Raman Spectroscopy Research Articles

Synthesis of Self-Assembled Nanostructured Cisplatin Using the RESS Process

Background/Objectives: The primary goal of our research is to develop a process to prepare an aqueous dispersion of Cisplatin, an important anticancer drug, with increased solubility and storage stability. Method: In this context, we report the use of a customized RESS process for the synthesis of a novel, amber-colored and viscous aqueous cisplatin solution, an important anticancer drug, which we have denoted as “liquid” cisplatin. Results: Using specialized liquid cell in situ transmission electron microscopy (Liquid in situ TEM) and Raman spectroscopy, we demonstrated that “liquid” cisplatin comprises a bi-modal distribution of a highly solvated network of stable cisplatin nanoclusters in water and exhibited 27 times greater water solubility than standard cisplatin. More importantly, “liquid” cisplatin was stable at ambient conditions for over two years. Extensive analytical characterization of “liquid” cisplatin confirmed that it retained the original chemical identity of cisplatin. Cell viability and apoptosis studies on human lung adenocarcinoma A549 cells provided compelling evidence that “liquid” cisplatin demonstrated a more sustained anticancer effect compared to standard cisplatin. Conclusions: Aqueous cisplatin solubility was increased by 27X in the “liquid” cisplatin medium which retained its bio efficacy over a 2-year period. Our experimental results suggest the possibility of developing non-invasive and highly effective novel cisplatin drug-delivery platforms.

Retraction of “Bisboronic Acids for Selective, Physiologically Relevant Direct Glucose Sensing with Surface-Enhanced Raman Spectroscopy”

Retraction of “Bisboronic Acids for Selective, Physiologically Relevant Direct Glucose Sensing with Surface-Enhanced Raman Spectroscopy”

Online coupling of size exclusion chromatography to capillary-enhanced Raman spectroscopy for the identification of protein classes in hemolyzed blood serum

Online coupling of size exclusion chromatography to capillary-enhanced Raman spectroscopy for the identification of protein classes in hemolyzed blood serum

Designing structures that maximize spatially averaged surface-enhanced Raman spectra: erratum

Designing structures that maximize spatially averaged surface-enhanced Raman spectra: erratum

In-Plane Chirality Control of a Charge Density Wave by Means of Shear Stress.

The transition metal dichalcogenide 1T-TaS2 exhibits a Charge Density Wave(CDW) with in-plane chirality. Due to the rich phase diagram, the Ferro-Rotational Order (FRO) can be tuned by external stimuli. The FRO is studied by Angle-Resolved Photoelectron Spectroscopy (ARPES), Raman spectroscopy, and Selected Area Electron Diffraction (SAED). The in-plane chirality of the CDW is lost at the transition from Nearly-Commensurate (NC) to In-Commensurate (IC) phase and can be controlled by applying shear stress to the sample while cooling it through the transition from IC-CDW to NC-CDW. Based on these observations, a protocol is proposed to achieve reliable, non-volatile state switching of the FRO configuration in 1T-TaS2 bulk crystals. These results pave the way for new functional devices in which in-plane chirality can be set ondemand.

Active plasmonic nanodevices: From basic principles to emerging applications

AbstractTunable plasmonics has shown a wide range of applications in (bio)chemical sensing, displays, actuators, photonic chips, biomedicine, etc. in the last 2 decades. This review focuses on their recent development from the device perspective, which involves the understanding of fundamental principles and specific applications with desired functionality and compatibility. We classify these active plasmonic devices based on the nature of their structures and working environment as colloidal‐based, chip‐based, and colloidal chip‐based to further elaborate their performance and functions. We also highlight recent progress on tunable surface‐enhanced Raman spectroscopy, metasurfaces, and chiroptics to show the emerging applications of tunable plasmonic systems. We conclude this review with a general perception of the research trend in this field and challenges for their practical applications.

Shell-Isolated Nanoparticle-Enhanced Raman Spectroscopy: Toward High Sensitivity and Broad Applicability.

As a nondestructive and ultrasensitive technique, surface-enhanced Raman spectroscopy (SERS) has captivated the attention of the global scientific community for over 50 years. Among the various spectroscopic techniques derived from SERS, shell-isolated nanoparticle-enhanced Raman spectroscopy (SHINERS) stands as a cutting-edge advancement. The innovative and versatile core-shell nanoparticle structures used in SHINERS have emerged as an ideal platform for interfacial research, offering high sensitivity and broad applicability across diverse materials and single-crystal surfaces. Consequently, SHINERS has seen widespread adoption in pivotal fields, such as interface chemistry, electrocatalysis, biomedicine, materials, and food safety. In this Perspective, we outline the evolutionary journey of SHINERS, delve deep into its applications in fundamental research for interface characterization and catalysis, and explore its practical utility in critical areas of food safety and biomedicine analysis. Additionally, we map out the prospective trajectory and future milestones that await SHINERS as it continues to revolutionize the landscape of scientific exploration.

