Curcumin (1,7-bis-(4-hydroxy-3-methoxyphenyl)-hepta-1,6-diene-3,5-dione) is a natural lipophilic polyphenol that exhibits significant pharmacological effects in vitro and in vivo through various mechanisms of action. Numerous studies have identified and characterised the pharmacokinetic, pharmacodynamic, and clinical properties of curcumin. Curcumin has an anti-inflammatory, antioxidative, antinociceptive, antiparasitic, antimalarial effect, and it is used as a wound-healing agent. However, poor curcumin absorption in the small intestine, fast metabolism, and fast systemic elimination cause poor bioavailability of curcumin in human beings. In order to overcome these problems, a number of curcumin formulations have been developed. The aim of this paper is to provide an overview of recent research in biological and pharmaceutical aspects of curcumin, methods of sample preparation for its isolation (Soxhlet extraction, ultrasound extraction, pressurised fluid extraction, microwave extraction, enzyme-assisted aided extraction), analytical methods (FTIR, NIR, FT-Raman, UV-VIS, NMR, XRD, DSC, TLC, HPLC, HPTLC, LC-MS, UPLC/Q-TOF-MS) for identification and quantification of curcumin in different matrices, and different techniques for developing formulations. The optimal sample preparation and use of an appropriate analytical method will significantly improve the evaluation of formulations and the biological activity of curcumin.

Curcumin comes from the plant species Curcuma longa and shows numerous pharmacological activities. There are numerous curcumin formulations with gels or cyclodextrins in order to increase its solubility and bioavailability. This paper presents the formulation of complex of curcumin with 2-hydroxypropyl-β-cyclodextrin in a thermosensitive hydrogel, based on N-isopropylmethacrylamide and N-isopropylacrylamide with ethylene glycol dimethacrylate as a crosslinker. The product was characterized by chemical methods and also by FTIR, HPLC, DSC, SEM, XRD. The results show that synthesis was successfully done. With an increase in the quantity of crosslinker in the hydrogels, the starting release and the release rate of curcumin from the formulation of the complex with hydrogels decreases. The release rate of curcumin from the gel complex formulation is constant over time. It is possible to design a formulation that will release curcumin for more than 60 days. In order to determine the mechanism and kinetics of curcumin release, various mathematical models were applied by using the DDSolver package for Microsoft Excel application. The Korsmeyer-Peppas model best describes the release of curcumin from the gel formulation of the complex, while the values for the diffusion exponent (0.063–0.074) shows that mechanism of the release rate is based on diffusion.

Poly(N-isopropylmethacrylamide) (p(NiPMAm)) is one of the lesser known homopolymers that has significant potential for designing new “intelligent” materials. The aims of this work were the synthesis a series of cross-linked p(NiPMAm) hydrogels by the free radical polymerization method and the application of gamma-ray radiation for additional cross-linking. The synthesized p(NiPMAm) hydrogels were structurally characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The amount of unreacted monomers was analyzed using high pressure liquid chromatography (HPLC) to evaluate conversion of monomers into polymers. The swelling behavior was monitored in dependence of pH and temperature changes. The previous aim of gamma-ray radiation was the further the cross-linkage of the obtained hydrogel sample in the gelatinous, paste-like state, but the gamma-ray radiation caused decomposition. After absorbing irradiation doses, they transformed into the liquid phase. The results obtained by the gel permeation chromatography (GPC) method indicated that only oligomers and monomers were present in the irradiated liquid material, without molecules with a higher average molar mass, i.e., that the decomposition of the hydrogels occurred. Additionally, the irradiated liquid material was analyzed using the static headspace gas chromatography mass spectrometry (HSS-GC/MS) and gas chromatography/flame ionization detection (HSS-GC/FID) methods. The presence of unchanged initiator molecule and a dominant amount of four new molecules that were different from homopolymers and the reactant (monomer and cross-linker) were determined.

