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The present study aims to develop thermosensitive membranes with an intelligent mechanism of adhesion/release and potent antimicrobial action for the treatment of wounds. The membranes were prepared by electrosynthesis of the thermosensitive hydrogel poly (N-isopropylacrylamide) (PNIPAm) in the presence of chitosan (CHI). The material obtained is constituted by a semi-interpenetrating polymer network (sIPN) of CHI and PNIPAm. The chitosan is a natural biopolymer with activity bactericidal, anti-inflammatory and healing action. The commercial chitosan used was previously characterized in terms of its average molar mass (0.9312 * 105 g mol-1) by viscosimetric method and degree of deacetylation (86.23%), through conductometric titration. The PNIPAm hydrogel was incorporated to CHI polymer chain by electrochemical method using cyclic voltammetry technique. The sIPN CHI-PNIPAm membrane obtained was characterized by Fourier Transform Infrared Spectroscopy using the Attenuated Total Reflectance (FTIR-ATR), differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). FTIR-ATR spectra confirmed the polymerization of PNIPAm in the presence of CHI. TGA curve showed that sIPN membrane obtained has a composition of 33% chitosan and 55% PNIPAm. DSC thermal analysis showed a lower Tg of sIPN CHI-PNIPAm membrane compared to Tg of PNIPAm hydrogel. The phase transition temperature (LCST) of the sIPN CHI-PNIPAm membrane was determined by Ultaviolet-visible spectroscopy (UV-vis) the value found was 32 ° C., O presente trabalho visa desenvolver membranas termossensíveis com um mecanismo inteligente de adesão/liberação e potente ação antimicrobiana para o tratamento de feridas. As membranas foram preparadas através da eletrossíntese do hidrogel termossensível poli(N-isopropilacrilamida) (PNIPAm) na presença da quitosana (QUI). O material final constitui uma rede polimérica semi-interpenetrante (sIPN) de QUI e PNIPAm. A quitosana é um biopolímero natural que possui ação bactericida, anti-inflamatória e cicatrizante. A quitosana comercial utilizada foi previamente caracterizada em termos de sua massa molar média (0,9312 * 105 g mol-1) por método viscosimétrico e grau de desacetilação (86,23%), através de titulação condutimétrica. O hidrogel PNIPAm foi incorporado à cadeia polimérica da QUI por via eletroquímica através da técnica de voltametria cíclica. A membrana sIPN QUI-PNIPAm obtida foi caracterizada por Espectroscopia no infravermelho por transformada de Fourier usando o modulo de Refletância Total Atenuada (FTIR-ATR), calorimetria exploratória diferencial (DSC) e termogravimétrica (TG). O espectro FTIR-ATR confirmou a polimerização do PNIPAm na presença da QUI. A curva TG mostrou que a membrana sIPN obtida apresenta uma composição de 33% de quitosana e 55% de PNIPAm. A análise térmica por DSC mostrou que a Tg da membrana sIPN QUI-PNIPAm é mais baixa que a Tg do hidrogel PNIPAm. A temperatura de transição de fase (LCST) da membrana sIPN QUI-PNIPAm foi determinada por espectroscopia na região do ultravioleta visível (UV-vis), onde valor encontrado foi de 32ºC., El presente trabajo busca desarrollar membranas termosensibles con un mecanismo inteligente de adhesión / liberación y potente acción antimicrobiana para el tratamiento de las heridas. Las membranas fueron preparadas a través de la electrossíntesis del hidrogel termossensible poli (N-isopropilacrilamida) (PNIPAm) en presencia de la quitosana (QUI). El material final constituye una red polimérica semi-interpenetrante (sIPN) de QUI y PNIPAm. La quitosana es un biopolímero natural que tiene acción bactericida, anti-inflamatoria y cicatrizante. La quitosana comercial utilizada fue previamente caracterizada en términos de su masa molar media (0,9312 * 105 g mol-1) por método viscosimétrico y grado de desacetilación (86,23%), a través de titulación conductimétrica. El hidrogel PNIPAm fue incorporado a la cadena polimérica de la QUI por vía electroquímica a través de la técnica de vueltametría cíclica. La membrana sIPN QUI-PNIPAm obtenida fue caracterizada por Espectroscopia en el infrarrojo por transformada de Fourier usando el modulo de Reflección Total Atenuada (FTIR-ATR), calorimetría exploratoria diferencial (DSC) y termogravimétrica (TG). El espectro FTIR-ATR confirmó la polimerización del PNIPAm en presencia de la QUI. La curva TG mostró que la membrana sIPN obtenida presenta una composición de 33% de quitosana y 55% de PNIPAm. El análisis térmico por DSC mostró que la Tg de la membrana sIPN QUI-PNIPAm es más baja que la Tg del hidrogel PNIPAm. La temperatura de transición de fase (LCST) de la membrana sIPN QUI-PNIPAm fue determinada por espectroscopia en la región del ultravioleta visible (UV-vis), donde el valor encontrado fue de 32ºC.

