Interaction of water with different cellulose ethers: a Raman spectroscopy and environmental scanning electron microscopy study

Fechner, Petra M.; Wartewig, S.; Kiesow, Andreas; Heilmann, Andreas; Kleinebudde, Peter; Neubert, R.

doi:10.1211/0022357056109

Cited by 27 publications

(21 citation statements)

References 36 publications

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“…Secondly, the incorporation of drugs within hydrogels is frequently performed by immersion of the dried hydrogel into a solution of the required drug, the mass of drug absorbed being directly proportional to the swelling properties of the hydrogel. Typically the swelling of hydrogels in aqueous solutions is controlled by the compatibility of the polymer with the selected aqueous fluid and by the degree of crosslinking in the hydrogel network (Rosiak & Yoshii 1999;Tritt-Goc et al 2003;Fechner et al 2005). Therefore the effect of crosslinker concentration on the swelling ratio of the hydrogels under examination may be primarily accredited to the increased degree of crosslinking (Davis & Huglin 1989;Corkhill et al 1990).…”

Section: Discussionmentioning

confidence: 99%

Characterization of crosslinking effects on the physicochemical and drug diffusional properties of cationic hydrogels designed as bioactive urological biomaterials

Jones

Andrews

Gorman

2005

Journal of Pharmacy and Pharmacology

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This study examined the effects of concentration and type of crosslinker (tetraethyleneglycol diacrylate, TEGDA; diethyleneglycol dimethacrylate, DEGDMA; and polyethyleneglycol dimethacrylate, PEGDMA) on the mechanical and drug diffusional properties of hydrogels that had been selected as candidate coatings for bioactive medical devices. Hydrogels (dimethylaminoethylmethacrylate-co-vinylpyrrolidone; 1:1) were prepared by free radical polymerization and characterized using tensile analysis, dynamic contact angle analysis and analysis of swelling at pH 6.0. The release of fusidic acid and chlorhexidine was evaluated using buffered medium at pH 6.0 and, in addition, using dissolution medium that had been buffered to pH 9 in the presence and absence of elevated concentrations of calcium, representative of urinary encrustation. Crosslinker concentration, but not type, affected the advancing and receding contact angles. Conversely, both crosslinker type and concentration affected the mechanical and swelling properties of the hydrogels. Maximum swelling and elongation at break were associated with the PEGDMA-crosslinked hydrogels whereas TEGDA-crosslinked hydrogels exhibited the maximum ultimate tensile strength and Young's modulus. Drug release from all systems occurred by diffusion. The mass of chlorhexidine and fusidic acid released was dependent on crosslinker type and concentration, with hydrogels crosslinked with PEGDMA offering the greatest mass of drug released at each sampling period. The mass of fusidic acid but not chlorhexidine released at pH 9.0 in a calcium augmented medium was lower than that released in the same medium devoid of elevated calcium, due to the formation of the poorly soluble calcium salt. In conclusion, this study has uniquely examined the effects of crosslinker type and concentration on physicochemical and drug release properties essential to the clinical and non-clinical performance of bioactive hydrogels for medical device application.

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Section: Discussionmentioning

confidence: 99%

Characterization of crosslinking effects on the physicochemical and drug diffusional properties of cationic hydrogels designed as bioactive urological biomaterials

Jones

Andrews

Gorman

2005

Journal of Pharmacy and Pharmacology

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“…The objective of this study was to characterise various native and modified starches using Raman spectroscopy and environmental scanning electron microscopy (ESEM). The combination of these methods allows molecular and morphological properties to be investigated as shown in previous studies with cellulose and its derivatives [27,28]. Investigations were carried out on raw starches, gels, and films.…”

