PVP In Solution Research Articles

Preparation and characterization of indomethacin loaded films by piezoelectric inkjet printing: a personalized medication approach

The purpose of this study was to investigate the application of piezoelectric inkjet technology in the preparation of custom-made indomethacin (IMC) films. Indomethacin solutions with and without PVP were printed onto polymeric sheets using a commercial inkjet printer. Drug loading was varied by selecting a machine parameter different dots per inches (DPIs). The printed patches were evaluated for particulate morphologies, drug loading, in vitro release and ex vivo skin permeation and anti-inflammatory effects using hind paw inflammation model. Calculated drug loaded in 2 × 2 cm2 patches of IMC of 96, 300, and 600 DPIs were in the range of 40, 60, and 65 μg, respectively. Patches loaded with IMC alcoholic solution showed crystalline structures observed by scanning electron microscopy and the addition of PVP in solution turned it to amorphous form. The drug release profile showed 60–70% of total drug released in 3 h. Permeation studies showed 40–50% of total drug loaded permeated through rat skin using Franz cells. Patches with higher printing density 600 DPI showed anti-inflammatory effect in hind paw inflammation model studies. This study has shown the potential of personalized medicine in which a calculated amount of drug can be delivered to patients by piezoelectric technology.

Dielectric relaxation strength and magnitude of dipole moment of poly(vinyl pyrrolidone)in polar solutions

Dielectric relaxation caused by the segmental motion of poly(vinyl pyrrolidone) (PVP) was observed in solutions at 25°C with various solvents, that is, chloroform, water, and mono- and dihydroxyl alcohols with dielectric constants ranging between 5 and 78. The relaxation strength of the segmental motion of PVP varies with the solvent. The magnitudes of the effective dipole moment of the repeat unit of PVP in solutions with various solvents calculated using the Onsager equation depends simply on the dielectric constant of the solvent at higher frequency.

Exposed crystal surface-controlled rutile TiO2 nanorods prepared by hydrothermal treatment in the presence of poly(vinyl pyrrolidone)

Rutile TiO2 particles with specific exposed crystal faces were prepared by hydrothermal treatment of titanium trichloride (TiCl3) solution with poly(vinyl pyrrolidone) (PVP) as a shape-control reagent. Crystal phase, shape, and size of TiO2 particles were found to be greatly dependent on the concentration of PVP in the solution. The exposed crystal surface of TiO2 was controlled by changing the concentration of PVP in TiCl3 and NaCl solutions. The prepared TiO2 particles were characterized by TEM, SEM, XRD, and specific surface area measurements. The photocatalytic activity of the synthesized TiO2 particles was evaluated by decomposition of acetaldehyde and toluene in gas phase. The synthesized TiO2 particles showed higher photocatalytic activity for degradation of acetaldehyde and toluene than did commercial TiO2 particles (MT-600B). However, the tendency of photocatalytic activities of the synthesized TiO2 particles for degradation of acetaldehyde in gas phase was different from that for degradation of toluene. From the photodeposition of Pt and PbO2, we propose that the (110) face provides reductive sites and that the (111) face provides oxidative sites. The results suggest that the crystal faces facilitate the separation of electrons and holes, resulting in improvement in photocatalytic activity.

Preparation and Luminescent Properties of YVO4:Eu3+ Nanofibers by Electrospinning

This paper describes a procedure based on electrospinning for generating europium-doped yttrium vanadate (YVO4:Eu3+) nanofibers with diameters ranging from 30 to 50 nm. The YVO4:Eu3+ nanofibers were obtained through calcining precursory nanofibers, which were prepared through the electrospinning method. Suitable electrospinning parameters, such as concentration of PVP in solution, spinneret tip-to-collector plate distance (TCD), and applied voltage between spinneret and collector plate, are used to obtain thinner and more uniform precursory nanofibers of YVO4:Eu3+, which is important for preparing smaller diameter pure YVO4:Eu3+ nanofibers. The luminescent properties of the YVO4:Eu3+ nanofibers including excitation and emission spectra and fluorescence lifetime were studied. The excitation spectrum shows a broad band extending from 200 to 350 nm, which corresponds to the strong vanadate absorption in YVO4:Eu3+. The emission spectrum is dominated by the red 5D0 --> 7F2 hypersensitive transition of Eu3+. The fluorescence lifetime of Eu3+ 5D0 --> 7F2 (619 nm) is determined to be 493 micros at room temperature, which is basically in accordance with that in the bulk (521 micros).