Single-Entity Electrochemistry of N-Doped Graphene Oxide Nanostructures for Improved Kinetics of Vanadyl Oxidation.

N-doped graphene oxides (GO) are nanomaterials of interest as building blocks for 3D electrode architectures for vanadium redox flow battery applications. N- and O-functionalities have been reported to increase charge transfer rates for vanadium redox couples. However, GO synthesis typically yields heterogeneous nanomaterials, making it challenging to understand whether the electrochemical activity of conventional GO electrodes results from a sub-population of GO entities or sub-domains. Herein, single-entity voltammetry studies of vanadyl oxidation at N-doped GO using scanning electrochemical cell microscopy (SECCM) are reported. The electrochemical response is mapped at sub-domains within isolated flakes and found to display significant heterogeneity: small active sites are interspersed between relatively large inert sub-domains. Correlative Raman-SECCM analysis suggests that defect densities are not useful predictors of activity, while the specific chemical nature of defects might be a more important factor for understanding oxidation rates. Finite element simulations of the electrochemical response suggest that active sub-domains/sites are smaller than the mean inter-defect distance estimated from Raman spectra but can display very fast heterogeneous rate constants >1cms-1. These results indicate that N-doped GO electrodes can deliver on intrinsic activity requirements set out for the viable performance of vanadium redox flow battery devices.

Enhancement of the Photoluminescent Intensity of YVO4: Er, Yb UCNPs Using a Simple Coprecipitation Synthesis Method.

Yttrium vanadate (YVO4) is a non-toxic ceramic matrix that, when doped with lanthanides, can be used as a photoluminescent biosensor. In this study, we meticulously synthesized upconversion nanoparticles (UCNPs) of YVO4 via chemical coprecipitation, using Er3+ and Yb3+ ions for codoping. The light emission achieved through upconversion mechanisms enables the excitation of nanoparticles with infrared light rather than ultraviolet light, enhancing the potential of current bioimaging techniques. The light emission intensity of our YVO4: Er, Yb UCNPs, a key factor in their effectiveness, depended on various easily adjustable factors during the synthesis, such as the dopant concentration, the heat treatment, and the cleaning process. The UCNPs were characterized using a range of advanced techniques, including X-ray diffraction (XRD) and Rietveld refinements, as well as Raman, photoluminescence (PL), and ultraviolet-visible (UV-vis) spectroscopies, and high-resolution transmission electron microscopy (HRTEM). We found the most convenient stoichiometry to obtain the YVO4: Er, Yb UCNPs and showed that a rigorous thermal treatment was necessary to achieve light emission through upconversion mechanisms. We also discovered that some porosity characteristics can be promoted in the YVO4: Er, Yb UCNPs during the cleaning process, depending on the solvent employed. The porosity and morphology of the nanoparticles could be predicted using the microstrain values obtained from the refinement of the crystalline structures. All these meticulous steps in our research have enabled us to develop an efficient synthesis pathway to produce YVO4: Er, Yb UCNPs with high photoluminescent intensity.

Raman Handheld Versus Microscopic Spectroscopy for Estimating the Post-Mortem Interval of Human Bones: A Comparative Pilot Study

The post-mortem interval estimation for human skeletal remains is critical in forensic medicine. This study used Raman spectroscopy, specifically comparing a handheld device to a Raman microscope for PMI estimations. Analyzing 99 autopsy bone samples and 5 archeological samples, the research categorized them into five PMI classes using conventional methods. Key parameters—like ν1PO43− intensity and crystallinity—were measured and analyzed. A principal component analysis effectively distinguished between PMI classes, indicating high classification accuracy for both devices. While both methods proved reliable, the fluorescence interference presented challenges in accurately determining the age of archeological samples. Ultimately, the study highlighted how Raman spectroscopy could enhance PMI estimation accuracy, especially in non-specialized labs, suggesting the potential for improved device optimization in the field.