Section: Introductionmentioning

confidence: 99%

Influence of Water on Molecular and Morphological Structure of Various Starches and Starch Derivatives

et al. 2005

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In this study the influence of water on untreated, pregelatinised, and chemical modified starches was investigated. Because of their different botanical source, the starch products contain various quantities of amylose and amylopectin. The water vapour absorption capacity of the starches was studied by sorption/desorption and thermogravimetrical measurements. Higher absorption capacities were found for potato starch and for starches containing carboxymethyl and hydroxyethyl groups. Characteristic molecular differences found by Raman spectroscopy were evaluated for untreated and modified starches. To this end, the starch raw materials were classified into groups with similar pretreatments and properties based on cluster analysis. Additionally, the gelatinisation of starch-water mixtures (gels, powders, and films) was continuously studied using temperature-dependent Raman spectroscopy. In comparison with powder spectra, the Raman spectra of the starch films showed shifts in band positions in the range of the CH deformation and CH stretching modes. With the exceptions of high-amylose maize starch and carboxymethylated starch, all starches form films. Starch films differ in their surface structures, water contact angles, and rates of water drop absorption, which might be caused by the different retrogradation properties. The swelling and shrinking behaviour of starch films was investigated at the morphological level by in situ environmental scanning electron microscopy (ESEM) experiments and evaluated by grey value analysis. Films of untreated starch show stronger swelling and shrinking than films of pregelatinised products.

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“…No distinctive spectral patterns that could indicate the direct interaction of the HPC with silver nanoparticle surfaces are observed. Weak bands assigned to CH stretching vibrations at 2,885 and 2,943 cm −1 and CH deformations at 1,458 cm −1 of the HPC polymer are seen . The broad band at approximately 1,640 cm −1 characteristic of water molecules vibrations is also observed.…”

Section: Resultsmentioning

confidence: 77%

“…In the spectrum of AgHPC1_365 exposed to light for 24 hr, carbon background broad bands at approximately 1,380 and 1,600 cm −1 are visible (due to the laser irradiation used in the Raman measurements). Weak bands of HPC at 818 and 931 cm −1 , assigned to COC and CC stretching modes, are also observed. These bands suggest a weak interaction of silver with HPC in the proximity of the ether group.…”

Section: Resultsmentioning

confidence: 85%

Characterization of HPC‐based photoreduced SERS substrates and detection of different organic dyes

Retko

Ropret

Korošec

et al. 2018

J Raman Spectroscopy

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Silver nanoparticles were fabricated in situ in the hydroxypropyl cellulose (HPC) matrix by irradiation at different wavelengths (365 and 254 nm) following the principles of green chemistry. HPC is involved in the silver reduction process and in the stabilization as well. Characteristics of the dispersions depend on the weight ratio between silver ions and HPC, irradiation time, and energy of the incident irradiation. Interaction at higher energies leads to higher degradation of the HPC matrix, resulting also in lower pH values of the dispersion. The latter is even more pronounced when using lower initial concentrations of silver nitrate. Different formulations were tested as surface‐enhanced Raman scattering (SERS) substrates with alizarin solutions and several other probes. Different spectral responses are related to different surface availability and/or to differences in microenvironment or macroenvironment of the nanoparticles. Substrates irradiated at lower energies show superior properties in terms of stability, whereas the substrates with a lower concentration of silver ions and irradiated with higher energies are more suitable for the detection of compounds with acidic properties (such as carminic acid and lac dye) due to lower electrostatic repulsion between the compounds and nanoparticles.

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Interaction of water with different cellulose ethers: a Raman spectroscopy and environmental scanning electron microscopy study

Cited by 27 publications

References 36 publications

Characterization of crosslinking effects on the physicochemical and drug diffusional properties of cationic hydrogels designed as bioactive urological biomaterials

Characterization of crosslinking effects on the physicochemical and drug diffusional properties of cationic hydrogels designed as bioactive urological biomaterials

Influence of Water on Molecular and Morphological Structure of Various Starches and Starch Derivatives

Characterization of HPC‐based photoreduced SERS substrates and detection of different organic dyes

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