Interfacial and Bulk Behavior of Sodium Dodecyl Sulfate in Isopropanol−Water and in Isopropanol−Poly(vinylpyrrolidone)−Water Media

The surface activity of isopropanol (IP) and poly(vinylpyrrolidone) (PVP) at the air/water interface has been studied. The self-aggregation of sodium dodecyl sulfate (SDS) in IP-water as well as in IP-PVP-water media has been investigated using physical methods, viz., tensiometry, conductometry, calorimetry, and viscometry. The interaction of SDS with PVP in IP-water medium as well as its self-aggregation (or micellization) in the presence of PVP has been assessed. The results reveal a fair degree of surface activity of IP in aqueous medium, which is only moderate for PVP. The critical micellar concentration (CMC) of SDS passes through a minimum at (v/v) % IP = 6.62. SDS interacts with PVP, yielding a critical aggregation concentration (CAC) at a low [SDS], independent of IP content in the medium. At a higher [SDS], free micelle formation takes place in solution, which is lower in mixed solvent than in water and is independent of solvent composition by tensiometry, but not by conductometry and calorimetry. The viscosity of micelle-interacted PVP in solution takes a long time to stabilize, whereas, for non-interacting additives, such as NaCl and cetyltrimethylammonium bromide (CTAB), it is time independent.

Continuous synthesis of gold nanoparticles and nanoplates with controlled size and shape under UV irradiation

Gold nanoparticles and nanoplates were synthesized through a continuous method under UV irradiation in the presence of citric acid and poly(vinylpyrrolidone) (PVP) at room temperature. Morphologies of obtained gold nanoparticles were mainly determined by experimental parameters, i.e., the concentration of PVP and the flow rate of solution. The spherical gold nanoparticles were synthesized at a higher solution flow rate (6 mL/min). The particle sizes evidently decreased from more than 10 to 2 nm with increasing concentration of PVP in solution. When PVP was absent in solution, gold nanoplates with obtuse triangle, hexagon and round shapes were synthesized under a lower solution flow rate, such as 0.5 mL/min.

Supramolecular Structure of the LiPFN−PVP System: 19F NMR Studies

19F NMR measurements on lithium perfluorononanoate [LiPFN] in D2O and in solutions of D2O with poly(vinylpyrrolidone) [PVP] at different molecular weights have been carried out. A careful study of literature data and COSY maps allowed the full assignment of the 19F resonances as a function of concentration and composition of the systems. For the LiPFN/D2O system, analysis of the chemical shifts of the fluorine atoms bound to the different carbons of the LiPFN backbone reveals significant variations correlated to the LiPFN concentration. Such a finding has been explained in terms of the changes in the local dielectric constant caused by the surfactant self-aggregation process. The presence of PVP in solution strongly modifies the trend of the 19F chemical shifts observed in the binary LiPFN/D2O system. Such a feature, depending both on the position of the fluorine atoms along the surfactant backbone and on the LiPFN concentration, indicates the presence of strong polymer−surfactant interactions. The line w...

Synthesis of substituted poly(1‐vinylpyrene)s and investigation of their fluorescent properties

AbstractA series of functionalized linear poly(1‐vinylpyrene) (PVP) polymers bearing substituents such as NO2, CHO, NH2, Br, and CHC(CN)2, were prepared by chemical modification of PVP in solution. The degree of substitution in PVPCHC(CN)2 was varied from 40% to nearly 100% by control of the reaction conditions. The other polymers were partially functionalized. The UV‐visible and fluorescence spectroscopy of the polymers were studied in solution. The influence of solvent polarity, excitation energy, and degree of substitution on the fluorescence of the polymers were examined. © 1993 John Wiley & Sons, In

Hydrodynamic properties of poly(1‐vinyl‐2‐pyrrolidone) molecules in dilute solution

AbstractThe translational diffusion coefficient D0, the sedimentation coefficient S0, and the intrinsic viscosity [η] of samples and fractions of poly(1‐vinyl‐2‐pyrrolidone) were measured in a 0,1 M solution of sodium acetate in the molecular weight range 2 ≤ M · 10−3 ≤ 2200. For M > 4 · 104 the following relationships were obtained: [η] = 8,86 · 10−5 · M0,74, D0 = 2,42 · 10−4 · M−0,58, and S0 = 2,14 · 10−15 ·. M0,42. For M < 4 · 104 the corresponding relations are [η] = 5,0 · 10−4 · M0,56, D0 = 1,29 · 10‐4 · M−0,52 and S0 = 1,15 · 10−15 · M0,48. The hydrodynamic invariant is A0 = (3,2 ± 0,25) · 10−17 J · K−1 · mol−1/3 and the sedimentation parameter βs = (1,3 ± 0,17) · 107 mol−1/3. The temperature coefficient of the intrinsic viscosity is negative, viz. Δ ln[η]/ΔT = −6,3. 10M−3 K−1. The evaluation of the length of the Kuhn segment A and the hydrodynamic diameter d of chains representing the molecules of PVP in solution was conducted on the basis of the theory for the hydrodynamic properties of a wormlike necklace taking into account the excluded volume effects. The values of A agree with those obtained from the Burchard‐Stockmayer‐Fixman and Cowie‐Bywater equations, A = (2,1 ± 0,3) nm and d = (0,5 ± 0,13) nm.