Effects of Al Substitution for Fe in Na₅FeSi₄O₁₂ (5.1.8) Glasses: Structure and Crystallization

In this study, the effects of substituting Al for Fe in 5Na2O∙(Al2O3)x∙(Fe2O3)1-x∙8SiO2 glass, x=0 to 1, and Na5AlxFe1-xSi4O12 (5.1.8) crystal, were investigated using thermal analysis, Fe K-edge X-ray absorption, X-ray diffraction, Raman spectroscopy, and Electron Probe Microanalysis. In both glass and crystallized glass, nearly all the Fe was tetrahedrally coordinated Fe3+, as expected from the high concentration of Na2O. The substitution of Al for Fe in the glasses caused the glass transition temperature to increase as polymerization increased, as evidenced by Raman, likely due to both field strength differences of Al vs Fe and a small amount of Fe2+ network modifier present with Fe. After heat treatment at 700 °C for 24 hours, the glasses had crystallized, forming Na2SiO3 and NaAlSiO4 in compositions with high Al concentrations and the 5.1.8 crystal in compositions with high Fe concentrations. Through electron microprobe, it was determined that <0.04 formula unit Al incorporated into the 5.1.8 crystal, i.e. Na5Fe0.96Al0.04Si4O12. The 5.1.8 crystal only formed when Fe concentration was higher than Al in the starting glass.

Precise Genotyping Via Surface‐Enhanced Raman Spectroscopy‐Based Optical Sensing Chip for Guiding Targeted Therapy in Lung Cancer

AbstractThe emergence of “precision medicine” marks a notable shift in cancer treatment, moving from a tumor type–oriented approach to a more targeted, gene‐oriented approach. Detecting low‐abundance mutant genes in blood is challenging but crucial for personalized treatment plans. Herein, a novel platform combining catalytic hairpin self‐assembly (CHA)‐mediated self‐calibrating surface‐enhanced Raman spectroscopy (SERS) with a high‐throughput Raman system (CCSPS) was designed. This platform enables ultrasensitive and rapid genotype analysis of gene mutations. The development of CCSPS specifically targets EGFR mutations, which serve as crucial therapeutic targets for precision therapy in lung cancer. This system shows excellent sensitivity and selectivity, capable of detecting multiple EGFR mutations (Del‐19, L858R, and T790M) with a detection limit as low as attomolar levels. Additionally, precise genotyping analysis was successfully conducted on 42 clinical samples using the CCSPS, yielding results consistent with those obtained through next‐generation sequencing. These results underscore the efficacy of the CCSPS in noninvasively identifying circulating tumor DNA (ctDNA) mutations, facilitating immediate therapeutic decision making at the bedside. In summary, the CCSPS is a fast, accurate, versatile, and compact testing system capable of precisely screening individuals who stand to benefit from targeted therapy, thus promoting personalized and precise healthcare.

Electronic, optical, elastic, piezoelectric and vibrational properties of P63 KLiSO4

Abstract KLiSO4 of the P63 symmetry is a well refined crystal at room temperature, which is a pyroelectric material with a large second harmonic generation response. However, its fundamental physical properties are still not well studied. In this work, first principles calculations are performed to study its electronic, optical, elastic, piezoelectric and vibrational properties. The results indicate that it is an ionic crystal with a large indirect band gap. Calculated optical properties imply that P63 KLiSO4 has little optical anisotropy at low frequencies. Obtained elastic constants reveal that it is mechanically stable but anisotropic, as illustrated by the directional bulk and shear moduli. Piezoelectric coefficients, dielectric constants, and Born effective charges (BECs) are computed using the density functional perturbation method. Studies disclose that it has a greater piezoelectric coefficient along the c axis. The ions have more contribution to the total dielectric constants than the electrons. The S atoms have the largest BECs. The phonon vibrational modes at the Brillouin zone center are analyzed by the factor group theory. Its infrared and Raman spectra are simulated. The causation for the vanishment of some infrared peaks in the computed infrared spectrum is uncovered. Additionally, elastic related moduli, hardness, melting point and electromechanical coupling coefficients of P63 KLiSO4 are also predicated.