Use of biomaterials in autoimmunity research is widely explored, as an adjuvant to induce antigen specific immune responses, for facilitating induction of experimental models to study disease pathogenesis and for designing novel therapeutic targets. Similarly, polymeric biomaterials are explored as a delivery vehicle for sustained and specific release of auto-antigens/drugs to treat autoimmune disorders. Although considered as biocompatible, implantation/injection of polymers like silica and metallic implants are associated with development of chronic inflammation and autoimmunity. Despite these compatibility concerns, biomaterials are still considered as favorable materials for several applications in the autoimmunity field.

Understanding the nature of adjuvants and the immune priming events in autoimmune diseases, such as rheumatoid arthritis, is a key challenge to identify their aetiology. Adjuvants are, however, complex structures with inflammatory and immune priming properties. Synthetic polymers provide a possibility to separate these functions and allow studies of the priming mechanisms in vivo. A well-balanced polymer, poly-N-isopropyl acrylamide (PNiPAAm) mixed with collagen type II (CII) induced relatively stronger autoimmunity and arthritis compared with more hydrophilic (polyacrylamide) or hydrophobic (poly-N-isopropylacrylamide-co-poly-N-tertbutylacrylamide and poly-N-tertbutylacrylamide) polymers. Clearly, all the synthesized polymers except the more hydrophobic poly-N-tertbutylacrylamide induced arthritis, especially in Ncf1-deficient mice, which are deficient in reactive oxygen species (ROS) production. We identified macrophages as the major infiltrating cells present at PNiPAAm-CII injection sites and demonstrate that ROS produced by the macrophages attenuated the immune response and the development of arthritis. Our results reveal that thermo-responsive polymers with high immune priming capacity could trigger an autoimmune response to CII and the subsequent arthritis development, in particular in the absence of NOX2 derived ROS. Importantly, ROS from macrophages protected against the autoimmune priming, demonstrating a critical regulatory role of macrophages in immune priming events.

Understanding the nature of adjuvants and the immune priming events in autoimmune diseases, such as rheumatoid arthritis, is a key challenge to identify their aetiology. Adjuvants are, however, complex structures with inflammatory and immune priming properties. Synthetic polymers provide a possibility to separate these functions and allow studies of the priming mechanisms in vivo. A well-balanced polymer, poly-N-isopropyl acrylamide (PNiPAAm) mixed with collagen type II (CII) induced relatively stronger autoimmunity and arthritis compared with more hydrophilic (polyacrylamide) or hydrophobic (poly-N-isopropylacrylamide-co-poly-N-tertbutylacrylamide and poly-N-tertbutylacrylamide) polymers. Clearly, all the synthesized polymers except the more hydrophobic poly-N-tertbutylacrylamide induced arthritis, especially in Ncf1-deficient mice, which are deficient in reactive oxygen species (ROS) production. We identified macrophages as the major infiltrating cells present at PNiPAAm-CII injection sites and demonstrate that ROS produced by the macrophages attenuated the immune response and the development of arthritis. Our results reveal that thermo-responsive polymers with high immune priming capacity could trigger an autoimmune response to CII and the subsequent arthritis development, in particular in the absence of NOX2 derived ROS. Importantly, ROS from macrophages protected against the autoimmune priming, demonstrating a critical regulatory role of macrophages in immune priming events.

