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► Low-fouling carboxymethyl dextran surfaces bearing RGD and RGE were fabricated. ► PANC-1 cells clustered to form islet-like aggregates for each surface. ► Islet-like aggregates ...expressed insulin and glucagon after 14days. ► Islet-like aggregates exposed to RGD surfaces were the smallest. ► Islet-like aggregates exposed to RGD surfaces had the highest insulin secretion.
Substrates bearing low-fouling carboxymethyl dextran (CMD) upon which RGD is covalently grafted were validated to study PANC-1 cell differentiation in serum-free medium. When exposed to RGD-CMD, cells lightly adhered to the surface and formed islet-like aggregates (ILAs) in contact with the surface. PANC-1 were non-adherent on RGE-CMD, CMD, and tissue culture polystyrene surfaces and aggregated in suspension forming ILAs. RGD-CMD resulted in smaller ILAs. Ki67 and CK-19 expression decreased after 3, 7, and 14days. E-cadherin expression did not change from 3 to 7days, but decreased after 14days. For each marker, there was no difference in the expression between the surfaces. After 14days, ILAs weakly expressed insulin and glucagon and the expression level was independent of the surfaces. No convincing level of insulin or glucagon was detected by immunostaining at 3 and 7days. A higher level of insulin release was detected in the media after 14days for cells grown on RGD-CMD. After 14days, there were three-fold more cells on RGD-CMD surfaces compared to cell numbers found in other culture conditions. α5 integrin expression was rampant throughout ILAs for all four surfaces. αVβ3 integrin expression was only noticeable for ILAs cultured on RGD-CMD surfaces.
This study reveals that it is possible to obtain a specific cell response towards low-fouling carboxymethyl dextran (CMD) surfaces bearing the RGD adhesive peptide in fibrin. To avoid cell ...sedimentation on surfaces observed in traditional cell culture systems, CMD surfaces bearing RGD were vertically embedded in fibrin containing human umbilical vein endothelial cells (HUVEC) and their effect over cells was investigated. Compared to the CMD surfaces and to CMD layers bearing the negative control RGE, RGD coatings promoted cell adhesion, induced focal contact formation indicated by co-localization of vinculin and actin fibers, and presented a significant effect over HUVEC net growth during the first 24
h of the culture, as revealed by Ki67 staining and cell counting. The intracellular localization of caveolin-1 combined with the expression of beta 1 integrins was investigated and the orientation of HUVEC towards and on the RGD surfaces was studied. When compared to the negative controls, HUVEC responded to the RGD surface in fibrin resulting in acceleration of morphological changes. RGD surfaces supported fibrin degradation by HUVEC as revealed by fluorescent fibrin experiments as well as multi-cellular structure formation, vacuolation and lumen formation.
Hydrophobic and hydrophilic particles of iron oxide (magnetite/maghemite) with diameter of 6–10 nm were prepared by hydrothermal hydrolysis of iron oleate in water/pentanol/oleic acid system at ...180 °C. The hydrophobic/hydrophilic nature of resulting particles was controlled by the presence of sodium oleate and by manipulating the ionic strength (with NaCl). The final particle size was controlled by additional organic solvent (octanol or toluene) and by seed growth. Hydrophilic particles (6 nm) were further modified by carboxymethyl-dextran in water to obtain stable and well-dispersed superparamagnetic nanoparticles suitable for biomedical application. The prepared particles were characterized by transmission electron microscopy, thermogravimetry, Fourier-transform infrared spectroscopy, magnetic measurements, Mössbauer spectroscopy, dynamic light scattering, and zeta-potential measurement.
Clinically available taxanes, such as paclitaxel and docetaxel, represent one of the most promising classes of anticancer agents, despite their toxicity. To improve their pharmacological profiles, ...AZ10992 was synthesized based on the concept that a rational design of a polymer–drug conjugate would increase the efficacy of the parent drug. This prodrug is a paclitaxel–carboxymethyl dextran conjugate (molecular weight 150,000 g/mol) via a gly–gly–phe–gly linker. The
in vivo antitumor study using AZ10992 against colon26 carcinoma cells, resistant to paclitaxel, supported this concept. Additionally, the comparative efficacy studies of AZ10992 and paclitaxel using a panel of human tumor xenografts in nude mice showed the advantages of drug–polymer conjugation. The maximum tolerated dose of AZ10992 was more than twice as high as the MTD of paclitaxel. A repeated intravenous administration of AZ10992 at 30 mg/kg/day (five injections for 4-days) showed complete regression of MX-1 mammary carcinoma xenografts. Also, HT-29 colorectal tumor xenografts, which are highly refractory to paclitaxel, showed complete regression after AZ10992 administered at 30 mg/kg/day (seven injections for 4-days). Pharmacokinetic studies showed that there were significant increases in the amount and the exposure time of total paclitaxel in the tumors after intravenous administration of AZ10992, which explains the enhanced efficacy of AZ10992.
