Mechanical and physico-chemical characterization of cyclodextrin finished polyamide fibers

Polymerized Molecular Receptors as Adsorbents to Remove Micropollutants from Water

Organic micropollutants (MPs) are increasing in number and concentration in water systems as a result of human activities. Often from human origin, these micropollutants build up in the environment because organisms lack the mechanisms to metabolize these substances, which cause negative health, ecological, and economic effects. Adsorption-based remediation processes for these compounds often rely on activated carbon materials. However, activated carbons are ineffective against certain MPs, exhibit low removal efficiencies in the presence of common aqueous matrix constituents, and require energy-intensive activation and regeneration processes. To overcome the deficiencies of traditional technologies, novel adsorbents based on molecular receptors offer promising alternative solutions. This Account describes the recent development of polymer adsorbents based on molecular receptors for removing trace organic chemicals from water. Polymer networks based on molecular receptors have high binding affinities for many MPs but, unlike activated carbons, have a specific molecule-binding mechanism that prevents these polymers from being fouled by matrix constituents such as natural organic matter. The size and hydrophobic pocket of the β-cyclodextrin receptor preferentially adsorbs target molecules such as organic micropollutants in the presence of matrix constituents, and the nature of the cross-linker tunes the binding affinity and selectivity of the adsorbent for specific classes of MPs, including those of varying charge and hydrophobicity. β-cyclodextrin polymers also exhibit rapid adsorption kinetics and are easily regenerated. This Account details β-cyclodextrin polymers made with three different cross-linkers, including a polymer that is postsynthetically transformed from a negatively charged polymer to a positively charged polymer to invert the polymer's micropollutant adsorption profile. Morphological constraints have so far limited these cross-linked polymers' ability to be used in commercial applications, but two methods to create larger and more uniformly sized particles for use in flow-through applications are described here. β-Cyclodextrin polymers are useful for trapping organic micropollutants such as bisphenol A, perfluorooctanoic acid, and many kinds of pharmaceuticals and pesticides, but their binding pockets are too large to capture micropollutants that are small or of high polarity. Other molecular receptors such as resorcinarene cavitands can target lower-molecular-weight MPs, including halomethane disinfection byproducts and industrial solvents, that are not bound strongly by β-cyclodextrins. These materials demonstrate the potential of expanding the library of polymers based on molecular receptors. Overall, these emerging adsorbents show promise for the removal of legacy and emerging MPs from water, as well as the ability to rationally tune the adsorbent's structure to target the most persistent and toxic MPs.

Water-soluble cationic poly(β-cyclodextrin-co-guanidine) as a controlled vitamin B2delivery carrier

Vitamin B₂(VB₂) is effectively incorporated into novel water-soluble cationic β-cyclodextrin (β-CD) polymers in order to improve its physiochemical properties.

Cyclodextrin and maltodextrin finishing of a polypropylene abdominal wall implant for the prolonged delivery of ciprofloxacin

The aim of this work was to develop a polypropylene (PP) artificial abdominal wall implant for the prolonged release of ciprofloxacin (CFX). This sustained release effect was obtained by functionalization of the textile mesh with citric acid and hydroxypropyl-γ-cyclodextrin (HPγCD) or maltodextrin (MD). In both cases the textile finishing reaction yielded a cyclo- or malto-dextrin crosslinked polymer coating the fibers. The modified supports were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry and scanning electron microscopy. The sorption capacities and the kinetics of CFX release were studied by batch tests coupled with spectrophotometric assays. Microbiological assays were carried out on Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli, while proliferation and viability tests used fibroblasts. The main results were as follows. (i) Due to the differences between the range of temperature of thermal degradation of the (cyclo)dextrins polymers and of the PP fibers TGA was a reliable method for quantifying the degree of functionalization of the textiles. (ii) Both modified supports showed improved sorption/desorption capacities for CFX, compared with the virgin mesh. The HPγCD-finished support showed an increased sorption capacity and a lower release rate of CFX compared with the MD modified support. (iii) Microbiological assays confirmed the latter result, with greater sustained antibacterial activity of the HPγCD treated support. These experiments have demonstrated the role of the cyclodextrin cavity in interactions with CFX: the antibiotic was not only adsorbed via hydrogen and acid-base interactions with the polyCTR-HPγCD network, but also via host-guest complexation. (iv) Biological tests revealed a slight decrease in fibroblast proliferation after 6 days on the modified supports, but cell viability tests showed that this was not due to toxicity of the (cyclo)dextrin polymer coatings.

Comparative study of polymer containing beta-cyclodextrin and -COOH for adsorption toward aniline, 1-naphthylamine and methylene blue

Three different polymers P1, P2 and P3 (P1 containing both beta-CD and -COOH, P2 containing beta-CD and P3 containing -COOH) were synthesized and applied to adsorption toward aniline, 1-naphthylamine and methylene blue. The concentrations (C) before and after adsorption were determined and the adsorption capacities (q) of P1, P2 and P3 were calculated. The maximum adsorption capacities (q(max)) toward aniline: q(max) (P1)=104 micromol g(-1), q(max) (P2)=14.9 micromol g(-1) and q(max) (P3)=53.1 micromol g(-1); toward 1-naphthylamine: q(max) (P1)=184 micromol g(-1), q(max) (P2)=53.8 micromol g(-1) and q(max) (P3)=125 micromol g(-1); toward methylene blue: q(max) (P1)=200 micromol g(-1), q(max) (P2)=12.7 micromol g(-1) and q(max) (P3)=215 micromol g(-1). P1 exhibited remarkable adsorption toward all the three adsorbates. P2 was almost equal to P1 in adsorption toward methylene blue, but was less efficient than P1 in adsorption toward aniline and 1-naphthylamine. P3 also exhibited considerable adsorption toward aniline and 1-naphthylamine, but was inefficient toward methylene blue. P1 was obtained from nontoxic materials and through environment friendly procedures, so it was potentially an efficient and green adsorbent for water purification.

Chemical, biological and microbiological evaluation of cyclodextrin finished polyamide inguinal meshes

This study describes the use of cyclodextrins (CDs) as a finishing agent of polyamide (PA) fibers used in order to obtain inguinal meshes with improved antibiotic delivery properties. The finishing process involved polymerization between citric acid and CDs, which yielded a cross-linked polymer that physically adhered to the surface of PA fibers. This permanent functionalization was characterized by evaluating the damping property with a polar liquid (glycerol) via the drop contact angle method for various rates of modification of the fabrics. The biological and microbiological effects of the PA, which were functionalized with hydroxypropylated derivate of gamma-CD (HP-gamma-CDs) and charged with ciprofloxacin (CFX), were evaluated by cell culture assays. We observed a good adhesion and proliferation of fibroblastic cells (NIH3T3) after 3 and 6 days and no detectable toxicity of the modified substrate. The in vitro antibacterial activity of the HP-gamma-CD grafted PA fabrics charged with CFX against the bacteria Staphylococcus aureus, Staphylococcus epidermidis and Escherichia coli was greatly superior to that of the virgin sample within a 24h batch experiment in human blood plasma medium. In conclusion, these results from our study offer an insight into the efficient performance of CDs as drug delivery systems for multiple applications in the fields of biomaterials and medical textiles.