N-isopropylacrylamide and methacrylic acid were copolymerized by a free radical polymerized mechanism. The obtained hydrogel poly(N-isopropylacrylamide-co-methacrylic acid) hydrogels, poly(NIPAM-co-MAA), were utilized as sorbent material for removal Cr(VI), Mn(II), and Pb(II) ions from simulated aqueous solutions. Hydrogel structures before and after heavy metal sorption are characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The swelling results indicate that poly(NIPAM-co-MAA) hydrogels are pH- and temperature-sensitive and have high swelling reversibility through three swelling/contraction cycles. The studied parameters of heavy metal sorption include the effect of pH, the initial concentration of heavy metal, the effect of temperature, and the desorption of metal ions. The maximum sorption capacities of poly(NIPAM-co-MAA) hydrogels were determined at pH 4.5 and 25 °C, and they are, for Cr(VI), Mn(II), and Pb(II) ions, 289.35 mg/g, 190.59 mg/g, and 349.71 mg/g, respectively. The pseudo-second-order model and the Langmuir adsorption isotherm best describe the sorption of heavy metal ions onto hydrogels. The removal of heavy metals is an exothermic reaction, and the interaction mechanism between the metal and the hydrogel is primarily physical in nature. Results of three sorption/desorption cycles show a good desorption ratio and sorption capacity of poly(NIPAM-co-MAA) hydrogels.

Copolymeric hydrogels of poly(N-isopropylmethacrylamide-co-N-isopropylacrylamide), p(NIPMAM/NIPAM), are synthesized by radical polymerization of N-isopropylmethacryl-amide (NIPMAM) and N-isopropylacrylamide (NIPAM) monomers by using the cross-linker ethylen glycol dimethacrylate (EGDM). The synthesized copolymeric p(NIPMAM/NIPAM) hydrogels, starting monomers and the cross-linker were structurally characterized by using Fourier transform infrared spectroscopy (FTIR). The amounts of residual reactants in the synthesized hydrogels were determined by high-pressure liquid chromatography (HPLC). Swelling of p(NIPMAM/NIPAM) hydrogels was investigated in relation to the temperature and pH value of the solution. The obtained values of residual monomer quantities are within acceptable limits and in the range from 2.69 to 5.25 mg g-1 for NIPMAM and 14.55 to 30.80 mg g-1 for NIPAM. The synthesized p(NIPMAM/NIPAM) hydrogels are negatively thermosensitive. The most common mechanisms of transport of a swelling solution in p(NIPMAM/NIPAM) hydrogels are polymer chain relaxation, (Case III), and the anomalous type of diffusion (non-Fickian diffusion). The maximal equilibrium swelling degree of 51.19 was reached by the p(NIPMAM/NIPAM) hydrogel with 1.5 mol% of EGDM at the temperature of 25?C and pH 4, whereas the lowest one of 0.98 was exhibited by the hydrogel with 3 mol% of EGDM at the temperature of 80?C and pH 7. Due to their low content of residual reactants and a satisfactory degree of swelling at various pH values, synthesized p(NIPMAM/NIPAM) hydrogels can be applied as carriers for the controlled release of pharmaceutically active substances.

The aim of this study is to investigate the possibility of using electrospun polylactide (PLA) fibers as a carrier of the phytoestrogen biochanin A. Polylactide fibers were prepared with different contents of biochanin A by using an electrospinning method at specific process parameters. The obtained electrospun polylactide fibers, as carriers of biochanin A, were characterized by means of different methods. The presented results showed that the mechanical properties of PLA have not changed significantly in the presence of biochanin A. Scanning electron microscopy showed that the fine fiber structure is retained without visible deformations and biochanin A crystals on the surface of the fibres. The analysis by infrared spectroscopy showed that there are no strong interactions between polylactide and biochanin A molecules, which is a good prerequisite for the diffusion release of biochanin A from PLA fibers.The release of biochanin A from PLA fibers in buffer solution pH 7.4 at 37 °C was monitored by applying the HPLC method. The rate and time of the release of biochanin A from PLA fibers is in correlation with the amount of the active ingredient in the matrix of the carrier and follows zero-order kinetics. PLA fibers with biochanin A exhibit concentration-dependent activity on proliferation and migration of L929 fibroblasts in direct culture system in vitro, and proved to be suitable for a potential formulation for use in wound healing.