FIG 1 - uploaded by John Lombardi
Content may be subject to copyright.
Source publication
We evaluated the normal Raman (NR) and the surface-enhanced Raman scattering (SERS) of three sympathomimetic amines: phenethylamine, ephedrine, and 3,4-methylenedioxymethamphetamine (MDMA). In addition, quantum mechanical calculations-geometry optimization and calculations of the harmonic vibrational frequencies-were performed using the density fun...
Similar publications
Rapid component separation and robust surface-enhanced Raman scattering (SERS) identification of drugs in real human urine remain an attractive challenge because of the sample complexity, low molecular affinity for metal surface, and inefficient use of hotspots in one- or two-dimensional (2D) geometries. Here, we developed a five-minute strategy of...
Citations
... The application of density functional theory (DFT) to correlate calculated spectra with experimental data has previously been reported for Raman spectroscopy and surface-enhanced Raman spectroscopy (SERS) [11], as well as forensically relevant compounds, such as fentanyl and its analogs [12,13]. Recently, Wolfe et al. investigated the comparison between experimental Raman data of eleven cannabinoids to simulated spectra from DFT computations [14]. ...
... In 2012, Rolf Wilestone Berg et al [10] conducted a study on the Raman optical activity and Raman spectra of amphetamine species to identify the different enantiomers of amphetamine derivatives. Similarly, in 2013, Francis Taplin et al [11] reported spectroscopic analysis of phenethylamines for the same purpose. Recent studies have focused on the detection of amphetamine using quantum mechanical approaches [12,13]. ...
Accurate structure elucidation of biologically active molecules is crucial for designing and developing new drugs, as well as for analyzing their pharmacological activity. In this study, density functional theory calculations are applied to explore the electronic structure and properties of phenethylamine derivatives, including Amphetamine, Methamphetamine, and Methylene Dioxy Methamphetamine(MDMA). The investigation encompasses various aspects such as geometry optimization, vibrational analysis, electronic properties, Molecular Electrostatic Potential analysis, and local and global descriptor analysis. Additionally, the study utilizes Natural Bond Orbital analysis and Quantum Theory of Atoms in Molecules to investigate the chemical bonding and charge density distributions of these compounds. Experimental techniques such as Fourier transform infrared (FT-IR) and Raman spectroscopic analysis are employed in the range of 4000-400 cm-1 and 4000-50 cm-1, respectively. Theoretical vibrational analysis with Potential Energy Distribution(PED) assignments is conducted, and the resulting frequencies are compared to experimental spectral data, revealing good agreement. By correlating various structural parameters with the pharmacological activity of each derivative, computational structure elucidation aids in understanding the unique actions of phenethylamine derivatives. The obtained results offer a comprehensive understanding of the molecular behavior and properties of these drugs, facilitating the development of new drugs and therapies for addiction and related disorders.
... for the detection of drugs acting on the central nervous system such as phenethylamine, epinephrine, 3,4methylenedioxymethamphetamine having a wide application in forensic science. Almost similar results have been obtained with Raman spectra obtained from both the spectroscopic tools and those predicted using Density Functional Theory (DFT) [82] . Such techniques can be utilized for the prediction of a large number of compounds for forensic applications. ...
... Likewise, as shown in Fig. 7c, the main peaks that appeared at 525 cm -1 , 715 cm -1 , 810 cm -1 , 1245 cm -1 , 1365 cm -1 , 1435 cm -1 , and 1490 cm -1 agree with those of silver colloids excited at 514 nm, but not at 633 nm and 1064 nm. 44 These SERS peaks were detectable at trace concentrations down to 52 µM after wetting with water ( Fig. 7c) and at 0.52 mM in a methanol solution (Fig. 7d), while no Raman peak of MDMA at a trace concentration of 0.52 mM on a silicon substrate was obtained with the same laser Raman microscope. 13 These results indicate the superior capability of Place & Play SERS in nondestructive, real-time, in situ Raman-based forensic analysis. ...