From Bulk to Surface: A Raman Spectroscopic Analysis of Solvation Structures in Concentrated Acetonitrile Electrolytes for Li–O2 Batteries

From Bulk to Surface: A Raman Spectroscopic Analysis of Solvation Structures in Concentrated Acetonitrile Electrolytes for Li–O₂ Batteries

In Situ Raman Study of Layered Double Hydroxide Catalysts for Water Oxidation to Hydrogen Evolution: Recent Progress and Future Perspectives

With the increasing global emphasis on green energy and sustainable development goals, the electrocatalytic oxygen evolution reaction (OER) is gradually becoming a crucial focus in research on water oxidation for hydrogen generation. However, its complicated reaction processes associated with its high energy barrier severely limit the efficiency of energy conversion. Recently, layered double hydroxide (LDH) has been considered as one of the most promising catalysts in alkaline media. Nonetheless, lacking a deep insight into the kinetic process of the electrocatalytic OER process is detrimental to the further optimization of LDH catalysts. Therefore, monitoring the catalytic reaction kinetic process via surface-sensitive in situ spectroscopy is especially important. In particular, the in situ Raman technique is capable of providing fingerprint information for surface species and intermediates in the operating environment. From the perspective of Raman spectroscopy, this paper provides an exhaustive overview of research progress in in situ Raman for the characterization of the catalytic mechanism of LDH catalysts, providing theoretical guidance for designing LDH materials. Finally, we present an incisive discussion on the challenges of the electrocatalytic in situ Raman technique and its future development trend.

Design and fabrication of a dual laser Raman spectrometer with a single one-dimensional CCD detector.

The combination of two spectrometers in dual-laser Raman devices without the need for moving parts represents a significant advancement. This study focuses on design and fabrication of a dual spectrometer with no moving components, allowing data to be gathered using a single detector. This instrument consists of two Czerny-Turner optical arrangements which is symmetrically merged. Dual spectrometer single detector has two light inputs, each of them, concentrating the light separately on a one linear charge-coupled device detector through two independent optical paths. In this innovative spectrometer design, no optical moving parts are used, and therefore, the wavelength displacement error in repeating the spectroscopic experiment is zero. The independent nature of the optical paths enables the optimization of each spectrometer arrangement without affecting the other. The final spectrometer has a spectral resolution of 4.6 and 6.11cm- 1 for Full Width at Half Maximum across the wavelength ranges of 532 to 708nm and 784.65 to 1100nm, respectively. Switching between the two different acquisition setups can be done seamlessly and quickly, with the ability to record approximately 2000 spectra per second. Standard neon and mercury-argon lamps' atomic radiation spectra, along with Raman scattering data from a cyclohexane standard sample, were successfully recorded using laser wavelengths of 532nm and 784.65nm.

Optimizing Carbon Structures in Laser-Induced Graphene Electrodes Using Design of Experiments for Enhanced Electrochemical Sensing Characteristics.

In this study, we explored the morphological and electrochemical properties of carbon-based electrodes derived from laser-induced graphene (LIG) and compared them to commercially available graphene-sheet screen-printed electrodes (GS-SPEs). By optimizing the laser parameters (average laser power, speed, and focus) using a design of experiments response surface (DoE-RS) approach, binder-free LIG electrodes were achieved in a single-step process. Traditional trial-and-error methods can be time-consuming and may not capture the interactions between all variables effectively. To address this, we focused on linear resistance and substrate delamination to streamline the DoE-RS optimization process. Two LIGs, designated LIG A and LIG B, were fabricated using distinct and optimized laser settings, which resulted in a sheet resistance of 25 ± 2 Ω/sq and 21 ± 1 Ω/sq, respectively. These LIGs, characterized by scanning electron microscopy, Raman spectroscopy, and contact angle analysis, exhibited a highly porous morphology with 13% pore coverage and a contact angle <50°, which significantly increased their hydrophilicity when compared to the GS-SPE. For the electrochemical studies, the oxidation of NO2- ion by the graphene-based working electrodes was investigated, as it allowed for the direct comparison of the LIGs to the GS-SPE. These included cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulsed voltammetry studies, which revealed that LIG electrodes displayed a remarkable 500% increase in peak current during NO2- oxidation compared to the GS-SPE. The LIGs also demonstrated improved stability and sensitivity (420 ± 30 and 570 ± 10 nAμM-1 cm-2) compared to the GS-SPE (73 ± 4 nAμM-1 cm-2) in the oxidation of NO2- ions; however, LIG B was more susceptible to ionic interference than LIG A. These findings highlight the value of applying statistical approaches such as DoE-RS to systematically improve the LIG fabrication process, enabling the rapid production of optimized LIGs that outperform conventional carbon-based electrodes.

Microfluidics for studying the deep underground biosphere: from applications to fundamentals.

