Pore Networks and Polymer Rearrangement on a Drug-Eluting Stent as Revealed by Correlated Confocal Raman and Atomic Force Microscopy

Biggs, Kevin B.; Balss, Karin M.; Maryanoff, Cynthia A.

doi:10.1021/la300808z

Cited by 16 publications

(15 citation statements)

References 19 publications

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“…Taking into account adhesive properties from forcedistance curves between propellant medium and the drug, the formulation can be optimised (Rogueda et al, 2011). Likewise the formation of a pore network during in vitro drug release from a carrier polymer matrix has as well been observed by co-located AFM-Raman (Biggs et al, 2012). Moreover catalytic reactions of metal nanoparticles have also been proofed by this technology (Harvey et al, 2012).…”

Section: Afm Combined With Raman In Biology: From Medicine To New Ementioning

confidence: 97%

“…Spectroscopy studies the interaction between light (of different frequencies) and matter, from which different properties and characteristics of the material can be derived (Harris and Bertolucci, 1989). Concretely Raman spectroscopy has a wide spectrum of applications, due to its non-destructive nature (if correctly applied) and its suitability for combining with other methods such as scanning electron microscopy (SEM) (Cardell and Guerra, 2016;Timmermans et al, 2016), flow cytometry (Biris et al, 2009), or atomic force microscopy (AFM) (Apetri et al, 2006;Biggs et al, 2012;.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Tip in–light on: Advantages, challenges, and applications of combining AFM and Raman microscopy on biological samples

Prats-Mateu

Gierlinger

2016

Microscopy Res & Technique

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Scanning probe microscopies and spectroscopies, especially AFM and Confocal Raman microscopy are powerful tools to characterize biological materials. They are both non‐destructive methods and reveal mechanical and chemical properties on the micro and nano‐scale. In the last years the interest for increasing the lateral resolution of optical and spectral images has driven the development of new technologies that overcome the diffraction limit of light. The combination of AFM and Raman reaches resolutions of about 50–150 nm in near‐field Raman and 1.7–50 nm in tip enhanced Raman spectroscopy (TERS) and both give a molecular information of the sample and the topography of the scanned surface. In this review, the mentioned approaches are introduced, the main advantages and problems for application on biological samples discussed and some examples for successful experiments given. Finally the potential of colocated AFM and Raman measurements is shown on a case study of cellulose‐lignin films: the topography structures revealed by AFM can be related to a certain chemistry by the colocated Raman scan and additionally the mechanical properties be revealed by using the digital pulsed force mode. Microsc. Res. Tech. 80:30–40, 2017. © 2016 Wiley Periodicals, Inc.

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Section: Afm Combined With Raman In Biology: From Medicine To New Ementioning

confidence: 97%

mentioning

confidence: 99%

Tip in–light on: Advantages, challenges, and applications of combining AFM and Raman microscopy on biological samples

Prats-Mateu

Gierlinger

2016

Microscopy Res & Technique

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“…Using correlated confocal Raman and atomic force microscopy, Biggs et al . 5 mapped the chemical composition and topography of the surface and subsurface of the CYPHER stent. They were able to correlate sirolimus elution with structural changes to the surfaces, where the formation of porous regions had taken place.…”

Section: Modelling Drug Release and Distributionmentioning

confidence: 99%

“…They were able to correlate sirolimus elution with structural changes to the surfaces, where the formation of porous regions had taken place. 5 Carlyle et al . 7 employed a vessel simulating loop which incorporated flow analogous to a coronary artery, mimicking pressure, shear stress and velocity, and a biorelevant release medium, to investigate release from an absorbable sirolimus eluting stent coating (AC-SES).…”

Section: Modelling Drug Release and Distributionmentioning

confidence: 99%

Modelling the Impact of Atherosclerosis on Drug Release and Distribution from Coronary Stents

et al. 2015

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Although drug-eluting stents (DES) are now widely used for the treatment of coronary heart disease, there remains considerable scope for the development of enhanced designs which address some of the limitations of existing devices. The drug release profile is a key element governing the overall performance of DES. The use of in vitro, in vivo, ex vivo, in silico and mathematical models has enhanced understanding of the factors which govern drug uptake and distribution from DES. Such work has identified the physical phenomena determining the transport of drug from the stent and through tissue, and has highlighted the importance of stent coatings and drug physical properties to this process. However, there is limited information regarding the precise role that the atherosclerotic lesion has in determining the uptake and distribution of drug. In this review, we start by discussing the various models that have been used in this research area, highlighting the different types of information they can provide. We then go on to describe more recent methods that incorporate the impact of atherosclerotic lesions.

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“…In contrast, confocal Raman microscopy (CRM), as a non‐invasive, chemically selective, and spatially resolved analytical technique overcomes some of the aforementioned obstacles thus gaining increasing interest for advanced characterization of drug delivery systems . This method has already been described as a valuable tool for analysis of a broad range of diverse pharmaceutical samples: solid dispersions, drug‐eluting coatings, polymeric microparticles, and tablets . CRM is utilized for microstructural characterization of drug delivery systems and for better understanding of interactions between different components in formulations.…”

Section: Introductionmentioning

confidence: 99%

Novel insights into controlled drug release from coated pellets by confocal Raman microscopy

Vukosavljevic

Kinder

Siepmann

et al. 2016

J Raman Spectroscopy

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The development of novel therapeutics with improved efficacy implies increasing complexity of drug delivery systems, which in turn require advanced methods for their analytical characterization. Among these systems, pellets represent upcoming carrier systems, which show several advantages like simplified dosing and improved compliance among children and the aged population. However, rational development of such systems is hampered by the lack of non-destructive, chemically selective analytical insight into compound distribution and drug release mechanisms. The aim of this study was to evaluate confocal Raman microscopy (CRM) for investigation of coated drug-loaded pellets based on visualization of compound distribution and elucidation of drug release mechanisms. Three complementary approaches were applied for pellet characterization: analysis of cross sections after bisectioning, non-invasive visualization of the pellet surface, and virtual cross sectioning in x-z direction. As the surface of such pellets is structured, a complementary approach of optical topography and CRM was applied for three-dimensional analysis. Based on the individual Raman peak patterns, the drug and excipients forming the matrix of the pellets and the film coating were successfully visualized with high spatial resolution, verifying homogeneous drug distribution and intact polymer coating of the pellet. Further, analysis of the pellets after certain time intervals during drug release testing revealed pore formation in the polymer coating facilitating drug release and preceding drug depletion in the pellets matrix. CRM represents an upcoming technique for analytical characterization of carrier systems and elucidation of their complex drug release mechanisms, thus supporting rational development of novel therapeutics. Figure 5. Cross sections and virtual cross sections of pellets before (A) and after release testing (B). False colors depict the matrix excipients in blue, film coating in yellow, and the drug in red, respectively.Novel insights into drug release from coated pellets by confocal Raman microscopy

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Pore Networks and Polymer Rearrangement on a Drug-Eluting Stent as Revealed by Correlated Confocal Raman and Atomic Force Microscopy

Cited by 16 publications

References 19 publications

Tip in–light on: Advantages, challenges, and applications of combining AFM and Raman microscopy on biological samples

Tip in–light on: Advantages, challenges, and applications of combining AFM and Raman microscopy on biological samples

Modelling the Impact of Atherosclerosis on Drug Release and Distribution from Coronary Stents

Novel insights into controlled drug release from coated pellets by confocal Raman microscopy

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