The ability to perform sensitive, real-time, in situ, multiplex chemical analysis is indispensable for diverse applications such as human health monitoring, food safety testing, forensic analysis, environmental sensing, and homeland security. Surface-enhanced Raman spectroscopy (SERS) is an effective tool to offer the ability by virtue of its high sensitivity and rapid label-free signal detection as well as the availability of portable Raman spectrometers. Unfortunately, the practical utility of SERS is limited because it generally requires sample collection and preparation, namely, collecting a sample from an object of interest and placing the sample on top of a SERS substrate to perform a SERS measurement. In fact, not all analytes can satisfy this requirement because the sample collection and preparation process may be undesirable, laborious, difficult, dangerous, costly, or time-consuming. Here we introduce "Place & Play SERS" based on an ultrathin, flexible, stretchable, adhesive, biointegratable gold-deposited polyvinyl alcohol (PVA) nanomesh substrate that enables placing the substrate on top of an object of interest and performing a SERS measurement of the object by epi-excitation without the need for touching, destroying, and sampling it. Specifically, we characterized the sensitivity of the gold/PVA nanomesh substrate in the Place & Play SERS measurement scheme and then used the scheme to conduct SERS measurements of both wet and dry objects under nearly real-world conditions. To show the practical utility of Place & Play SERS, we demonstrated two examples of its application: food safety testing and forensic analysis. Our results firmly verified the new measurement scheme of SERS and are expected to extend the potential of SERS by opening up untapped applications of sensitive, real-time, in situ multiplex chemical analysis.
... , 1365 cm -1 , 1435 cm -1 , and 1490 cm -1 agree with those of silver colloids excited at 514 nm, but not at 633 nm and 1064 nm.39 These peaks were detectable at trace concentrations down to 52 µM after wetting with water ...
The ability to perform sensitive, real-time, in situ, multiplex chemical analysis is indispensable for diverse applications such as human health monitoring, food safety testing, forensic analysis, environmental sensing, and homeland security. Surface-enhanced Raman spectroscopy (SERS) is an effective tool to offer the ability by virtue of its high sensitivity and rapid label-free signal detection as well as the availability of portable Raman spectrometers. Unfortunately, the practical utility of SERS is limited because it generally requires sample collection and preparation, namely, collecting a sample from an object of interest and placing the sample on top of a SERS substrate to perform a SERS measurement. In fact, not all analytes can satisfy this requirement because the sample collection and preparation process may be undesirable, laborious, difficult, dangerous, costly, or time-consuming. Here we introduce "Place & Play SERS" based on an ultrathin, flexible, stretchable, adhesive, biointegratable gold-deposited polyvinyl alcohol (PVA) nanomesh substrate that enables placing the substrate on top of an object of interest and performing a SERS measurement of the object by epi-excitation without the need for touching, destroying, and sampling it. Specifically, we characterized the sensitivity of the gold/PVA nanomesh substrate in the Place & Play SERS measurement scheme and then used the scheme to conduct SERS measurements of both wet and dry objects under nearly real-world conditions. To show the practical utility of Place & Play SERS, we demonstrated two practical applications: food safety testing and forensic analysis. Our results firmly verified the new measurement scheme of SERS and are expected to extend the potential of SERS by opening up untapped applications of sensitive, real-time, in situ multiplex chemical analysis.
... The primary library spectra were collected, and baseline corrected are shown below in and are consistent with the SERS spectra and vibrational assignments that have been reported previously in the literature for these drugs. [35,40,45,53,55,[64][65][66][67][68] Each one of these drugs produce a unique SERS spectrum that are included in our library database for automatic identification. Figure 2 shows the SERS spectra of seven representative drugs of concern that are classified as stimulants. ...