In this review, selected examples are presented to demonstrate how microfluidic approaches can be utilized for investigating microbial life from deep geological environments, both from practical and fundamental perspectives. Beginning with the definition of the deep underground biosphere and the conventional experimental techniques employed for these studies, the use of microfluidic systems for accessing critical parameters of deep life in geological environments at the microscale is subsequently addressed (high pressure, high temperature, low volume). Microfluidics can simulate a range of environmental conditions on a chip, enabling rapid and comprehensive studies of microbial behavior and interactions in subsurface ecosystems, such as simulations of porous systems, interactions among microbes/microbes/minerals, and gradient cultivation. Transparent microreactors allow real-time, noninvasive analysis of microbial activities (microscopy, Raman spectroscopy, FTIR microspectroscopy, etc.), providing detailed insights into biogeochemical processes and facilitating pore-scale analysis. Finally, the current challenges and opportunities to expand the use of microfluidic methodologies for studying and monitoring the deep biosphere in real time under deep underground conditions are discussed.

Towards Bacterial Resistance via the Membrane Strategy: Enzymatic, Biophysical and Biomimetic Studies of the Lipid cis-trans Isomerase of Pseudomonas aeruginosa.

The lipid cis-trans isomerase (Cti) is a periplasmic heme-c enzyme found in several bacteria including Pseudomonas aeruginosa, a pathogen known for causing nosocomial infections. This metalloenzyme catalyzes the cis-trans isomerization of unsaturated fatty acids in order to rapidly modulate membrane fluidity in response to stresses that impede bacterial growth. As a consequence, breakthrough in the elucidation of the mechanism of this metalloenzyme might lead to new strategies to combat bacterial antibiotic resistance. We report the first comprehensive biochemical, electrochemical and spectroscopic characterization of a Cti enzyme. This has been possible by the successful purification of Cti from P. aeruginosa (Pa-Cti) in favorable yields with enzyme activity of 0.41 µmol/min/mg when tested with palmitoleic acid. Through a synergistic approach involving enzymology, site-directed mutagenesis, Raman spectroscopy, Mössbauer spectroscopy and electrochemistry, we identified the heme coordination and redox state, pinpointing Met163 as the sixth ligand of the FeII of heme-c in Pa-Cti. Significantly, the development of an innovative assay based on liposomes demonstrated for the first time that Cti catalyzes cis-trans isomerization directly using phospholipids as substrates without the need of protein partners, answering the important question about the substrate of Cti within the bacterial membrane.

Achieving High Photocatalytic NOx Removal Activity Using a Bi/BiOBr/TiO2 Composite Photocatalyst.

Fossil fuel combustion generates nitrogen oxides (NO + NO2 = NOx), which pose threats to the environment and human health. Although commercial products containing titanium dioxide (TiO2) can remedy NOx pollution by photocatalysis, they only function in the ultraviolet (UV). On the other hand, bismuth oxybromide (BiOBr) is active in the visible. BiOBr is stable, affordable, and non-toxic, making it an appealing alternative. In addition, nanoparticulate Bi metal can further enhance visible light absorption through its surface plasmon properties and charge carrier lifetime by spatially separating charge. In this study, to enhance the visible-light activity of TiO2-based photocatalysts for NOx pollution, a composite of Bi-decorated BiOBr/TiO2 was synthesized using a solvothermal method across varying the Ti/Bi atomic ratio (0.2, 2.2, 4.4, and 6.6), and synthesis duration (6h, 12h, and 18h). The photocatalytic performance of the synthesised composites for NO gas removal was investigated using an adapted ISO method (22197-1:2016). Analysis showed that the preferential growth of the (010) crystal facet in BiOBr and the presence of Bi metal both play an important role in the superior photocatalytic activity seen in our Bi-decorated BiOBr/TiO2 composite. The composites were characterised using X-ray diffraction (XRD), attenuated total reflectance - Fourier transform infrared spectroscopy (ATR-FTIR), high-resolution scanning electron microscopy (HRSEM), UV-Vis diffuse reflectance (DRS) spectroscopy, transmission electron microscopy (TEM), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Brunauer-Emmett-Teller (BET) analysis, thermogravimetric analysis (TGA), and diffuse reflectance transient absorption spectroscopy (DR-TAS). Our research shows that the Bi/BiOBr-TiO2 composite synthesised through the 12-hour solvothermal method with a Ti/Bi atomic ratio of 4.4 exhibits the highest photocatalytic performance towards both NO and NO2 oxidation; with 32.8% and 54.9% NO removal and 15.1% and 29.5% NO2 under visible and UV lamps, respectively.