intranasal vaccination is emerging as an alternative parenteral drug delivery method that facilitates drug delivery without causing pain. Chitosan, which is obtained through the deacetylation of chitin from crustacea, is a cationic polymer that is biodegradable, avirulent, and highly absorptive. In this study, ionic gelation between chitosan and TPP was conducted to synthesize chitosan nanoparticles with sizes of 200-400nm and a surface potential of 55-60mV, and which can be used as Hepatitis B vaccine carriers. Then, Heptatitis B antigen protein was impregnated to manufacture chitosan-recombinant gene vaccine protein (RGVP) nanoparticles. AFM, SEM, TEM, and STEM were used to analyze the manufactured nanoparticles, whose function as drug carriers and whose usefulness for intranasal vaccination were confirmed through in vivo tests with SD rats.     

Characterization of human ovarian teratoma hair by using AFM, FT-IR, and Raman spectroscopy

The structural, physical, and chemical properties of hair taken from an ovarian teratoma (teratoma hair) was first examined by atomic force microscopy (AFM), Fourier transform infrared (FT-IR), and Raman spectroscopy. The similarities and differences between the teratoma hair and scalp hair were also investigated. Teratoma hair showed a similar morphology and chemical composition to scalp hair. Teratoma hair was covered with a cuticle in the same manner as scalp hair and showed the same amide bonding modes as scalp hair according to FT-IR and Raman spectroscopy. On the other hand, teratoma hair showed different physical properties and cysteic acid bands from scalp hair: the surface was rougher and the adhesive force was lower than the scalp hair. The cystine oxides modes did not change with the position unlike scalp hair. These differences can be understood by environmental effects not by the intrinsic properties of the teratoma hair.     

Differentiation of human hair by colour and diameter using light microscopy,digital imaging and statistical analysis

This research introduces and evaluates a novel method that offers the potential of providing objective criteria to forensic microscopical hair comparisons. The method combines hair diameter with numeric characterisations of red, green, and blue colour content as determined with the use of digital imaging at defined locations of the hair. Thirty hairs were collected from each of twenty participants, all with naturally coloured brown hair. The hairs were examined with an Olympus BX53® polarising light microscope and digital images were viewed with an Olympus DP72® camera under 400× magnification. Using Olympus cellSens^? Entry software, hair diameter was measured at 1000, 1500 and 2000 m from the base of the root. The Olympus cellSens^? Entry software uses a red, green and blue (RGB) colour model to quantitatively define the colour of each pixel on an image based on its composition of these three principal colour components. This software was used to collect numerical characterisations of hair colour at each distance interval. The diameter and colour values for each hair were compared using discriminant analysis (DA) and principal component analysis. Although a large amount of intrapersonal variation was observed, the degree of interpersonal variation was greater and enabled the statistical model to differentiate between the hair samples from each participant. The DA model achieved sample reclassification with an error rate of 7.33%. A validation study was conducted on a subset of hair samples from which 18 of the 20 were correctly assigned to the participant from whom they originated. These results support the potential of this method to provide an objective addition to current microscopical hair comparison practices.     

Synchrotron nanoscopy imaging study of scalp hair in breast cancer patients and healthy individuals: Difference in medulla loss and cortical membrane enhancements

Nanoscopic synchrotron X‐ray imaging was performed on scalp hair samples of patients with breast cancer and healthy individuals to investigate any structural differences as diagnostic tool. Hair strands were divided into 2‐3 segments along the strands from root to tip, followed by imaging either in projection or in CT scanning with a monochromatic 6.78‐keV X‐ray using zone‐plate optics with a resolving power of 60 nm. All the examined cancer hairs exhibited medulla loss with cancer stage‐dependent pattern; complete loss, discontinuous or trace along the strands. In contrast, medullas were well retained without complete loss in the healthy hair. In the CT‐scanned axial images, the cortical spindle compartments had no contrast in the healthy hair, but appeared hypointense in contrast to the surrounding hyperintense cortical membrane complex in the cancer hair. In conclusion, observation of medulla loss and cortical membrane enhancements in the hair strands of breast cancer patients demonstrated structural variations in the cancer hair, providing a new platform for further synchrotron X‐ray imaging study of screening breast cancer patients. Microsc. Res. Tech. 79:23–30, 2016. © 2015 Wiley Periodicals, Inc.     

Atomic force microscopy as a tool for study of human hair

Atomic force microscopy (AFM) is a newly developed microscopic technique that offers high-resolution power, less intrusive measurement, and requires little sample pretreatment for elucidating structures of biological materials in three dimensions and in their natural environment. In this study, AFM has been used not only as an imaging technique for examining human hair structure at high resolution, but also as a tool for quantitative assessment of the effect of treatment in 10 mM phosphate buffered saline of pHs 3.0, 7.0, and 11.0 and heating on human hair structure. It is observed that the hair cuticle is a sensitive indicator of external influences on hair structure, and that its height can be used as a parameter for quantitative assessment. The experimental results obtained show that the swelling of hair caused by the incubation in the buffer decreases with the increase of the pH values and that, depending on the duration of heating, the hair undergoes structural expansion and shrinkage. This study demonstrates that AFM can be used as a valuable alternative to conventional microscopic techniques for hair research.     

