Soft Poly(N-vinylcaprolactam) Based Aqueous Particles.

Soft nanoparticles are an important class of material with potential to be used as carriers of active compounds. Swollen, penetrable particles can act as a host for the active ingredients and provide stability, stimuli-responsiveness and recyclability for the guest. Thermoresponsive colloidal gel particles are especially attractive for such applications due to the extremely soft structure, size and responsiveness. Poly(N-vinylcaprolactam) (PNVCL) is a much studied, popular thermoresponsive polymer. The polymer has low toxicity and the phase transition temperature is close to body temperature. During the phase transition, the polymer becomes less soluble, the particle expels a large part of water and the particle collapses to a more compact form. The diffusion of material in and from the particles is largely affected by this transition.  As the solubility of the polymer changes, so do the interactions with the loaded compound.  This feature article focuses on the synthetic methods, properties and applications of soft PNVCL particles.

Robust, anti-biofouling 2D nanogel films from poly(N-vinyl caprolactam-co-vinylimidazole) polymers.

In analogy with adsorbed protein films, we have fabricated a family of 2D nanofilms composed of poly(N-vinyl caprolactam-co-vinylimidazole) (PNVCL) nanogels. NVCL was copolymerized with 1-vinylimidazole (VIM), and then cross-linked with α,ω-dibromoalkanes with 2 to 8 carbons via quaternization to form the nanogels. The swelling ratio of the gels was precisely controlled by regulating the inter-chain spacing of the polymers at the level of the carbon atom chain length of the cross-linker. The short-chain alkanes used are relatively rigid and their dimensions provide an accurate estimate of the chain spacing in the nanogels. It was shown that small differences in the carbon atom number of the cross-linking agent led to significant differences in the mechanical properties of the nanogels, in particular in the softness, deformability, and contact area (in film form), all of which increased with increasing carbon number. Films of the softer gels not only showed good adhesion to a number of substrates, but were also mechanically robust. In addition, the films showed excellent light transmission and nontoxicity to L929 cells. Nanogels of intermediate softness were shown to inhibit the adhesion of bacteria and human umbilical vein smooth muscle cells (HUVSMCs), and to be resistant to the adsorption of the plasma protein fibrinogen, indicating strong anti-biofouling properties. Gels that were either too stiff or too soft showed somewhat weaker anti-fouling activity in terms both of HUVSMCs adhesion and protein adsorption.

Preparation of LCST regulable DES-lignin-g-PNVCL thermo-responsive polymer by ARGET-ATRP.

To expand the field of high-value utilization of lignin. The degraded deep eutectic solvent lignin-grafted poly (N-Vinyl caprolactam) (DES-lignin-g-PNVCL) was synthesized by modified DES-lignin and NVCL via the combination of activators regenerated by electron transfer-atom transfer radical polymerization (ARGET-ATRP). Fourier transform infrared spectroscopy (FT-IR), 1H NMR, X-ray electron spectroscopy (XPS), dynamic light scattering (DLS), differential scanning calorimeter (DSC) were used to characterize the structure and performance of DES-lignin-g-PNVCL. The results indicated that the PNVCL and DES-lignin-g-PNVCL were successfully prepared by ARGET-ATRP. The lowest critical solution temperature (LCST) of PNVCL was 35.75 °C. Due to different strength of hydrogen bond, different energies were required, so the LCST of the polymer can be regulated. When the molar ratio of phenolic hydroxyl group in degraded DES-lignin to 2-bromoisobutyryl bromide (BiBB) was increased from 1:1 to 1:7, the grafting rate of DES-lignin-Br was increased from 32.87% to 60.84%, and the LCST of DES-lignin-g-PNVCL was decreased from 47.98 °C to 27.88 °C. The LCST of DES-lignin-g-PNVCL was increased from 30.98 °C to 44.64 °C when the addition amount of DES-lignin-Br was increased from 20 mg to 200 mg. The LCST of DES-lignin-g-PNVCL was increased from 27.20 °C to 39.86 °C when the ratio of DMF/water was increased from 1:4 to 4:1. The LCST of DES-lignin-g-PNVCL was decreased from 52.10 °C to 31.02 °C when the concentration of DES-lignin-g-PNVCL was increased from 0.5 mg/mL to 2.5 mg/mL. The equation represented the relationship between LCST and influencing factors was obtained, the good predictability provided a tactics for preparing desired LCST thermo-responsible polymer.