Understanding the nature of adjuvants and the immune priming events in autoimmune diseases, such as rheumatoid arthritis, is a key challenge to identify their aetiology. Adjuvants are, however, complex structures with inflammatory and immune priming properties. Synthetic polymers provide a possibility to separate these functions and allow studies of the priming mechanisms in vivo. A well-balanced polymer, poly-N-isopropyl acrylamide (PNiPAAm) mixed with collagen type II (CII) induced relatively stronger autoimmunity and arthritis compared with more hydrophilic (polyacrylamide) or hydrophobic (poly-N-isopropylacrylamide-co-poly-N-tertbutylacrylamide and poly-N-tertbutylacrylamide) polymers. Clearly, all the synthesized polymers except the more hydrophobic poly-N-tertbutylacrylamide induced arthritis, especially in Ncf1-deficient mice, which are deficient in reactive oxygen species (ROS) production. We identified macrophages as the major infiltrating cells present at PNiPAAm-CII injection sites and demonstrate that ROS produced by the macrophages attenuated the immune response and the development of arthritis. Our results reveal that thermo-responsive polymers with high immune priming capacity could trigger an autoimmune response to CII and the subsequent arthritis development, in particular in the absence of NOX2 derived ROS. Importantly, ROS from macrophages protected against the autoimmune priming, demonstrating a critical regulatory role of macrophages in immune priming events.

Understanding the nature of adjuvants and the immune priming events in autoimmune diseases, such as rheumatoid arthritis, is a key challenge to identify their aetiology. Adjuvants are, however, complex structures with inflammatory and immune priming properties. Synthetic polymers provide a possibility to separate these functions and allow studies of the priming mechanisms in vivo. A well-balanced polymer, poly-N-isopropyl acrylamide (PNiPAAm) mixed with collagen type II (CII) induced relatively stronger autoimmunity and arthritis compared with more hydrophilic (polyacrylamide) or hydrophobic (poly-N-isopropylacrylamide-co-poly-N-tertbutylacrylamide and poly-N-tertbutylacrylamide) polymers. Clearly, all the synthesized polymers except the more hydrophobic poly-N-tertbutylacrylamide induced arthritis, especially in Ncf1-deficient mice, which are deficient in reactive oxygen species (ROS) production. We identified macrophages as the major infiltrating cells present at PNiPAAm-CII injection sites and demonstrate that ROS produced by the macrophages attenuated the immune response and the development of arthritis. Our results reveal that thermo-responsive polymers with high immune priming capacity could trigger an autoimmune response to CII and the subsequent arthritis development, in particular in the absence of NOX2 derived ROS. Importantly, ROS from macrophages protected against the autoimmune priming, demonstrating a critical regulatory role of macrophages in immune priming events.

Understanding the nature of adjuvants and the immune priming events in autoimmune diseases, such as rheumatoid arthritis, is a key challenge to identify their aetiology. Adjuvants are, however, complex structures with inflammatory and immune priming properties. Synthetic polymers provide a possibility to separate these functions and allow studies of the priming mechanisms in vivo. A well-balanced polymer, poly-N-isopropyl acrylamide (PNiPAAm) mixed with collagen type II (CII) induced relatively stronger autoimmunity and arthritis compared with more hydrophilic (polyacrylamide) or hydrophobic (poly-N-isopropylacrylamide-co-poly-N-tertbutylacrylamide and poly-N-tertbutylacrylamide) polymers. Clearly, all the synthesized polymers except the more hydrophobic poly-N-tertbutylacrylamide induced arthritis, especially in Ncf1-deficient mice, which are deficient in reactive oxygen species (ROS) production. We identified macrophages as the major infiltrating cells present at PNiPAAm-CII injection sites and demonstrate that ROS produced by the macrophages attenuated the immune response and the development of arthritis. Our results reveal that thermo-responsive polymers with high immune priming capacity could trigger an autoimmune response to CII and the subsequent arthritis development, in particular in the absence of NOX2 derived ROS. Importantly, ROS from macrophages protected against the autoimmune priming, demonstrating a critical regulatory role of macrophages in immune priming events.

Understanding the nature of adjuvants and the immune priming events in autoimmune diseases, such as rheumatoid arthritis, is a key challenge to identify their aetiology. Adjuvants are, however, complex structures with inflammatory and immune priming properties. Synthetic polymers provide a possibility to separate these functions and allow studies of the priming mechanisms in vivo. A well-balanced polymer, poly-N-isopropyl acrylamide (PNiPAAm) mixed with collagen type II (CII) induced relatively stronger autoimmunity and arthritis compared with more hydrophilic (polyacrylamide) or hydrophobic (poly-N-isopropylacrylamide-co-poly-N-tertbutylacrylamide and poly-N-tertbutylacrylamide) polymers. Clearly, all the synthesized polymers except the more hydrophobic poly-N-tertbutylacrylamide induced arthritis, especially in Ncf1-deficient mice, which are deficient in reactive oxygen species (ROS) production. We identified macrophages as the major infiltrating cells present at PNiPAAm-CII injection sites and demonstrate that ROS produced by the macrophages attenuated the immune response and the development of arthritis. Our results reveal that thermo-responsive polymers with high immune priming capacity could trigger an autoimmune response to CII and the subsequent arthritis development, in particular in the absence of NOX2 derived ROS. Importantly, ROS from macrophages protected against the autoimmune priming, demonstrating a critical regulatory role of macrophages in immune priming events. © 2016 John Wiley & Sons Ltd., Funding text: We thank Carlos and Kristina Palestro for taking care of the animals. The following foundations provided financial support: Swedish Rheumatism Association, King Gustaf V's 80-years, the Swedish Foundation for Strategic Research, the Swedish Science Research Council including the VR-Link (2008-6007) and VR-project grant (2009-2338). AK acknowledges a DBT TATA Innovation Fellowship.

