Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0267964 (PAA)
 2,561 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Cellular patterning on biomaterial surfaces is important in fundamental studies of cell-cell and cell-substrate interactions, and in biomedical applications such as tissue engineering, cell-based biosensors, and diagnostic devices. In this study, we combined the layer-by-layer polyelectrolyte multilayer deposition and photolithographic technique to create an easy and versatile technique for cell patterning. Poly(acrylic acid) (PAA) conjugated with 4-azidoaniline was interwoven in PAA/polyacrylamide (PAM) multilayer films. After UV irradiation through a photo mask, the UV-exposed areas were crosslinked and the unexposed areas were rinsed away by alkaline water, resulting in micropatterns. Cell patterns were formed when the cell adhesion was limited to the base substrate, but not on the multilayer films. The stability of cell patterns could be modulated by simply modification of the surface chemistry of base substrate and PEM films with conjugation of bioactive macromolecules. This technique can be also applied to other PEM systems with proper rinsing protocol, and many types of substrates. Cell co-culture systems can be also achieved by this technique.
 ...
PMID:Spatial control of cellular adhesion using photo-crosslinked micropatterned polyelectrolyte multilayer films. 1915 Jul 38

Considering restrictive diabetes treatments, new insulin administration strategies constitute a huge medical challenge. This study aimed at developing a new support for insulin reservoirs, using polyelectrolyte multilayer films (PEM films), and thus studying this hormone release in a progressive manner. At first, insulin was loaded in (PDADMAC-PAA)n films, by immerging them for various periods of time (2, 14 and 24 h) in a solution containing this protein. Confocal laser scanning microscopy (CLSM) revealed that insulin-FITC could diffuse inside the film with a bigger concentration in the upper part of the film (after 2 and 14 h in contact with the polypeptide solution), and then in the whole film (after 24 h) from a solution at pH=4.3 (below insulin's isolelectric point). Environmental scanning electron microscopy (ESEM) and CLSM showed that the film swells upon insulin loading. We finally investigated the insulin release by ATR-FTIR spectroscopy. It revealed that a loaded (PDADMAC-PAA)15 film, immerged in distilled water, showed no measurable insulin release. In contrast, a slow unloading was observed in the presence of a NaCl 0.15 M solution (salinity close to physiological serum). This study could open the route for a new way of insulin delivery.
 ...
PMID:Polyelectrolyte multilayer films: A sponge for insulin? 2093 Mar 31

In-situ ATR-FTIR spectroscopy and line shape analysis of the diagnostic spectral region was used to quantify the bound amount and release of the antibiotic streptomycin (STRP) at polyelectrolyte (PEL) multilayers (PEM) of poly(ethyleneimine) (PEI) and poly(acrylic acid) (PAA) or PEI and sodium alginate (ALG). Unlike common concepts based on the drug enrichment of the release medium, this analytical concept allowed to measure quantitatively the drug depletion in the delivery matrix. The measured kinetic in situ ATR-FTIR data were analysed by a modified Korsmeyer-Peppas equation based on two characteristic release parameters k and n. As main experimental parameters the number of PEL layers (adsorption steps) z and the STRP/PEL ratio were varied. For z=8 the STRP/PEL ratio showed the most significant influence on release kinetics, whereby for STRP/PEL=1:25 slowest (n=0.77) and lowest (k=21.4%) and for STRP/PEL=1:5 most rapid (n=0.30) and highest (k=58.6%) drug releases were found. PEM-PEI/ALG-8 (STRP/PEL=1:5) revealed slower release rates (n=0.58) and lower released STRP amounts (k=17.1%) compared to PEI/PAA. UV-VIS data on time dependent STRP enrichment of the release medium showed a similar trend compared to respective ATR-FTIR data on STRP depletion in PEM. Released amounts of around 1-2mg from the herein introduced PEM films could be determined. The introduced analytical concept will be used as screening tool for other drugs, drug eluting films and bone substituting materials.
 ...
PMID:In situ-ATR-FTIR analysis on the uptake and release of streptomycin from polyelectrolyte complex layers. 2335 80

Controlling the uptake of specific ions in polyelectrolyte multilayers is of interest for various fields of application. Here, we quantify the amount of cation of an ionic liquid, namely 1,3-bis(cyanomethyl)imidazolium chloride, incorporated into polyelectrolyte multilayers upon contact with an ionic liquid solution. The ion partition equilibrium is determined depending on concentration in solution, employing attenuated total reflection infrared spectroscopy. Generating an excess charge in multilayers by post-preparative manipulation of their charge balance, one can control the incorporated amount. Three multilayer systems are assembled for this purpose, i.e., PSS/PDADMAC, PSS/PAH and PAA/PDADMAC, employing poly(styrene sulfonate) (PSS), poly(diallyldimethylammonium chloride) (PDADMAC), poly(allylamine hydrochloride) (PAH) and poly(acrylic acid) (PAA). The charge balance of the latter two films is manipulated by an external pH stimulus generating an excess positive or negative internal charge, respectively. The concentration of cations in PEM amounts to 30% to 100% of the bulk concentration and scales as PAA/PDADMAC > PSS/PDADMAC > PSS/PAH. Thus, post-preparative pH treatment may be a future tool to create ion-conductive polymer gel films with a desired concentration of small cations.
 ...
PMID:Quantifying and controlling the cation uptake upon hydrated ionic liquid-induced swelling of polyelectrolyte multilayers. 2818 20

The deposition and nanostructure of polyelectrolyte (PEL) multilayers (PEMs) of branched poly(ethyleneimine)/poly(acrylic acid) (PEI/PAA) onto silicon substrates was studied in terms of the dependence of pH and the PEL concentration (cPEL) in the individual adsorption steps z. Both a commercial automatic dipping device and a homebuilt automatic stream coating device (flow cell) were used. Gravimetry, SFM, transmission (TRANS) and in situ attenuated total reflection (ATR) FTIR spectroscopy were used for the quantitative determination of the adsorbed amount, thickness, chemical composition and morphology of deposited PEMs, respectively. Firstly, the combination of pH = 10 for PEI and pH = 4 for PAA, where both PEL were predominantly in the neutral state, resulted in an extraordinarily high PEM deposition, while pH combinations, where one PEL component was charged, resulted in a significantly lower PEM deposition. This was attributed to both PEL conformation effects and acid/base interactions between basic PEI and acidic PAA. Secondly, for that pH combination an exponential relationship between PEM thickness and adsorption step z was found. Thirdly, based on the results of three independent methods, the course of the deposited amount of a PEM-10 (z = 10) versus cPEL in the range 0.001 to 0.015 M at pH = 10/4 was non-monotonous showing a pronounced maximum at cPEL = 0.005 M. Analogously, for cPEL = 0.005 M a maximum of roughness and structure size was found. Fourthly, related to that finding, in situ ATR-FTIR measurements gave evidence for the release of outermost located PEI upon PAA immersion (even step) and of outermost PAA upon PEI immersion (odd step) under formation of PEL complexes in solution. These studies help us to prepare PEL-based films with a defined thickness and morphology for interaction with biofluids in the biomedical and food fields.
 ...
PMID:The Anomalous Influence of Polyelectrolyte Concentration on the Deposition and Nanostructure of Poly(ethyleneimine)/Poly(acrylic acid) Multilayers. 3117 7