Thermochemistry of Solution, Solvation, and Hydrogen Bonding of Cyclic Amides in Proton Acceptor and Donor Solvents. Amide Cycle Size Effect.

In the present work, the thermochemistry of solution, solvation, and hydrogen bonding of cyclic amides in proton acceptor (B) and proton donor (RXH) solvents were studied. The infinite dilution solution enthalpies of δ-valerolactam, N-methylvalerolactam, ε-caprolactam, and N-methylcaprolactam were measured at 298.15 K. The solvation enthalpies of cyclic amides were calculated based on the measured solution enthalpies and sublimation/vaporization enthalpies from literature. The enthalpies of hydrogen bonding between cyclic amides and proton acceptor and donor solvents were then calculated as a difference between the total solvation enthalpy and the non-specific contribution. The latter was estimated via two different approaches in proton donor and proton accepting solvents. The effect of the cycle size on the strength of hydrogen bonding of the cyclic amides in solution is discussed.

Catalytic and structural properties of ATP-dependent caprolactamase from Pseudomonas jessenii.

Caprolactamase is the first enzyme in the caprolactam degradation pathway of Pseudomonas jessenii. It is composed of two subunits (CapA and CapB) and sequence-related to other ATP-dependent enzymes involved in lactam hydrolysis, like 5-oxoprolinases and hydantoinases. Low sequence similarity also exists with ATP-dependent acetone- and acetophenone carboxylases. The caprolactamase was produced in Escherichia coli, isolated by His-tag affinity chromatography, and subjected to functional and structural studies. Activity toward caprolactam required ATP and was dependent on the presence of bicarbonate in the assay buffer. The hydrolysis product was identified as 6-aminocaproic acid. Quantum mechanical modeling indicated that the hydrolysis of caprolactam was highly disfavored (ΔG0 '= 23 kJ/mol), which explained the ATP dependence. A crystal structure showed that the enzyme exists as an (αß)2 tetramer and revealed an ATP-binding site in CapA and a Zn-coordinating site in CapB. Mutations in the ATP-binding site of CapA (D11A and D295A) significantly reduced product formation. Mutants with substitutions in the metal binding site of CapB (D41A, H99A, D101A, and H124A) were inactive and less thermostable than the wild-type enzyme. These residues proved to be essential for activity and on basis of the experimental findings we propose possible mechanisms for ATP-dependent lactam hydrolysis.

Electrospun polyamide-6/chitosan nanofibers reinforced nano-hydroxyapatite/polyamide-6 composite bilayered membranes for guided bone regeneration.

Periodontal defect poses a significant challenge in orthopedics. Guided Bone Regeneration (GBR) membrane is considered as one of the most successful methods applied to reconstruct alveolar bone and then to achieve periodontal defect repair/regeneration. In this paper, a novel polyamide-6/chitosan@nano-hydroxyapatite/polyamide-6 (PA6/CS@n-HA/PA6) bilayered tissue guided membranes by combining a solvent casting and an electrospinning technique was designed. The developed PA6/CS@n-HA/PA6 composites were characterized by a series of tests. The results show that n-HA/PA6 and electrospun PA6/CS layers are tightly bound by molecular interaction and chemical bonding, which enhances the bonding strength between two distinct layers. The porosity and adsorption average pore diameter of the PA6/CS@n-HA/PA6 membranes are 36.90 % and 22.61 nm, respectively. The tensile strength and elastic modulus of PA6/CS@n-HA/PA6 composites are 1.41 ± 0.18 MPa and 7.15 ± 1.09 MPa, respectively. In vitro cell culture studies demonstrate that PA6/CS@n-HA/PA6 bilayered scaffolds have biological safety, good bioactivity, biocompatibility and osteoconductivity.