Well-defined cellulose-graft-polyacrylamide copolymers were synthesized in a grafting-from approach by reversible addition-fragmentation chain transfer polymerization (RAFT). A chlorine moiety (degree of substitution DS(Cl) ≈ 1.0) was introduced into the cellulose using 1-butyl-3-methylimidazolium chloride (BMIMCl) as solvent before being substituted by a trithiocarbonate moiety resulting in cellulose macro-chain transfer agents (cellulose-CTA) with DS(RAFT) of 0.26 and 0.41. Poly(N,N-diethylacrylamide) (PDEAAm) and poly(N-isopropylacrylamide) (PNIPAM) were subsequently grafted from these cellulose-CTAs and the polymerization kinetics, the molecular weight characteristics and the product composition were studied by nuclear magnetic resonance spectroscopy, X-ray photoelectron spectroscopy, and size exclusion chromatography of the polyacrylamides after cleavage from the cellulose chains. The number-average molecular weights, Mn, of the cleaved polymers ranged from 1100 to 1600 g mol-1 for PDEAAm (dispersity D = 1.4-1.8) and from 1200 to 2600 g mol -1 for PNIPAM (D = 1.7-2.1). The LCST behavior of the cellulose-graft-copolymers was studied via the determination of cloud point temperatures, evidencing that the thermoresponsive properties of the hybrid materials could be finely tuned between 18 and 26 °C for PDEAAm and between 22 and 26 °C for PNIPAM side chains. © 2014 American Chemical Society.

Collagen-induced arthritis (CIA), the classical animal model for experimental arthritis, resembles human rheumatoid arthritis in several aspects. However, the most widely used method of inducing CIA utilizes Freund's adjuvants, which can skew the elicited immune responses and also pose toxicity problems. This unit describes a new method of inducing CIA using a well defined stimuli-responsive synthetic polymer, poly-N-isopropylacrylamide-based adjuvant, mixed with the joint cartilage protein collagen type II (CII). PNiPAAm as an adjuvant is biodegradable and biocompatible, and does not skew immune responses. Thus, it is helpful in the development of arthritis models for studying antigen and tissue -specific autoimmune responses in an unbiased manner. This model is valuable for analyzing disease pathways, positional identification of genes regulating arthritis, validation of existing therapies, and exploring new therapeutic targets. Furthermore, this newly developed PNiPAAm adjuvant allows investigation of disease induction using specific autoantigens in several autoimmune diseases independently of toll-like receptors, as well as optimization of vaccine delivery systems for infectious diseases. © 2014 John Wiley & Sons, Inc.

Collagen-induced arthritis (CIA), the classical animal model for experimental arthritis, resembles human rheumatoid arthritis in several aspects. However, the most widely used method of inducing CIA utilizes Freund's adjuvants, which can skew the elicited immune responses and also pose toxicity problems. This unit describes a new method of inducing CIA using a well defined stimuli-responsive synthetic polymer, poly-N-isopropylacrylamide-based adjuvant, mixed with the joint cartilage protein collagen type II (CII). PNiPAAm as an adjuvant is biodegradable and biocompatible, and does not skew immune responses. Thus, it is helpful in the development of arthritis models for studying antigen and tissue -specific autoimmune responses in an unbiased manner. This model is valuable for analyzing disease pathways, positional identification of genes regulating arthritis, validation of existing therapies, and exploring new therapeutic targets. Furthermore, this newly developed PNiPAAm adjuvant allows investigation of disease induction using specific autoantigens in several autoimmune diseases independently of toll-like receptors, as well as optimization of vaccine delivery systems for infectious diseases. © 2014 John Wiley & Sons, Inc.

