Fundamentals of ATR-FTIR Spectroscopy and Its Role for Probing In-Situ Molecular-Level Interactions

Kaur, Harsharan; Rana, Bhawna; Tomar, Deepak; Kaur, Sarabjeet; Jena, Kailash C.

doi:10.1007/978-981-33-6084-6_1

Cited by 10 publications

(13 citation statements)

References 93 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Here, ATR-FTIR spectroscopy is employed to extract the molecular-level details of the impact of the NPEI-ONP and dsDNA interaction on their chemical structures in terms of the vibrational signature of the molecules. ATR-FTIR spectroscopy efficiently probes the aqueous solution up to a depth of a few micrometers at the solid–aqueous interface, where it can extract information about the resonant vibrational modes of the functional groups involved in the interaction process. , Figure displays the ATR-FTIR absorption spectra of the NPEI-ONPs, DNA, and their complex in the region of 900–1300 cm –1 , representing the characteristic bands sensitive to the dsDNA backbone conformational changes. − Here, we have conducted the experiments by considering the dsDNA concentration in the higher range (i.e., for 0.03, 0.1, and 1 mg·mL –1 ), as the lower-concentration values of dsDNA were rendering a lower signal-to-noise ratio which was difficult for any conclusive discussion.…”

Section: Resultsmentioning

confidence: 99%

“…The ATR crystal, sample-holding assembly, and all of the glassware used were rigorously washed with isopropanol and deionized water and then subsequently dried. All of the spectra for samples were treated by subtracting the spectrum of pristine water taken initially as a reference, and the resultant data points were smoothed by 13 smoothing number points using the Savitzky–Golay filter algorithm. , The data sets were then subjected to the baseline correction using the concave rubber band correction method, excluding CO 2 bands.…”

Section: Methodsmentioning

confidence: 99%

See 1 more Smart Citation

Elucidating the Molecular Structure of Hydrophobically Modified Polyethylenimine Nanoparticles and Its Potential Implications for DNA Binding

et al. 2022

Self Cite

View full text Add to dashboard Cite

The structural properties of the polyethylenimine (PEI) polymer are generally tuned and selectively modified to reinforce its potential in a broad spectrum of applied domains of medicine, healthcare, material design, sensing, and electronic optimization. The selective modification of the polymer brings about changes in its interfacial characteristics and behavior. The current work involves the synthesis of naphthalimide conjugated polyethylenimine organic nanoparticles (NPEI-ONPs). The interfacial molecular structure of NPEI-ONPs is explored in an aqueous medium at pH 7.4 using surface tensiometry and sum-frequency generation vibrational spectroscopy (SFG-VS). The hydrophobic functionalization rendered a concentration-dependent surface coverage of NPEI-ONPs, where the SFG-VS analysis exhibited the molecular rearrangement of its hydrophobic groups at the interface. The interaction of NPEI-ONPs with double-stranded DNA (dsDNA) is carried out to observe the relevance of the synthesized nanocomposites in the biomedical domain. The bulk-specific studies (i.e., thermal denaturation, viscometry, zeta (ζ) potential, and ATR-FTIR) reveal the condensation of dsDNA in the presence of NPEI-ONPs, making its structure more compact. The interface-sensitive SFG-VS showcased the impact of the dsDNA and NPEI-ONP interaction on the interfacial molecular behavior of NPEI-ONPs at the air–aqueous interface. Our results exhibit the potential of such hydrophobically functionalized ONPs as promising candidates for developing biomedical sealants, substrate coatings, and other biomedical domains.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Elucidating the Molecular Structure of Hydrophobically Modified Polyethylenimine Nanoparticles and Its Potential Implications for DNA Binding

et al. 2022

Self Cite

View full text Add to dashboard Cite

show abstract

“…The spectrum of the modified CS shows increases in the intensity of the amide I, amide II peaks, and those ascribed to C-H bending and stretching confirming modification with methacrylate/pyrrole units. The spectrum for the conductive samples were very broad due to experimental limitations of the technique, including: optical contact between the sample and ATR apparatus, anomalous dispersion [79][80][81], and the fact they are broad band absorbers which resulted in broad spectra as we have observed in previous studies [82]. Solution state 1 H NMR spectra for the CS starting material and the modified CS derivative in DCl/D2O are shown in Figure 3.…”

