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Mini-review: Laser-induced formation of microbubbles - biomedical implications
摘要： Recent work is summarized that shows how microbubbles may have potential utility in biomedical situations as (i) highly localized generators of intense whitelight in an aqueous environment, (ii) disruptors of matter in aqueous solution, (iii) essential precursors in laser-writing structures on substrates on which biological cells can be spatially aligned, and (iv) mediators in fabrication of hierarchical nano-structures that enhance signals in biological Raman spectroscopy. Indeed, microbubbles generated upon laser irradiation of surfaces have many more ramifications than originally thought, with implications in laser modification of surfaces producing either hydrophilicity or hydrophobicity. Many more possibilities remain to be explored and exploited.
关键词： Raman spectroscopy,biomedical applications,laser-induced formation,microbubbles,surface modification
更新于2025-09-10 09:29:36
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Reusable fiber taper sensor based on the metastability of gold nanoparticles
摘要： This work presents the design and implementation of a reusable-tapered optical fiber sensor (RFS). We used the RFS together with a white light source to analyze the metastability of gold nanoparticles. With the RFS we observed that reaction limited aggregation occurred when modifying the concentration of metastable gold nanoparticles (MAuNPs). This was detected by a red-shift and a broadening of the absorption band. The transition from a metastable to a stable state, regardless of the concentration of the MAuNPs, was achieved by the addition of glucose. The changes in the refractive index of the solution due to the presence of glucose and the stability of the MAuNPs were successfully detected by the RFS. Diffusion limited aggregation of the MAuNPs was rapidly triggered after the addition of insulin. Finally, to gain a better understanding of our results we used Raman spectroscopy together with a hollow core photonic crystal optical fiber (HC-PCF) and studied the chemical interactions between the MAuNPs and glucose and between the MAuNPs and insulin.
关键词： glucose,Raman spectroscopy,metastable gold nanoparticles,reusable-tapered optical fiber sensor,insulin
更新于2025-09-10 09:29:36
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Raman spectroscopic characterisation of photo-active keratin doped with Methylene Blue for wound dressings and tissue engineering
摘要： BACKGROUND: The design of wound dressings with extraordinary functionalities that fully address the problem of wound healing is an ambitious challenge in biomedical ?eld. Keratin is a protein most abundant in nature, being the major component of wool, feather, hair, etc., with promising applications in biomedical and regenerative medicine ?elds. A high level of antibacterial functionality is another desirable property for applications in biomedical ?eld in response to the increasing resistance of bacteria to antibiotics. One of the emerging methods of disinfection and sterilization is the antimicrobial photodynamic therapy (APDT), which uses light combined to a photosensitizer and oxygen to produce phototoxic species. OBJECTIVE: Biomatrices (photo-active keratin) made of wool keratin functionalized with methylene blue, a powerful photo-sensitizer, have been developed and tested as systems that combine the bioactive properties with the antimicrobial photodynamic functionality. METHODS: The biomatrix resistance to photo-degradation and the formation of reactive oxygen species were evaluated by spectroscopic methods, whereas the antibacterial properties were tested towards gram-positive bacteria. RESULTS: The Raman analysis revealed that speci?c damages occur at sensitive amino acid sites, selectively, rather than indiscriminately. However, keratin resulted to be a suitable biomaterial for APDT, since it has enough resistance to photo-degradation and the radical-induced oxidation is not able to induce strong structural changes in the protein. CONCLUSIONS: The results clearly indicate the potential use of these novel photo-active keratin biomatrices in wound dressing and tissue engineering.