The efficient and easily applicable surface modifying system for textiles can be created by using a specific polymeric form - hydrogel. Hydrogels exhibit the volume phase-transition property (swelling and shrinking) that can be triggered by various external stimuli (temperature, pH, humidity etc.), depending on the responsive properties of the polymers they are made of. However, after their incorporation into the textile material, surface modifying systems (SMS) must exhibit their responsive properties without screening the regular performance of the textile. This requirement is successfully fulfilled by the use of micro- or nano-sized hydrogels. Through this approach, the new added-value textile material can be created containing fibres that maintain advantageous conventional properties (e.g. mechanical strength, flexibility and wear comfort) but with advanced functionalities and/or environmental responsiveness implemented by the modification of a very thin surface layer of the material., Primenom jedne vrlo specifične forme polimera - hidrogela - moguće je kreirati efikasan i lako primenljiv sistem za modifikovanje površine tekstilnog materijala. Osnovno svojstvo hidrogela je da pokazuje zapreminsko/fazni prelaz (bubrenje i skupljanje) koji može biti iniciran različitim spoljnim stimulansima (pH, temperatura, vlažnost, itd.), što zavisi od svojstava polimera od kojih je formiran hidrogel. Važno je imati na umu da, posle inkorporacije u tekstilni materijal, sistem za modifikovanje površine (SMP) mora da zadrži mogućnost reakcije na spoljne stimulanse a da njegovo prisustvo istovremeno ne utiče negativno na regularna svojstva i ponašanje tekstilnog materijala. Ovaj zahtev se uspešno može ispuniti korišćenjem hidrogelova sa veličinom čestica u mikro- ili nano-oblasti. Prikazana rešenja omogućuju stvaranje novih tekstilnih materijala sa dodatnom vrednošću, koji istovremeno zadržavaju svoja pozitivna konvencionalna svojstva (kao npr.: mehanička jačina; fleksibilnost; komfor) i poseduju dodatnu funkcionalnost i/ili osetljivost na spoljne stimulanse, što je implementirano putem modifikovanja vrlo tankog površinskog sloja materijala.

The efficient and easily applicable surface modifying system for textiles can be created by using a specific polymeric form - hydrogel. Hydrogels exhibit the volume phase-transition property (swelling and shrinking) that can be triggered by various external stimuli (temperature, pH, humidity etc.), depending on the responsive properties of the polymers they are made of. However, after their incorporation into the textile material, surface modifying systems (SMS) must exhibit their responsive properties without screening the regular performance of the textile. This requirement is successfully fulfilled by the use of micro- or nano-sized hydrogels. Through this approach, the new added-value textile material can be created containing fibres that maintain advantageous conventional properties (e.g. mechanical strength, flexibility and wear comfort) but with advanced functionalities and/or environmental responsiveness implemented by the modification of a very thin surface layer of the material., Primenom jedne vrlo specifične forme polimera - hidrogela - moguće je kreirati efikasan i lako primenljiv sistem za modifikovanje površine tekstilnog materijala. Osnovno svojstvo hidrogela je da pokazuje zapreminsko/fazni prelaz (bubrenje i skupljanje) koji može biti iniciran različitim spoljnim stimulansima (pH, temperatura, vlažnost, itd.), što zavisi od svojstava polimera od kojih je formiran hidrogel. Važno je imati na umu da, posle inkorporacije u tekstilni materijal, sistem za modifikovanje površine (SMP) mora da zadrži mogućnost reakcije na spoljne stimulanse a da njegovo prisustvo istovremeno ne utiče negativno na regularna svojstva i ponašanje tekstilnog materijala. Ovaj zahtev se uspešno može ispuniti korišćenjem hidrogelova sa veličinom čestica u mikro- ili nano-oblasti. Prikazana rešenja omogućuju stvaranje novih tekstilnih materijala sa dodatnom vrednošću, koji istovremeno zadržavaju svoja pozitivna konvencionalna svojstva (kao npr.: mehanička jačina; fleksibilnost; komfor) i poseduju dodatnu funkcionalnost i/ili osetljivost na spoljne stimulanse, što je implementirano putem modifikovanja vrlo tankog površinskog sloja materijala.

