Spectroscopic Imaging at the Nanoscale: Technologies and Recent Applications

Xiao, Lifu; Schultz, Zachary D.

doi:10.1021/acs.analchem.7b04151

Cited by 82 publications

(50 citation statements)

References 231 publications

(452 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Vibrational spectroscopic techniques, infra-red and Raman spectroscopy, allow the continuous monitoring of APIs during processing which helps to evaluate the effect of formulation variables on the final product performance. 67,68 Recently, vibrational spectroscopy techniques have been employed in tablet dissolution studies in order to obtain a better understanding of the process of drug release from pharmaceutical formulations and to monitor drug distribution within it. 69,70 Since the Raman intensity of water is very weak compared to IR, 71 Raman spectroscopy was chosen to monitor MS distribution between the dry core region and the hydrated gel layer during the time of swelling/dissolution.…”

Section: Evaluation Of Drug Distribution During Dissolution Using Rammentioning

confidence: 99%

Elucidation of the Controlled-Release Behavior of Metoprolol Succinate from Directly Compressed Xanthan Gum/Chitosan Polymers: Computational and Experimental Studies

Dadou

El‐Barghouthi

Antonijević

et al. 2019

ACS Biomater. Sci. Eng.

View full text Add to dashboard Cite

The development and evaluation of a controlled-release (CR) pharmaceutical solid dosage form comprising xanthan gum (XG), low molecular weight chitosan (LCS) and metoprolol succinate (MS) is reported. The research is, partly, based upon the utilization of computational tools; in this case molecular dynamics simulations (MDs) and response surface method (RSM), in order to underpin the design/prediction and to minimize the experimental work required to achieve the desired pharmaceutical outcomes. The capability of the system to control the release of MS was studied as a function of LCS (% w/w) and total polymer (LCS and XG) to drug ratio (P:D) at different tablet tensile strengths. MDs trajectories, obtained by using different ratios of XG:LCS as well as XG and high molecular weight CS (HCS), showed that the driving force for the interaction between XG and LCS is electrostatic in nature, the most favourable complex is formed when LCS is used at 15 % (w/w) and, importantly, that the interaction between XG and LCS is more favourable than that between XG and HCS. RSM outputs revealed that the release of the drug from the LCS/XG matrix is highly dependent on both the % LCS and the P:D ratio and that the required CR effect can be achieved when using weight fractions of LCS ≤ 20% and P:D ratios ≥ 2.6:1. Results obtained from in-vitro drug release and swelling studies on the prepared tablets showed that using LCS at the weight fractions suggested by MDs and RSM data plays a major role in overcoming the high sensitivity of the controlled drug release effect of XG on ionic strength and pH changes of the dissolution media. In addition, it was found that polymer relaxation is the major contributor to the release of MS from LCS-XG tablets. Using Raman spectroscopy, MS was shown to be localized more in the core of the tablets at the initial stages of dissolution due to film formation between LCS and XG on the tablet surface which prevents excess water penetration into the matrix. In the later stages of the dissolution process, the film starts to dissolve/erode allowing full tablet hydration and a uniform drug distribution in the swollen tablet.

show abstract

Section: Evaluation Of Drug Distribution During Dissolution Using Rammentioning

confidence: 99%

Elucidation of the Controlled-Release Behavior of Metoprolol Succinate from Directly Compressed Xanthan Gum/Chitosan Polymers: Computational and Experimental Studies

Dadou

El‐Barghouthi

Antonijević

et al. 2019

ACS Biomater. Sci. Eng.

View full text Add to dashboard Cite

show abstract

“…Furthermore, PTIR operation in water has been recently demonstrated [72,73], enabling conformational analysis of molecules at the nanoscale and in their native environment [72]. Recent reviews comparing PTIR with other near-field techniques, such as scattering scanning near field microscopy (s-SNOM) and tip-enhanced Raman spectroscopy (TERS) are available elsewhere [44,74]. Briefly, in contrast with TERS and s-SNOM, which are primarily surface sensitive techniques, PTIR probes samples throughout their thicknesses even in excess of 1 μm [47,75] and it necessitates the probe’s plasmonic enhancement only to measure very thin (< 50 nm) samples.…”

Section: Resultsmentioning

confidence: 99%

Nanoscale chemical imaging of individual chemotherapeutic cytarabine-loaded liposomal nanocarriers

et al. 2018

View full text Add to dashboard Cite

Dosage of chemotherapeutic drugs is a tradeoff between efficacy and side-effects. Liposomes are nanocarriers that increase therapy efficacy and minimize side-effects by delivering otherwise difficult to administer therapeutics with improved efficiency and selectivity. Still, variabilities in liposome preparation require assessing drug encapsulation efficiency at the single liposome level, an information that, for non-fluorescent therapeutic cargos, is inaccessible due to the minute drug load per liposome. Photothermal induced resonance (PTIR) provides nanoscale compositional specificity, up to now, by leveraging an atomic force microscope (AFM) tip contacting the sample to transduce the sample’s photothermal expansion. However, on soft samples (e.g. liposomes) PTIR effectiveness is reduced due to the likelihood of tip-induced sample damage and inefficient AFM transduction. Here, individual liposomes loaded with the chemotherapeutic drug cytarabine are deposited intact from suspension via nES-GEMMA (nano-electrospray gas-phase electrophoretic mobility molecular analysis) collection and characterized at the nanoscale with the chemically-sensitive PTIR method. A new tapping-mode PTIR imaging paradigm based on heterodyne detection is shown to be better adapted to measure soft samples, yielding cytarabine distribution in individual liposomes and enabling classification of empty and drug-loaded liposomes. The measurements highlight PTIR capability to detect ≈ 103 cytarabine molecules (≈ 1.7 zmol) label-free and non-destructively.

show abstract

“…In general, imaging techniques have found increasing interest in methodological development and modern applications. Spectroscopic imaging at a nanoscale is reviewed with regard to technology and recent applications [4]. A classical spectroscopic method is surface enhanced Raman spectroscopy (SERS), which gained extreme interest in environmental analysis, bioanalysis and screening tissue even during operations.…”

Section: Highlights Of Research In Analytical Chemistry -2018mentioning

confidence: 99%