关键词： reactive oxygen species,Raman spectroscopy,antimicrobial photodynamic activity,Keratin
更新于2025-09-10 09:29:36
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[Studies in Computational Intelligence] Advances in Neural Computation, Machine Learning, and Cognitive Research II Volume 799 (Selected Papers from the XX International Conference on Neuroinformatics, October 8-12, 2018, Moscow, Russia) || Artificial Neural Networks for Diagnostics of Water-Ethanol Solutions by Raman Spectra
摘要： The present paper is devoted to an elaboration of a method of diagnosis of alcoholic beverages using artificial neural networks: the inverse problem of spectroscopy – determination of concentrations of ethanol, methanol, fusel oil, ethyl acetate in water-ethanol solutions – was solved using Raman spectra. We obtained the following accuracies of concentration determination: 0.25% vol. for ethanol, 0.19% vol. for fusel oil, 0.35% vol. for methanol, and 0.29% vol. for ethyl acetate. The obtained results demonstrate the prospects of using Raman spectroscopy in combination with modern data processing methods (artificial neural networks) for the elaboration of an express non-contact method of detection of harmful and dangerous impurities in alcoholic beverages, as well as for the detection of counterfeit and low-quality beverages.
关键词： Neural networks,Raman spectroscopy,Inverse problems,Water-ethanol solutions
更新于2025-09-10 09:29:36
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Ab initio Calculations of Phonon Dispersion in CdGa2S4
摘要： The phonon spectrum of CdGa2S4 has been experimentally investigated by Raman spectroscopy and theoretically analyzed using the density functional theory (DFT). Eleven active Raman modes (at 83, 135, 165, 219, 243, 260, 310, 322, 352, 361, and 392 cm–1) have been detected and identified. The identification of all vibrational modes is based on consideration of the point symmetry group. The results are compared with the existing experimental IR spectroscopy and Raman scattering data.
关键词： Raman spectroscopy,phonon dispersion,CdGa2S4,lattice dynamics,density functional theory
更新于2025-09-10 09:29:36
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Driving chemical interactions at graphene-germanium van der Waals interfaces via thermal annealing
摘要： Despite its extraordinary charge carrier mobility, the lack of an electronic bandgap in graphene limits its utilization in electronic devices. To overcome this issue, researchers have attempted to chemically modify the pristine graphene lattice in order to engineer its electronic bandstructure. While significant progress has been achieved, aggressive chemistries are often employed which are difficult to pattern and control. In an effort to overcome this issue, here we utilize the well-defined van der Waals interface between crystalline Ge(110) and epitaxial graphene to template covalent chemistry. In particular, by annealing atomically pristine graphene-germanium interfaces synthesized by chemical vapor deposition under ultra-high vacuum conditions, chemical bonding is driven between the germanium surface and the graphene lattice. The resulting bonds act as charge scattering centers that are identified by scanning tunneling microscopy. The generation of atomic-scale defects is independently confirmed by Raman spectroscopy, revealing significant densities within the graphene lattice. The resulting chemically modified graphene has the potential to impact next-generation nanoelectronic applications.
关键词： graphene,van der Waals interfaces,germanium,Raman spectroscopy,chemical bonding,scanning tunneling microscopy,thermal annealing
更新于2025-09-10 09:29:36
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A Low-Cost Stable SERS Substrate Based on Modified Silicon Nanowires
摘要： In this paper, we report fabrication of a simple, stable, low-cost, and easy-to-fabricate substrate for surface enhanced Raman spectroscopy (SERS) applications. Silicon nanowires are one of the widely used nanostructures in different fields of nanotechnology. Through creating and varying the gap between nanowires and reducing their filling ratio and tapering, silicon nanowires are converted to applicable SERS substrates. Furthermore, the effects of annealing and post-KOH etching on these silver-coated silicon nanowire substrates are examined. It is shown that the applied processes remarkably enhance the captured Raman signal. For samples etched with KOH method, an optimized etching time at which the Raman signal reaches its maximum value is obtained as well. Finally, an ultra-high enhancement in the Raman signal is obtained.