The use of ion mobility time-of-flight mass spectrometry to assess the migration of polyamide 6 and polyamide 66 oligomers from kitchenware utensils to food.

Oligomers, are, in general, unknown components of the polymer. These oligomers can migrate from the polymer into the food and become a non-intentionally added substance to the food. In this work, ion mobility time-of-flight mass spectrometry has been used to identify oligomers migrating from kitchenware. The structure elucidation of oligomers from polyamide 6 and polyamide 66 was achieved through the analysis of accurate m/z values of adducts and collision cross section values of precursor ions together with high-energy fragmentation patterns. Additionally, a method to extract oligomers from sunflower oil, cooked beans, soup and whole milk has been developed. Extraction recoveries ranged from 87 to 102% and limits of detection were from 0.03 to 0.11 mg/kg. It was observed that the migration from kitchenware to real food was below the specified migration limit of 5 mg/kg. However, this limit was exceeded for food simulants, which therefore overestimated the oligomer migration.

Improving viral filtration capacity in biomanufacturing processes using aggregate binding properties of polyamide-6,6.

Virus retention filtration is a common step in modern biopharmaceutical manufacturing as it enables efficient removal of potential adventitious and endogenous viruses via size exclusion. Modern parvovirus retention filters have significantly improved fluxes and parvovirus retention in comparison to earlier versions of these filters. However, these filters may be more susceptible to premature fouling and require more effort for process optimization. Here, we demonstrate that polyamide-6,6 (nylon-6,6) membranes when used as prefilters can increase the capacity of these Parvovirus retentive filters that are less susceptible to premature fouling. We found that the mechanism of polyamide-mediated filtration improvement can be explained by the binding of monoclonal antibody (mAb) aggregates with a diameter of 20-100 nm, and we show that this mechanism is shared by other types of adsorptive prefilters. Finally, by the combination of mobile phase screening, additive spiking, and molecular dynamics simulations, we show that polyamide-6,6 removes mAb aggregates through hydrophobic interactions making its design space potentially complementary to other available prefilters. Our studies support the aggregate-mediated mechanism of flux decay during viral filtration and suggest that polyamide-6,6 could be considered as an alternative cost-effective option to extend the capacity of viral filters.

Coated electrospun polyamide-6/chitosan scaffold with hydroxyapatite for bone tissue engineering.

Polyamide-6 (PA6) is a synthetic polymer that bears resemblance to collagen in its backbone and has excellent stability in human body fluid. Chitosan (CS) with the similar structure to that of the polysaccharides existing in the extracellular matrix (ECM), has a more suitable biodegradation rate for the formation of new-bone. Electrospun fiber have nanoscale structure, high porosity and large specific surface area, can simulate the structure and biological function of the natural ECM. To meet the requirements of mechanical properties and biocompatibility of bone tissue engineering, electrospun PA6/CS scaffolds were fabricated by electrospinning technology. The mineralized PA6/CS scaffolds were obtained through immersion in 1.5× simulated body fluid (1.5SBF), which allowed the hydroxyapatite (HA) layer to grow into the thickness range under very mild reaction conditions without the need of a prior chemical modification of the substrate surface. The results showed that electrospun PA6/CS fibrous scaffolds in the diameter range of 60-260 nm mimic the nanostructure of the ECM. The tensile strength and modulus of 10PA6/CS fibrous scaffolds reach up to 12.67 ± 2.31 MPa and 95.52 ± 6.78 MPa, respectively. After mineralization, HA particles uniformly distributed on the surface of PA6/CS fibrous scaffolds in a porous honeycomb structure, and the content of mineral was about 40%. In addition, cell culture study indicated that the mineralized PA6/CS composite scaffolds were non-cytotoxic, and had a good biocompatibility and an ability to promote MC3T3-E1 cell attachment and proliferation.