In situ surface plasmon resonance (SPR) and quartz crystal microbalance (QCM) measurements have been employed to measure the adsorption kinetics and absolute adsorbed amount of the poly(N-isopropyl acrylamide) (pNIPAM) from bulk aqueous solution onto a hydrophobized gold substrate. The adsorption was carried out at 31 degreesC, which is just below the lower critical solution temperature of pNIPAM in water. We find that the shift in the coupling angle of the surface plasmon (proportional to the optical thickness) and the shift in the resonance frequency of the quartz crystal (proportional to the acoustic thickness) increase in parallel for most of the adsorption. Also, the change of dissipation is proportional to the change in frequency. These observations suggest that the buildup of the polymer layer proceeds via growth in thickness rather than by densification of a layer with constant thickness. We interpret this finding in the sense that the dense high-temperature phase wets the hydrophobic gold surface. The wetting layer has a fixed density and grows in thickness. In addition, the QCM has been used to study the temperature-induced conformational change for pNIPAM around the critical temperature. It was found that the technique was able to monitor additional adsorption that occurs when crossing the critical point, which was due to bulk phase separation. Desorption was also noted when crossing the critical point from the opposite direction, and for the given system the process was entirely reversible., QC 20100525

A novel approach of controlled drug delivery using thermosensitive polymers is developed in this paper. The drug release occurs at physiological temperature, at which the polymer is normally not soluble, and no medium temperature changes are required to bring about the delivery. For this purpose benefit is taken from the specific binding properties of some anionic surfactants and poly(N-isopropylacrylamide) (PNIPAAm) in order to modify the dissolution properties of PNIPAAm and of a copolymer with N-vinyl-acetamide (NVA), and so to induce the release of a drug contained in compression coated tablets. The influence of surfactant type and amount on the drug release rates and lag times from tablets coated with PNIPAAm or with the copolymer are discussed. It was found that the lag time is influenced by the surfactant species and amount. When use is made of a copolymer as coating agent, it is possible to bring about the release of the drug by incorporating only a very small amount (as low as 2%) of sodium dodecyl sulfate (SDS) in the coating. © 2002 Elsevier Science B.V. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

A novel approach of controlled drug delivery using thermosensitive polymers is developed in this paper. The drug release occurs at physiological temperature, at which the polymer is normally not soluble, and no medium temperature changes are required to bring about the delivery. For this purpose benefit is taken from the specific binding properties of some anionic surfactants and poly(N-isopropylacrylamide) (PNIPAAm) in order to modify the dissolution properties of PNIPAAm and of a copolymer with N-vinyl-acetamide (NVA), and so to induce the release of a drug contained in compression coated tablets. The influence of surfactant type and amount on the drug release rates and lag times from tablets coated with PNIPAAm or with the copolymer are discussed. It was found that the lag time is influenced by the surfactant species and amount. When use is made of a copolymer as coating agent, it is possible to bring about the release of the drug by incorporating only a very small amount (as low as 2%) of sodium dodecyl sulfate (SDS) in the coating. © 2002 Elsevier Science B.V. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

Poly-N-isopropylacrylamide (PNIPAAm) thermosensibility makes this polymer a very attractive candidate for controlled drug delivery systems. The polymer possesses a lower critical solution temperature (LCST) which was found to be around 32°C in pure water, but which can be affected by the medium composition, i.e. presence of salts or surfactants. The knowledge of the effects of such substances on the LCST is very important while using PNIPAAm as a controlled drug delivery agent. The influence of a number of physiological and non-physiological salts and surfactants has been studied. The results obtained show that the addition of salts provokes an important decrease of the LCST of the polymer (salting out effect). A strong influence of the valence and of the size of the anions of the halide group was found. As to the surfactants, according to their type and concentration, a decrease or an increase of the LCST or even no effect at all were found. The effect of the GI secretions on the PNIPAAm phase separation temperature is also discussed. © 2001 Elsevier Science B.V., SCOPUS: ar.j, info:eu-repo/semantics/published

Poly-N-isopropylacrylamide (PNIPAAm) thermosensibility makes this polymer a very attractive candidate for controlled drug delivery systems. The polymer possesses a lower critical solution temperature (LCST) which was found to be around 32°C in pure water, but which can be affected by the medium composition, i.e. presence of salts or surfactants. The knowledge of the effects of such substances on the LCST is very important while using PNIPAAm as a controlled drug delivery agent. The influence of a number of physiological and non-physiological salts and surfactants has been studied. The results obtained show that the addition of salts provokes an important decrease of the LCST of the polymer (salting out effect). A strong influence of the valence and of the size of the anions of the halide group was found. As to the surfactants, according to their type and concentration, a decrease or an increase of the LCST or even no effect at all were found. The effect of the GI secretions on the PNIPAAm phase separation temperature is also discussed. © 2001 Elsevier Science B.V., SCOPUS: ar.j, info:eu-repo/semantics/published