关键词： Silicon nanowire,Surface-enhanced Raman spectroscopy,SERS substrates
更新于2025-09-10 09:29:36
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Machine learning algorithms applied to Raman spectra for the identification of variscite originating from the mining complex of Gavà
摘要： Variscite is an aluminium phosphate mineral widely used as a gemstone in antiquity. Knowledge of the ancient trade in variscite has important implications on the historical appreciation of the commercial and migratory movements of human population. The mining complex of Gavà, which dates from the Neolithic, is one of the oldest underground mine sites in Europe, from where variscite was extracted from several mines and at different depths, providing minerals with different properties and a range of colours. In this work, machine learning algorithms have been used to classify variscite samples from Gavà with regard to the identification of their mine of origin and extraction depth. The final objective of the study was to see if the Raman spectroscopic signatures selected by these algorithms had a key spectral significance related to mineral structure and/or composition and validate the use of these computational procedures as a useful tool for detecting variances in the mineral Raman spectra that could facilitate the assignment of the specimens to each mine.
关键词： high‐dimensional data,mineral classification,Raman spectroscopy,archaeometry,Neolithic mines of Gavà
更新于2025-09-10 09:29:36
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Plasmon-tunable Au@Ag core-shell spiky nanoparticles for surface-enhanced Raman scattering
摘要： A facile synthetic approach has been developed to prepare uniform and size-tunable spiky Au@Ag core-shell nanoparticles (NPs) to tailor the localized surface plasmon resonance (LSPR) properties. The gradual assembly of small Au nanocrystals allows the size of spiky Au NPs to be modulated from tens to several hundreds of nanometers by tuning the concentration of initial Au seeds and Au source; and the thickness of the Ag shell can be adjusted with stepwise reduction of Ag(I) ions. The LSPR bands of such spiky Au@Ag core-shell NPs resemble those of pure spiky Au NP cores of similar sizes in near-infrared region, and increasing the Ag shell thickness results in a blue shift and broadening of the LSPR band in the near-infrared region. Additionally, the spiky Au@Ag core-shell NPs exhibit improved surface-enhanced Raman scattering (SERS) activity as compared to the bare spiky Au NPs and spherical Ag@Au NPs. This work has offered a facile route to synthesize plasmonic metal NPs with LSPR band in 650 to 800 nm that show strong enhancement of localized electromagnetic field, which provides an effective SERS substrate for SERS imaging and detection in biological fluids and tissues.
关键词： localized surface plasmon resonance,gold,silver,surface-enhanced Raman spectroscopy
更新于2025-09-10 09:29:36
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Parathyroid gland management using optical technologies during thyroidectomy or parathyroidectomy: A systematic review
摘要： New optical technologies enhancing localization or assessing viability of parathyroid glands (PG) during endocrine surgery have been reported in clinical studies. These technologies could become complementary to the surgeon’s eyes and may improve surgical outcomes in thyroidectomy and parathyroidectomy. Here, we conducted a systematic review focusing on PG identification and functional assessment using optical methods to enhance surgery. A systematic literature review was performed using MEDLINE and Embase database. Two authors selected studies and extracted data; qualitative analysis was performed to summarize the characteristics of reported optical tools for thyroidectomy or parathyroidectomy. Identification and vascularisation of PG during surgery were evaluated. Clinical and biochemical outcomes were appraised when reported. Studies relating to parathyroidectomy or thyroidectomy combined with autofluorescence, fluorescent methylene blue, 5-aminolevulinic acid, indocyanine green (ICG), optical coherence tomography, laser speckle contrast imaging, dynamic optical contrast imaging and Raman spectroscopy were identified with MEDLINE and Embase. We included a total of 47 relevant articles with a total of 1615 patients enrolled. Each optical technique is described and appreciated related to its surgical purpose. Autofluorescence and ICG imaging of PG are the most widely reported optical technologies for identification and assessment of vascularisation of PG. Results are mainly based on observational studies and argue for the feasibility of both techniques in endocrine surgery but prospective randomized studies have not been performed. In vivo applications are still limited for the other methods and further investigations correlating these techniques with post-operative parathormone measurements are still needed before considering these technologies in clinical practice.
关键词： Surgery,Fluorescence,Dynamic optical contrast imaging,Laser speckle contrast imaging,Optical coherence tomography,Raman spectroscopy,Parathyroid gland
更新于2025-09-10 09:29:36