Monitoring of priority pollutants chlorophenols in water and milk by headspace solid-phase microextraction based on electrospun polycaprolactam nanofibers decorated with cadmium oxide-carbon nanotubes.

Priority pollutants chlorophenols are broadly used chemicals that are persistent in the environment and causing serious human health hazards. The current study introduces a novel adsorbent for the extraction of chlorophenols from river water, surface water, and milk by headspace solid-phase microextraction coupled with gas chromatography. The adsorbent composite was prepared by blending polycaprolactam (nylon-6) mat and newly synthesized carbon nanotubes decorated with cadmium oxide nanoparticles followed by electrospinning technique to produce based nanofiber. The proposed nanofiber was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray diffraction techniques. The main parameters that affect extraction efficiency, including ionic strength, extraction time, desorption time, and extraction temperature, were investigated and optimized. The linear range was 0.05-5 ng/mL; the limits of detection (signal/noise=3) were 0.02-0.04 ng/mL. The relative recoveries for real samples (river water, surface water, and milk) were in the range of 84-114%.

Bioresponsive supramolecular hydrogels for hemostasis, infection control and accelerated dermal wound healing.

Injectable, drug-releasing hydrogel scaffolds with multifunctional properties including hemostasis and anti-bacterial activity are essential for successful wound healing; however, designing ideal materials is still challenging. Herein, we demonstrate the fabrication of a biodegradable, temperature-pH dual responsive supramolecular hydrogel (SHG) scaffold based on sodium alginate/poly(N-vinyl caprolactam) (AG/PVCL) through free radical polymerization and the subsequent chemical and ionic cross-linking. A natural therapeutic molecule, tannic acid (TA)-incorporated SHG (AG/PVCL-TA), was also fabricated and its hemostatic and wound healing efficiency were studied. In the AG/PVCL-TA system, TA acts as a therapeutic molecule and also substitutes as an effective gelation binder. Notably, the polyphenol-arm structure and diverse bonding abilities of TA can hold polymer chains through multiple bonding and co-ordinate cross-linking, which were vital in the formation of the mechanically robust AG/PVCL-TA. The SHG formation was successfully balanced by varying the composition of SA, VCL, TA and cross-linkers. The AG/PVCL-TA scaffold was capable of releasing a therapeutic dose of TA in a sustained manner under physiological temperature-pH conditions. AG/PVCL-TA displayed excellent free radical scavenging, anti-inflammatory, anti-bacterial, and cell proliferation activity towards the 3T3 fibroblast cell line. The wound healing performance of AG/PVCL-TA was further confirmed in skin excision wound models, which demonstrated the potential application of AG/PVCL-TA for skin regeneration and rapid wound healing.

Synthesis of cellulose microcrystals (CMC)/nylon 6,10 composite by incorporating CMC isolated from Pandanus ceylanicus.

The paper presents a novel candidate plant: Pandanus ceylanicus (PC) for cellulose extraction. The plant showed an average of 91.5 ±â€¯0.2 % of cellulose yield which is the highest yield for Pandanus species reported. Cellulose was extracted from the leaves of the plant by carrying out alkali and bleaching treatments, and cellulose microcrystals (CMC) were isolated from extracted cellulose fibers with sulphuric acid treatment. Chemical composition of PC leaves was investigated at different stages of treatment by using TAPPI standard methods. The extracted globular shaped CMC crystals had an average diameter less than a micro meter. Results revealed that PC leaves are an efficient source of micro-cellulose which result in a high yield than most lignocellulosic biomasses. The CMCs were successfully incorporated with nylon 6,10 by in-situ interfacial polymerization of sebacoyl chloride and hexamethylenediamine in the presence of CMC. The CMC/nylon 6,10 composite showed improved water absorption with low water retention time.

Nanodecoration of electrospun polymeric fibers with nanostructured silver coatings by ionized jet deposition for antibacterial tissues.

