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Laser Ablation - From Fundamentals to Applications || Matrix-Assisted Pulsed Laser Evaporation of Organic Thin Films: Applications in Biology and Chemical Sensors
摘要： Polymer and biomolecule processing for medical and electronics applications, i.e. the fabrication of sensors and biosensors, microarrays, or lab on chip devices is a cornerstone field which shows great promise. Laser based thin film deposition techniques such as pulsed laser deposition or matrix-assisted pulsed laser evaporation (MAPLE) are competing with conventional methods for integrating new materials with tailored properties for novel technological developments. Successful polymer and protein thin film deposition requires several key elements for depositing viable and functional thin films, i.e. the characteristics of the laser depositing system, the choice of targets and receiver substrates, etc. This chapter reviews the following topics: brief presentation of the MAPLE process including several examples of polymer materials deposited by MAPLE, thus illustrating the potential of the technique as a gentle laser-assisted deposition method. In particular, the “synthesis” of new materials, their analysis and correlation of the bulk and interface properties to its bio-environment shall be discussed as a method to tackle some bioengineering issues. We will also focus on recent breakthroughs of the MAPLE technique for the fabrication of functional devices, i.e. sensor devices based either on chemoresponsive polymers or on proteins.
关键词： saw,maple,hydroxyapatite nanoparticles,odorant-binding proteins,PEG-PCL-me,polyethylenimine,polyepichlorohydrin,ha,polyethylene glycol-co-polycaprolactone methyl ether,polyisobutylene,lactoferrin
更新于2025-09-19 17:13:59
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Investigations of Transient Plasma Generated by Laser Ablation of Hydroxyapatite during the Pulsed Laser Deposition Process
摘要： The optimization of the pulsed laser deposition process was attempted here for the generation of hydroxyapatite thin films. The deposition process was monitored with an ICCD (Intensified Coupled Charged Device) fast gated camera and a high-resolution spectrometer. The global dynamics of the laser produced plasma showed a self-structuring into three components with different composition and kinetics. The optical emission spectroscopy revealed the formation of a stoichiometric plasma and proved that the segregation in the kinetic energy of the plasma structure is also reflected by the individual energies of the ejected particles. Atomic Force Microscopy was also implemented to investigate the properties and the quality of the deposited film. The presence of micrometric clusters was seen at a high laser fluence deposition with in-situ ICCD imaging. We developed a fractal model based on Schr?dinger type functionalities. The model can cover the distribution of the excited states in the laser produced plasma. Moreover, we proved that SL(2R) invariance can facilitate plasma substructures synchronization through a self-modulation in amplitude.
关键词： hydroxyapatite thin film,pulsed laser deposition,plasma diagnostic,plasma structuring,SL(2R) invariance
更新于2025-09-16 10:30:52
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Calcium to phosphate ratio measurements in calcium phosphates using LIBS
摘要： In this study, we report the measurement of Ca/P ratio of hydroxyapatite using LIBS. Hydroxyapatite was prepared by wet chemical precipitation method with different stoichiometric ratios of Ca and P (1.5, 1.6, 1.67, 1.70, 1.80). Samples were then pelletized using KBr as a binder under a hydraulic press. Samples were irradiated with a laser beam and corresponding spectra were recorded. Spectra were further analyzed to calculate the Ca/P ratio which was then compared with the EDX for validation. LIBS results showed promise with a deviation of < 5% with the Stoichiometric ratios and EDX results.
关键词： EDX,Ca/P ratio,LIBS,hydroxyapatite,wet chemical precipitation
更新于2025-09-10 09:29:36
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Raman Spectroscopic Analysis to Detect Reduced Bone Quality after Sciatic Neurectomy in Mice
摘要： Bone mineral density (BMD) is a commonly used diagnostic indicator for bone fracture risk in osteoporosis. Along with low BMD, bone fragility accounts for reduced bone quality in addition to low BMD, but there is no diagnostic method to directly assess the bone quality. In this study, we investigated changes in bone quality using the Raman spectroscopic technique. Sciatic neurectomy (NX) was performed in male C57/BL6J mice (NX group) as a model of disuse osteoporosis, and sham surgery was used as an experimental control (Sham group). Eight months after surgery, we acquired Raman spectral data from the anterior cortical surface of the proximal tibia. We also performed a BMD measurement and micro-CT measurement to investigate the pathogenesis of osteoporosis. Quantitative analysis based on the Raman peak intensities showed that the carbonate/phosphate ratio and the mineral/matrix ratio were significantly higher in the NX group than in the Sham group. There was direct evidence of alterations in the mineral content associated with mechanical properties of bone. To fully understand the spectral changes, we performed principal component analysis of the spectral dataset, focusing on the matrix content. In conclusion, Raman spectroscopy provides reliable information on chemical changes in both mineral and matrix contents, and it also identifies possible mechanisms of disuse osteoporosis.