Section: Scheme 1 Chemical Modification Of Cs (Conjugation Of Methacr...mentioning

confidence: 98%

Electrochemically Enhanced Delivery of Pemetrexed from Electroactive Hydrogels

et al. 2022

View full text Add to dashboard Cite

Electroactive hydrogels based on derivatives of polyethyleneglycol (PEG), chitosan and polypyrrole were prepared via a combination of photopolymerization and oxidative chemical polymerization, and optionally doped with anions (e.g., lignin, drugs, etc.). The products were analyzed with a variety of techniques, including: FT-IR, UV-Vis, 1H NMR (solution state), 13C NMR (solid state), XRD, TGA, SEM, swelling ratios and rheology. The conductive gels swell ca. 8 times less than the non-conductive gels due to the presence of the interpenetrating network (IPN) of polypyrrole and lignin. A rheological study showed that the non-conductive gels are soft (G′ 0.35 kPa, G″ 0.02 kPa) with properties analogous to brain tissue, whereas the conductive gels are significantly stronger (G′ 30 kPa, G″ 19 kPa) analogous to breast tissue due to the presence of the IPN of polypyrrole and lignin. The potential of these biomaterials to be used for biomedical applications was validated in vitro by cell culture studies (assessing adhesion and proliferation of fibroblasts) and drug delivery studies (electrochemically loading the FDA-approved chemotherapeutic pemetrexed and measuring passive and stimulated release); indeed, the application of electrical stimulus enhanced the release of PEM from gels by ca. 10–15% relative to the passive release control experiment for each application of electrical stimulation over a short period analogous to the duration of stimulation applied for electrochemotherapy. It is foreseeable that such materials could be integrated in electrochemotherapeutic medical devices, e.g., electrode arrays or plates currently used in the clinic.

show abstract

“…Attenuated total reflectance infrared (ATR-IR) spectroscopy is a surface-sensitive technique that is commonly used with Fourier transform infrared (FTIR) spectrometers. ATR-IR can provide information on bonding, surface adsorption, surface interactions, molecular orientation/ordering, and reaction kinetics at or near the surface of an ATR crystal, often called an internal reflection element (IRE). − As such, it is a powerful method for understanding interfacial interactions between molecular species and surfaces. In ATR-IR spectroscopy, an IR probe beam is directed into an IRE that is made from a high refractive index ( n ) material such as Si, Ge, ZnSe, or diamond.…”

Section: Introductionmentioning

confidence: 99%

In Situ Attenuated Total Reflectance Infrared Spectroelectrochemistry (ATR-IR-SEC) for the Characterization of Molecular Redox Processes on Surface-Proximal Doped Silicon ATR Crystal Working Electrodes

et al. 2023

View full text Add to dashboard Cite

In situ mid-infrared spectroscopy is a powerful technique for understanding the mechanism of CO2 reduction (CO2R) catalysts because it enables the direct detection of catalytic intermediates and products. Moreover, spectroelectrochemistry (SEC), the coupling of spectroscopy with electrochemistry, allows spectroscopic changes to be correlated with applied potentials to reveal potential-dependent intermediates that are often relevant to photoelectrochemical reactions. Hybrid photoelectrodes, composed of a narrow bandgap semiconductor, like silicon (Si), with a covalently linked molecular catalyst, are a promising platform for sunlight-driven catalysis, but characterization of the catalytic mechanism(s) is challenging under photoelectrochemical conditions, particularly when the catalyst is present in monolayer or less concentrations. Here, we have developed a new strategy to use multiple-reflection attenuated total reflectance IR spectroscopy (ATR-IR) coupled with electrochemistry to characterize catalysts directly integrated with a semiconductor surface under applied potential. We show that by surface-proximal n-type or p-type doping of the top ∼100 to 200 nm of the crystal surface, Si ATR crystals can be used simultaneously as the internal reflection element and semiconductor working electrode for ATR-IR-SEC measurements. The surface-proximal doping strategy yields a quasi-equipotential surface with excellent infrared transparency that would have been compromised by free carrier absorption if the crystal was uniformly doped. This approach permits the catalytically active functionalized surface to be directly probed without modification and overcomes signal-to-noise limitations of other strategies that use separately deposited working electrodes on Si ATR crystals. Proof-of-concept ATR-IR-SEC spectra were collected during the reduction and oxidation of monolayers of Re- and Ru-based transition-metal carbonyl complexes, respectively, verifying the viability of the technique to probe redox processes associated with CO2R catalysts on Si electrode surfaces with high sensitivity.

show abstract

Fundamentals of ATR-FTIR Spectroscopy and Its Role for Probing In-Situ Molecular-Level Interactions

Cited by 10 publications

References 93 publications

Elucidating the Molecular Structure of Hydrophobically Modified Polyethylenimine Nanoparticles and Its Potential Implications for DNA Binding

Elucidating the Molecular Structure of Hydrophobically Modified Polyethylenimine Nanoparticles and Its Potential Implications for DNA Binding

Electrochemically Enhanced Delivery of Pemetrexed from Electroactive Hydrogels

In Situ Attenuated Total Reflectance Infrared Spectroelectrochemistry (ATR-IR-SEC) for the Characterization of Molecular Redox Processes on Surface-Proximal Doped Silicon ATR Crystal Working Electrodes

Contact Info

Product

Resources

About