Silver-based nanomaterials are used as antibacterial agents in a number of applications, including wound dressing, where electrospun materials can effectively promote wound healing and tissue regeneration thanks to their biomimicry, flexibility and breathability. Incorporation of such nanomaterials in electrospun nonwovens is highly challenging if aiming at maximizing stability and antibacterial efficacy and minimizing silver detachment, without neglecting process straightforwardness and scalability. In this work nanostructured silver coatings were deposited by Ionized Jet Deposition (IJD) on Polylactic acid, a medical grade polyester-urethane and Polyamide 6,6 nanofibers. The resulting materials were thoroughly characterized to gain an in-depth view of coating morphology and substrate resistance to the low-temperature deposition process used. Morphology of silver coatings with well-cohesive grains having dimensions from a few tens to a few hundreds of nanometers was analyzed by SEM, TEM and AFM. TGA, DSC, FTIR and GPC showed that the polymers well withstand the deposition process with negligible effects on their properties, the only exception being the polylactic acid that resulted more susceptible to degradation. Finally, the efficacy against S. aureus and E. coli bacterial strains was demonstrated, indicating that electrospun fibers decorated with nanostructured silver by IJD represent a breakthrough solution in the field of antibacterial devices.

Thermoreversible Switchlike Electrocatalytic Reduction of Tizanidine Based on a Graphene Oxide Tethered Stimuli-Responsive Smart Surface Supported Pd Catalyst.

In this work, a graphene oxide (GRO)-based temperature-sensitive smart catalytic support material was developed by tethering biodegradable and hydrophilic poly(N-vinylcaprolactam) (PVCL) on a GRO (i.e., GRO-PVCL) surface. GRO-PVCL-supported palladium catalyst (i.e., Pd/GRO-PVCL) was then prepared for tizanidine (TZN) electroreduction. The impact of a temperature-sensitive smart surface on the electrochemical and electrocatalytic properties was examined. Moreover, when the large surface area, excellent electron transfer, and electrochemical catalysis abilities of GRO were combined with the responsive characteristics of PVCL, temperature-triggered reversible electrocatalysis of TZN with enhanced sensitivity has been proved. Results designated that GRO-PVCL exposed the hydrophilic surface at 20 °C, resulting in Pd NPs highly dispersed on the GRO-PVCL surface. Subsequently, the wettability of the Pd catalyst surface arbitrarily adapted to hydrophobicity at 40 °C, which highly enhanced the TZN reduction on the catalyst in electrochemical detection. The synergistic effect amid Pd and GRO-PVCL on Pd/GRO-PVCL improved the electrocatalytic activity of TZN. The detection of TZN with the Pd/GRO-PVCL modified electrode ranged from 0.02 to 276 µM with a low detection limit of 0.0015 µM at 40 °C. The Pd/GRO-PVCL modified electrode also possesses excellent stability, reproducibility, and anti-interference ability. Lastly, the modified electrode attained good recovery results in human urine and human plasma samples for the determination of TZN and also pharmacokinetics study in rat plasma.

Lysozyme/collagen multilayers layer-by-layer deposited nanofibers with enhanced biocompatibility and antibacterial activity.

Biological meshes have always posed a challenge in biological medicine, for which nanocomposites with enhanced biocompatibility and antibacterial activity may be beneficial. In this study, lysozyme (LY) and collagen (Col) were alternately deposited on silk fibroin (SF) and nylon 6 (N6) composite nanofibrous mats using a layer-by-layer (LBL) self-assembly technique. The mechanical properties, biocompatibility, and antibacterial activity of the LBL structured mats were characterized systematically to investigate the impact of the LBL process on the biological properties of SF/N6 nanofibrous mats. Our results showed that the effective deposition of LY and Col may affect the surface topography, mechanical properties, and wetting behavior of the SF/N6 nanofibrous mats. Moreover, LBL structured mats exhibited excellent biocompatibility and antibacterial properties. Among all the tested mats, those coated with 10 bilayers of LY and Col displayed the best biocompatibility, and relatively good mechanical and antibacterial properties. Thus, LBL structured mats, especially those with a 10 bilayer coating, are potentially valuable in clinical therapy for pelvic organ prolapse in the future.