This study reports the fouling of carboxymethyl dextran (CMD) layers in cell culture medium, fibronectin, and serum solutions. CMD layers were covalently immobilized onto amine groups available ...either on an
n-heptylamine plasma polymer (HApp) layer or onto a polyethylenimine (PEI) coating grafted to an acetaldehyde plasma polymer (AApp) layer. The successful immobilization of the graft layers was demonstrated by X-ray photoelectron spectroscopy (XPS). Primary amines on HApp and AApp
+
PEI surfaces were quantified using a colorimetric assay. Quartz crystal microbalance (QCM) was used to investigate in real-time the fouling of the graft layers upon incubation in cell culture medium (RPMI), fibronectin, and foetal bovine serum (FBS) solutions. HApp, AApp and AApp
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PEI layers exhibited large fouling in fibronectin and FBS solutions, while fouling in RPMI cell culture medium was not significant. Protein repellent properties of CMD layers in FBS and fibronectin have been demonstrated compared to the other tested surfaces. QCM has shown that both CMD layers were fouled to a small extent in RPMI medium.
Surface plasmon resonance (SPR) based biosensor technology has been widely used in life science research for many applications. While the advantages of speed, ruggedness, versatility, sensitivity and ...reproducibility are often quoted, many researchers have experienced severe problem of non-specific binding (NSB) to chip surfaces when performing analysis of biological samples such as bovine serum. Using the direct measurement of the bovine protein leptin, present in bovine serum samples as a model, a unique buffering system has been developed and optimised which was able to significantly reduce the non-specific interactions of bovine serum components with the carboxymethyl dextran chip (CM5) surface on a Biacore SPR system. The developed NSB buffering system comprised of HBS-EP buffer, containing 0.5
M NaCl, 0.005% CM-dextran, pH 9.0. An average NSB reduction (
n
=
20) of 85.9% and 87.3% was found on an unmodified CM5 surface and a CM5 with bovine leptin immobilised on the chip surface, respectively. A reduction in NSB of up to 94% was observed on both surfaces. The concentration of the constitutive components and pH of the buffer were crucial in achieving this outcome.
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► Fibronectin (FN) exposed to low-fouling carboxymethyl dextran (CMD) surfaces. ► Only FN solutions with low salt concentration resulted in FN immobilization to CMD. ► Insulinoma ...(INS-1) cells were seeded to FN-CMD and FN-Glass surfaces. ► INS-1 cell growth uninfluenced by solution composition during FN immobilization. ► FN solution composition impacts INS-1 insulin secretion in response to glucose.
It is shown that solution composition during immobilization plays a critical role in the properties of fibronectin (FN) surfaces and their bioactivity towards insulinoma (INS-1) cell function. X-ray photoelectron spectroscopy revealed FN grafting onto low-fouling carboxymethyl-dextran (CMD) surfaces was successful with solutions composed of 10μM CaCl2, 10μM MgCl2, 10μM MnCl2, and 10μM and 1mM NaCl, but unsuccessful with those made of 150mM NaCl or 1× PBS. Circular dichroism and photon correlation spectroscopy revealed that regardless of solution composition, no measurable differences in free FN conformation prevail. AFM imaging of FN-CMD revealed, while there are no quantitative differences in surface roughness, there are some subtle qualitative differences in topography. FN surface immobilization scheme does not influence INS-1 cell growth after 3 and 7 days regardless of the underlying substrate or solution composition. INS-1 cell insulin secretion in response to glucose is affected by the substrate and solution composition during FN immobilization.
Magnetite nanoparticles, which were synthesized by using diethylene glycol (DEG) as both solvent and reductant, displayed excellent hydrophilicity and water dispersibility. The influences of the ...amount of carboxymethyl-dextran sodium salt and NaOH on nanoparticles dispersibility were evaluated in terms of zeta potentials, concentration variation under centrifugal field, Fourier transform infrared, and X-ray photoelectron spectra, respectively. The results showed that the water dispersibility is not related to the amount of carboxymethyl-dextran, but depends on that of NaOH. Further evaluation revealed that DEG was partially oxidized with the assistance of NaOH, and thanks to the resultant carbonyl groups, the flexible oxidized DEG chains were anchored on the nanoparticles surface, which provides sufficient protection and high water-dispersibility of the as-prepared magnetite nanoparticles. Furthermore, we suggest that the binding between carbonyl groups and nanoparticles is related to the electron-withdrawing effect. The current study may provide more selectiveness of modifying molecules for magnetite nanoparticles.