关键词： bone quality,sciatic neurectomy,hydroxyapatite,Raman spectroscopy,collagen crosslink,mineral maturity,osteoporosis,bone matrix
更新于2025-09-09 09:28:46
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A novel fluorescein-bisphosphonate based diagnostic tool for the detection of hydroxyapatite in both cell and tissue models
摘要： A rapid and efficient method for the detection of hydroxyapatite (HAP) has been developed which shows superiority to existing well-established methods. This fluorescein-bisphosphonate probe is highly selective for HAP over other calcium minerals and is capable of detecting lower levels of calcification in cellular models than either hydrochloric acid-based calcium leaching assays or the Alizarin S stain. The probe has been shown to be effective in both in vitro vascular calcification models and in vitro bone calcification models. Moreover we have demonstrated binding of this probe to vascular calcification in rat aorta and to areas of microcalcification, in human vascular tissue, beyond the resolution of computed tomography in human atherosclerotic plaques. Fluorescein-BP is therefore a highly sensitive and specific imaging probe for the detection of vascular calcification, with the potential to improve not only ex vivo assessments of HAP deposition but also the detection of vascular microcalcification in humans.
关键词： Alizarin S,fluorescein-bisphosphonate,hydroxyapatite,vascular calcification,calcium leaching assays
更新于2025-09-09 09:28:46
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Photofunctionalizing effects of hydroxyapatite combined with TiO <sub/>2</sub> on bone regeneration in rabbit calvarial defects
摘要： The hydrophilicity of bone graft material generally used as a carrier can play an important role in regulating bone morphogenetic protein (BMP) expression at the bone graft site. The hydrophilicity, altering physicochemical properties, and enhancing biological capabilities, can be increased via surface modi?cation through ultraviolet (UV) photofunctionalization and the effect on de novo osteogenesis could be further improved. Therefore, this study aimed to assess the effects of UV-irradiated TiO2-coated hydroxyapatite (HA) in combination with rhBMP-2 on bone regeneration in rabbit calvarial defects. The hydrophilicity of HA and TiO2-coated HA pellets was evaluated by measuring the contact angle of water droplets with UV irradiation. To compare de novo osteogenesis in rabbit calvarial defects, the rabbits were segregated into four different groups: negative control, HA, TiO2-coated HA, and TiO2-coated HA with UV; histomorphometric analysis and micro-computed tomography (μCT) imaging were performed after 4 and 8 weeks. In vivo analysis revealed that de novo osteogenesis occurred on the critical size defects in all groups and was signi?cantly increased in the TiO2-coated HA with UV group than in other groups (p < 0.05). The present results indicate that UV photofunctionalization promotes de novo osteogenesis.
关键词： hydroxyapatite,rabbit calvarial defects,ultraviolet,bone regeneration,titanium dioxide
更新于2025-09-04 15:30:14
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Preparation and characterization of a novel nanocomposite coating based on sol-gel titania/hydroxyapatite for solid-phase microextraction
摘要： In this work a novel nanocomposite coating with high thermal stability and high durability is prepared. The surface of the stainless steel as a support was initially modified by (3–mercaptopropyl)trimethoxysilane. Surface characteristics of pure titania (TiO2), pure hydroxyapatite (HAP) and Hap/TiO2 nanocomposite coating were investigated and compared by energy dispersive X–ray (EDX) spectroscopy as well as by field emission–scanning electron microscopy (FESEM). The mutual effects of components on each other were discussed. Addition of HAP sol to the pure TiO2 sol, considerably changes the coating morphology. The applicability of the sol–gel HAP/TiO2 fiber was assessed for the headspace solid–phase microextraction (HS–SPME) of benzene, toluene, ethylbenzene and xylenes (BTEXs) from water sample followed by gas chromatography–mass spectrometry (GC–MS). Important parameters affecting the extraction efficiency were investigated. The efficiency of HAP/TiO2 nanocomposite coating was compared with other reported fibers and showed very good results. Under optimal conditions, the detection limits (S/N = 3) were in the range of 0.04 to 1 μg L?1, and the limits of quantification (S/N = 10) were between 0.1 and 4 μg L?1. The relative standard deviations (RSDs) for each fiber (at 20 μg L?1 and n = 5) were in the range of 1.76 to 8.18%, while the RSDs between fibers were 3.03 to 10.02%. The method showed a large linearity in the range from 0.1 to 1000 μg L?1 with correlation coefficients of > 0.995.
关键词： Gas chromatography–mass spectrometry,BTEX,Hydroxyapatite,Solid-phase microextraction,Sol–gel technology,Titania
更新于2025-09-04 15:30:14