Biomimetic Nylon 6-Baghdadite Nanocomposite Scaffold for Bone Tissue Engineering.

Nature creates soft and hard ingredients revealing outstanding properties by adjusting the ordered assembly of simple primarily components from the nano- to the macro-scale. To simulate the important features of native tissue architecture, wide researches are being performed to develop new biomimetic custom-made composite scaffolds for tissue engineering. Here, we introduced a three-dimensional (3D) biomimetic scaffold based on the cuttlefish bone (CB) as a sacrificial template for bone tissue engineering. By combination of nylon 6 (N6), various amounts of baghdadite (BG) nanopowder and sacrificial template CB, a novel nanocomposite scaffolds was successfully developed with hierarchical microstructure and open pores in the range size in long and minor axis of 153-253 µm and 39-70 µm, respectively, depending on the BG content. In addition, incorporation of BG improved the mechanical properties of the scaffolds. Noticeably, the compressive strength and compressive modulus enhanced from 0.47 ± 0.05 to 1.41 ± 0.25 MPa and from 3.16 ± 0.14 to 6.23 ± 0.3 MPa, respectively. Moreover, results demonstrated that the incorporation of BG nanoparticles in the N6 matrix significantly improved bioactivity in simulated body fluid and increased degradation rate of N6 scaffold. Additionally, 3D nanocomposite scaffolds disclosed meaningfully excellent cellular responses. It is envisioned that the provided N6-BG nanocomposite scaffold might be a promising candidate for bone tissue engineering applications.

Underutilized Agricultural Co-Product as a Sustainable Biofiller for Polyamide 6,6: Effect of Carbonization Temperature.

Polyamide 6,6 (PA66)-based biocomposites with low-cost carbonaceous natural fibers (i.e., soy hulls, co-product from soybean industry) were prepared through twin-screw extrusion and injection molding. The soy hull natural fiber was pyrolyzed at two different temperatures (500 °C and 900 °C denoted as BioC500 and BioC900 respectively) to obtain different types of biocarbons. The BioC500 preserved a higher number of functional groups as compared to BioC900. Higher graphitic carbon content was observed on the BioC900 than BioC500 as evident in Raman spectroscopy. Both biocarbons interact with the PA66 backbone through hydrogen bonding in different ways. BioC900 has a greater interaction with N-H stretching, while BioC500 interacts strongly with the amide I (C=O stretching) linkage. The BioC500 interrupts the crystallite growth of PA66 due to strong bond connection while the BioC900 promotes heterogeneous crystallization. Dynamic mechanical analysis shows that both biocarbons result in an increasing storage modulus and glass transition temperature with increasing content in the BioC/PA66 biocomposites over PA66. Rheological analysis shows that the incorporation of BioC900 results in decreasing melt viscosity of PA66, while the incorporation of BioC500 results in increasing the melt viscosity of PA66 due to greater filler-matrix adhesion. This study shows that pyrolyzed soy hull natural fiber can be processed effectively with a high temperature (>270 °C) engineering plastic for biocomposites fabrication with no degradation issues.

The role of osmolytes in the temperature-triggered conformational transition of poly(N-vinylcaprolactam): an experimental and computational study.