... This absence can be attributed to the constraints of the dioxole ring structure imposed on the inplane ring breathing mode. [68] Although the Raman of MBDB has been reported, [66] this is the first time as far as we can determine that the SERS has been reported for MBDB. Figure 3 shows the SERS spectra of the five opioids that were measured in this study. A dominant characteristic peak at 624 cm À1 (C CH out-of-plane ring bending mode) and strong unique peaks are observed at 920 and 1242 cm À1 for heroin. ...
Surface‐enhanced Raman spectroscopy (SERS) is a rapidly emerging technology that offers a fast, extremely sensitive, and quantitative approach to trace chemical detection. Such a technique incorporated into a portable device is attractive to law enforcement and emergency room personnel for rapid accurate on‐site screening of illicit and abused drugs. Toward this we are developing an analyzer in a hand‐held unit, based on SERS that is integrated with a capillary sensor embedded with activated gold nanoparticles in a porous glass matrix. In this preliminary study we have used this gold sol‐gel capillary to measure aqueous solutions of 14 high‐priority drugs to define sensitivity (lowest measured concentration (LMC) and estimated limit of detection (LOD)), determine concentration dependence and quantification capabilities by constructing calibration curves, examine effects of pH at 3, 7 and 11 on SERS measurements, and perform multicomponent analysis of fentanyl laced drug mixtures and spectral identification on our portable and handheld units. Of particular significance fentanyl was detected with an LMC of 1 ng/mL and estimated LOD at 0.11 ng/mL, while other representative drugs such as cocaine and phenylcyclidine produced LMCs and LODs at 5.0 and 0.77 ng/mL, and 10.0 and 0.62 ng/mL respectively. These sub ng/mL detection limits are comparable or lower than previously reported and confirm that this gold sol‐gel has the potential to meet the sensitivity requirements for saliva analysis. Most importantly, these sensors can be manufactured easily and cheaply, and when integrated with our portable Raman units produce high‐quality spectra and accurate identification within 1.2 sec.
... While the PEA molecules contain phenethyl complexes that are expected to be relatively rigid, BA spacer molecules consist of a linear alkyl chain that is soft and more flexible. Therefore, torsional and bending oscillations of the molecules, 41 can be seen from the optical microscopy images in Figure S2. The X-ray diffraction patterns and optical characterization of the flakes are given in Figure S1 of the Supporting Information (SI), and show that the (001) planes are parallel to the substrate, with a spacing of 1.4 nm and 1.7 nm of the octahedral layers for (BA)2PbBr4 and (PEA)2PbBr4, respectively. ...
The vibrational modes in organic/inorganic layered perovskites are of fundamental importance for their optoelectronic properties. The hierarchical architecture of the Ruddlesden-Popper phase of these materials allows for distinct directionality of the vibrational modes withrespect to the main axes of the pseudocubic lattice in the octahedral plane. Here, we study the directionality of the fundamental phonon modes in single exfoliated Ruddlesden-Popper perovskite flakes with polarized Raman spectroscopy at ultralow-frequencies. A wealth of Raman bands is distinguished in the range from 15-150 cm-1 (2-15 meV), whose features depend on the organic cation species, on temperature, and on the direction of the linear polarization of the incident light. By controlling the angle of the linear polarization of the excitation laser with respect to the in-plane axes of the octahedral layer, we gain detailed information on the symmetry of the vibrational modes. The choice of two different organic moieties, phenethylammonium (PEA) and butylammonium (BA) allows to discern the influence of the linker molecules, evidencing strong anisotropy of the vibrations for the (PEA)2PbBr4 samples. Temperature dependent Raman measurements reveal that the broad phonon bands observed at room temperature consist of a series of sharp modes, and that such mode splitting strongly differs for the different organic moieties and vibrational bands.