Multiphoton fluorescence lifetime imaging of human hair

In vivo and in vitro multiphoton imaging was used to perform high resolution optical sectioning of human hair by nonlinear excitation of endogenous as well as exogenous fluorophores. Multiphoton fluorescence lifetime imaging (FLIM) based on time-resolved single photon counting and near-infrared femtosecond laser pulse excitation was employed to analyze the various fluorescent hair components. Time-resolved multiphoton imaging of intratissue pigments has the potential (i) to identify endogenous keratin and melanin, (ii) to obtain information on intrahair dye accumulation, (iii) to study bleaching effects, and (iv) to monitor the intratissue diffusion of pharmaceutical and cosmetical components along hair shafts.     

Elemental and molecular imaging of human hair using secondary ion mass spectrometry.

Secondary ion mass spectrometry (SIMS) is used to image the spatial distribution of elemental and molecular species on the surface and in cross sections of doped human hair using a magnetic sector SIMS instrument operated as an ion microprobe. Analysis of electrically insulating, non-planar hair samples requires one of two different methods of charge compensation to be used depending on the polarity of the sputtered secondary ions. For detection of positive secondary ions, the hair is imaged using a approximately 0.5 micron diameter, 19.5 keV impact energy, O- microbeam with no auxiliary electron bombardment. For detection of negative secondary ions, a approximately 0.2 micron diameter, 14.5 keV impact energy Cs+ microbeam is used in conjunction with normal incidence, low-energy electron bombardment. Both of these methods allow submicrometer spatial resolution elemental and molecular secondary ion images to be obtained from hair samples without metallic coating of the sample surface prior to analysis. Several examples are presented that reflect potential application areas for these analytical methods.     

Preparation of cell membranes for high resolution imaging by AFM

Studies of cell membrane structure by atomic force microscopy (AFM) have been limited because of the softness of cell membranes. Here, we utilize a new technique of sample preparation to lay red blood cell membranes on the top of a mica surface to obtain high resolution images by in-situ AFM on both sides of cell membranes. Our results indicate that the location of oligosaccharides and proteins in red blood cell membranes might be different from the current membrane model. The inner membrane leaflet is covered by dense proteins with fewer free lipids than expected. In contrast, the outer membrane leaflet is quite smooth; oligosaccharides and peptides supposed to protrude out of the outer membrane leaflet surface might be actually hidden in the middle of hydrophilic lipid heads; transmembrane proteins might form domains in the membranes revealed by PNGase F and trypsin digestion. Our result could be significant to interpret some functions about red blood cell membranes and guide to heal the blood diseases related to cell membranes.     

SEM investigation of interfacial dislocations in nickel-base superalloys

Chromatography is a widely used separation unit operation for separating nanomaterials such as proteins and enzymes, quantum dots and carbon nanotubes. An understanding of the chromatographic stationary phase on a nanoscale would be extremely helpful in improving the process and developing efficient and new materials. This study is an attempt to characterize the stationary phase in its swollen wet state using environmental scanning electron microscope (ESEM) and atomic force microscopy (AFM). Observation of the wet beads using ESEM is limited to a micron-range resolution. However, AFM can be used in wet mode to characterize the stationary phase in both wet and dry states with nanometric resolution. In the swollen state, microscale cracks were observed on the surface and this may explain the high mass transfer rate and lower back pressures of the stationary phase. The structures on the surface of the stationary phase depict that the micron-sized beads may be composed of nanometric beads.     

AFM针尖-试样面作用力连续介质方法研究

介绍了目前研究纳米接触问题的方法；根据Hamaker理论，利用连续介质方法，建立了原子力显微镜针尖和试样面接触的包括斥力项的力学模型；对模型进行了仿真，仿真结果同实验现象一致。将纳米接触问题的研究领域从非接触区域扩展到间歇接触区域。为原子力显微镜的进一步研究。实现原子操纵提供理论基础。     

Optimized hand fabricated AFM probes for simultaneous topographical and electrochemical tapping mode imaging

In this work hybrid AFM-electrochemical (SECM) probes to be used in dynamic atomic force microscopy are presented. These nanosensors are hand fabricated from gold microwires using a simple benchtop method. They display proportions close to commercially available silicon and silicon nitride cantilevers giving comparable performance in terms of resolution and imaging stability. The remarkable characteristic of these hybrid nanosensors is that they allow the coupling of 3D imaging ability and versatility of atomic force microscopy with the power of electrochemical methods. Local measurement of electrochemical-activity of a test sample consisting of gold bands functionalized by redox-labeled nanometer-sized polyethylene glycol chains has been achieved with simultaneous imaging of the 3D surface topography at high resolution. These hybrid AFM-SECM tips are capable of sensing local electrochemical currents down to ∼10 fA emphasizing the sensitivity and resolution of this technique.     

基于数学形态学方法的AFM探针建模研究

AFM扫描图像可被认为是探针针尖的形貌和扫描样品表面形貌的数学形态学卷积结果,需要用反卷积的方法排除扫描图像中探针形貌引起的失真影响。本文在已有基于数学形态学的探针盲建模算法基础上,提出了一种可快速实现特征点优化提取的方法,同时提出了一种可降低最优降噪阈值估计复杂性的基于临界阈值搜索新方法。最后给出了仿真与CNT扫描图像的重构实验结果。实验表明,本文介绍的方法提高了探针建模的计算速度和建模精度,可以对AFM成像质量进行有效的失真修正和改善。     

基于AFM的光盘形貌研究

介绍了原子力显微镜(AFM)的原理及特点。用AFM对光盘上记录信息用的凹坑结构进行了三维检测,并对测量结果进行了分析。结论表明AFM在光盘质量检测过程中具有独特的优势。