Biomedical industries are widely exploring the use of thermo-responsive polymers (TRPs) in the advanced development of drug delivery and in many other pharmaceutical applications. There is a great need to investigate the use of less toxic and more (bio-)compatible TRPs employing several additives, which could modify the conformational transition behavior of TRPs in aqueous solution. To move forward in this aspect, we have chosen the less toxic bio-based polymer poly(N-vinylcaprolactam) (PVCL) and three different methylamine-based osmolytes, trimethylamine N-oxide (TMAO), betaine and sarcosine, in order to investigate their particular interactions with the polymer segments in PVCL and therefore the corresponding changes in the thermo-responsive conformational behavior. Several biophysical techniques, UV-visible spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS) and laser Raman spectroscopy, as well as classical computer simulation methods such as molecular dynamics are employed in the current work. All the studied methylamines are found to favor the hydrophobic collapse of the polymer thus stabilizing the globular state of PVCL. Sarcosine is observed to cause the maximum decrease in lower critical solution temperature (LCST) of PVCL followed by TMAO and then betaine. The differences observed in the LCST values of PVCL in the presence of these molecules can be attributed to the different polymer-osmolyte interactions. The less sterically hindered N atom in the case of sarcosine causes a significant difference in the phase transition temperature values of PVCL compared to betaine and TMAO, where the nitrogen atom is buried by three methyl groups attached to it.

Glucose and Maltose Surface-Functionalized Thermoresponsive Poly(N-Vinylcaprolactam) Nanogels.

Soft nanoparticles are interesting materials due to their size, deformability, and ability to host guest molecules. Surface properties play an essential role in determining the fate of the particles in biological medium, and coating of the nanoparticles (and polymers) with carbohydrates has been found to be an efficient strategy for increasing their biocompatibility and fine-tuning other important properties such as aqueous solubility. In this work, soft nanogels of poly(N-vinylcaprolactam), PNVCL, were surface-functionalized with different glucose and maltose ligands, and the colloidal properties of the gels were analyzed. The PNVCL nanogels were first prepared via semibatch precipitation polymerization, where a comonomer, propargyl acrylate (PA), was added after preparticle formation. The aim was to synthesize "clickable" nanogels with alkyne groups on their surfaces. The nanogels were then functionalized with two separate azido-glucosides and azido-maltosides (containing different linkers) through a copper-catalyzed azide-alkyne cycloaddition (CuAAc) click reaction. The glucose and maltose bearing nanogels were thermoresponsive and shrank upon heating. Compared to the PNVCL-PA nanogel, the carbohydrate bearing ones were larger, more hydrophilic, had volume phase transitions at higher temperatures, and were more stable against salt-induced precipitation. In addition to investigating the colloidal properties of the nanogels, the carbohydrate recognition was addressed by studying the interactions with a model lectin, concanavalin A (Con A). The binding efficiency was not affected by the temperature, which indicates that the carbohydrate moieties are located on the gel surfaces, and are capable of interacting with other biomolecules independent of temperature. Thus, the synthesis produces nanogels, which have surface functions capable of biorelevant interactions and a thermoresponsive structure. These types of particles can be used for drug delivery.

Synthesis of chitosan-grafted-poly(N-vinylcaprolactam) coated on the thiolated gold nanoparticles surface for controlled release of cisplatin.

The gold nanoparticles surface was modified by thioglycolic acid ligand and their surface was coated by the chitosan-grafted-poly(N-vinylcaprolactam) (chitosan-g-PNVCL) copolymer. The cisplatin anticancer drug was loaded into the synthesized nanocarriers and its performance was investigated for the treatment of MCF-7 breast cancer cells in vitro. The synthesized nanoparticles were characterized using FTIR, DLS, TEM, SEM, EDX and TGA analysis. The lower critical solution temperature (LCST) of PNVCL/chitosan and PNVCL/chitosan coated gold nanoparticles were found to be 38 and 39 °C, respectively. The cisplatin loading efficiency, cisplatin release from nanoparticles at different temperatures and pH values as well as the pharmacokinetic studies were examined. The maximum cisplatin release from nanoparticles was achieved at T > LCST (42 °C) and pH of 5. The Korsemeyer-Peppas model was best described the cisplatin release from nanoparticles. The maximum MCF cell death was found to be 92% using cisplatin loaded-gold/TGA/chitosan-g-PNVCL nanoparticles under an induction heating system.