... While the PEA molecules contain phenethyl complexes that are expected to be relatively rigid, BA spacer molecules consist of a linear alkyl chain that is soft and more flexible. Therefore, torsional and bending oscillations of the molecules, 41,42 induced by the vibrations of the inorganic lattice, are more pronounced in the PEA flakes, as confirmed by density functional theory (DFT) calculations. From the as-synthesized 2D layered perovskite materials single flakes (Figure 2b) can be exfoliated by using the scotch tape exfoliation technique (see Methods). ...
The vibrational modes in organic/inorganic layered perovskites are of fundamental importance for their optoelectronic properties. The hierarchical architecture of the Ruddlesden-Popper phase of these materials allows for distinct directionality of the vibrational modes with respect to the main axes of the pseudocubic lattice in the octahedral plane. Here, we study the directionality of the fundamental phonon modes in single exfoliated Ruddlesden-Popper perovskite flakes with polarized Raman spectroscopy at ultralow-frequencies. A wealth of Raman bands is distinguished in the range from 15-150 cm-1 (2-15 meV), whose features depend on the organic cation species, on temperature, and on the direction of the linear polarization of the incident light. By controlling the angle of the linear polarization of the excitation laser with respect to the in-plane axes of the octahedral layer, we gain detailed information on the symmetry of the vibrational modes. The choice of two different organic moieties, phenethylammonium (PEA) and butylammonium (BA) allows to discern the influence of the linker molecules, evidencing strong anisotropy of the vibrations for the (PEA)2PbBr4 samples. Temperature dependent Raman measurements reveal that the broad phonon bands observed at room temperature consist of a series of sharp modes, and that such mode splitting strongly differs for the different organic moieties and vibrational bands. Softer molecules such as butylammonium result in lower vibrational frequencies and splitting into fewer modes, while more rigid molecules such as PEA lead to higher frequency oscillations and larger number of Raman peaks at low temperature. Interestingly, in distinct bands the number of peaks in the Raman bands is doubled for the rigid PEA compared to the soft BA linkers. Our work shows that the coupling to specific vibrational modes can be controlled by the incident light polarization and choice of the organic moiety, which could be exploited for tailoring exciton-phonon interaction, and for optical switching of the optoelectronic properties of such 2D layered materials.
... In terms of applicability, Au and Ag being more stable are popular as compared to Cu which is more reactive. Chemically prepared Au and Ag colloids are reported to drastically enhance the Raman signal of various analytes such as alpha-tocopherol and phenethylamines, having weak Raman signal [13,14]. But the low cost and applicability of Cu NPs as catalyst and in various biochemical applications has motivated many researchers to use Cu as an effective SERS substrate [15][16][17]. ...
... SERS has been employed for the identification of trace identification of certain controlled substances. The drugs previously examined have included amphetamines [18][19][20][21][22][23], opiates [19,20,24,25], benzodiazepines [26][27][28], and designer drugs [29,30]. ...
Synthetic cannabinoids (K2, spice) present problems in forensic investigations because standard presumptive methods, such as immunoassays, are insufficiently specific for the wide range of potential target compounds. This issue can lead to problems with low sensitivity and yield false negative results. A potential solution to this problem is surface enhanced Raman spectroscopy (SERS). In this study we demonstrate the analysis of a set of structurally similar synthetic cannabinoids using SERS. The procedure involves mixing the analyte with gold nanoparticles prepared in a solution containing alkali or alkaline earth salt solutions. The salts produce aggregation of the nanoparticles with a resultant spectral enhancement due to the formation of spectral hotspots with enhanced field effects within the aggregate. Among the salts tested, 0.0167 M MgCl2 produced the lowest limit of detection and best overall sensitivity. The method produces clearly distinguishable spectra for each synthetic cannabinoid with detection limits as low as 18 ng/mL. Spiked urine samples were also analyzed following a cleanup procedure involving support liquid extraction. When using a portable Raman system, a higher concentration of MgCl2 was needed to produce similar a LOD. The results demonstrate that this procedure has great potential as a method for presumptive screening of synthetic cannabinoids.
