Papers by John Tsibouklis
Langmuir : the ACS journal of surfaces and colloids, Mar 20, 2018
Toward engineering approaches that are designed to optimize the particle size, morphology, and mu... more Toward engineering approaches that are designed to optimize the particle size, morphology, and mucoadhesion behavior of the particulate component of inhaler formulations, this paper presents the preparation, physicochemical characterization, and preliminary in vitro evaluation of multicomponent polymer-lipid systems that are based on "spray-drying engineered" α-lactose monohydrate microparticles. The formulations combine an active (budesonide) with a lung surfactant (dipalmitoylphosphatidylcholine) and with materials that are known for their desirable effects on morphology (polyvinyl alcohol), aerosolization (l-leucine), and mucoadhesion (chitosan). The effect of the composition of formulations on the morphology, distribution, and in vitro mucoadhesion profiles is presented along with "Calu-3 cell monolayers" data that indicate good cytocompatibility and also with simulated-lung-fluid data that are consistent with the therapeutically useful release of budesonide.
ChemInform
ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance t... more ABSTRACT ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Journal of drug targeting, Jan 19, 2016
Effective therapy lies in achieving a therapeutic amount of drug to the proper site in the body a... more Effective therapy lies in achieving a therapeutic amount of drug to the proper site in the body and then maintaining the desired drug concentration for a sufficient time interval to be clinically effective for treatment. The blood-brain barrier (BBB) hinders most drugs from entering the central nervous system (CNS) from the blood stream, leading to the difficulty of delivering drugs to the brain via the circulatory system for the treatment, diagnosis and prevention of brain diseases. Several brain drug delivery approaches have been developed, such as intracerebral and intracerebroventricular administration, intranasal delivery and blood-to-brain delivery, as a result of transient BBB disruption induced by biological, chemical or physical stimuli such as zonula occludens toxin, mannitol, magnetic heating and ultrasound, but these approaches showed disadvantages of being dangerous, high cost and unsuitability for most brain diseases and drugs. The strategy of vector-mediated blood-to-...
J Pharm Sci, 2003
Polymeric microparticles were fabricated from Carbopol, polycarbophil, chitosan, or Gantrez using... more Polymeric microparticles were fabricated from Carbopol, polycarbophil, chitosan, or Gantrez using a ''water-in-oil emulsification'' solvent evaporation method. Mean particle sizes, as determined by laser diffraction, were in the range 23-38 mm. Electron microscopy revealed that all microparticles were spherical and of smooth surface morphology. In pH 7.0 phosphate buffered saline, the microspheres exhibited significantly increased swelling ratios and longer half-times of swelling than the corresponding powdered polymers. The relative merits of the potential usefulness of these microspheres as formulation tools for the enhanced retention of a therapeutic entity within the oral mucosa were evaluated by in vitro mucoadhesion tests. Tensile tests showed that all microspheres under consideration were capable of adhering to porcine esophageal mucosa, with particles prepared from the poly(acrylic acid)s exhibiting greater mucoadhesive strength than those constructed from chitosan or Gantrez. However, in elution experiments involving a challenge with artificial saliva, particles of chitosan or Gantrez were retained onto mucosal tissue for longer time periods than those assembled from the poly(acrylic acid)s.
Ferroelectrics, 1993
Thin pyroelectric composite films have been fabricated in which both phases are electroactive. Tr... more Thin pyroelectric composite films have been fabricated in which both phases are electroactive. Triglycine sulphate crystals, grown by freezing an aqueous solution at various rates and freeze-drying the resultant solid mass, were mixed (10% w/w) with a solution of 70:30 vinylidene fluoride:trifluoroethylene copolymer in butanone and films were produced by spin-coating. The best material possessed a pyroelectric coefficient of (60 ± 2) μCm-2 K-1 and a figure of merit (pyroelectric coefficient/✓ (relative permittivity × dielectric loss)) of 150 μCm-2 K-1, some 18% and 35% larger, respectively, than the corresponding values for the copolymer alone.
Synthetic Communications, Dec 1, 1998
A one-pot reaction which combines the Cadiot-Chodkiewicz coupling reaction with the Gabriel synth... more A one-pot reaction which combines the Cadiot-Chodkiewicz coupling reaction with the Gabriel synthesis of primary amines is evaluated as a means for the synthesis of unsymmetrically disubstituted aminodiacetylenes of the type CH2-(CH2)n-C≡C-C≡C-CH2-NH2 (n=2,3,4,5).
Pharmaceutical Research, 2016
PURPOSE: Tumor cell heterogeneity and microenvironment represent major hindering factors in the c... more PURPOSE: Tumor cell heterogeneity and microenvironment represent major hindering factors in the clinical setting toward achieving the desired selectivity and specificity to malignant tissues for molecularly targeted cancer therapeutics. In this study, the cellular and molecular evaluation of several delocalized lipophilic cation (DLC)-functionalized carborane compounds as innovative anticancer agents is presented. METHODS: The anticancer potential assessment of the DLC-carboranes was performed in established normal (MRC-5, Vero), cancer (U-87 MG, HSC-3) and primary glioblastoma cancer stem (EGFR pos , EGFR neg) cultures. Moreover, the molecular mechanism of action underlying their pharmacological response is also analyzed. RESULTS: The pharmacological anticancer profile of DLC-functionalized carboranes is characterized by: a) a marked in vitro selectivity, due to lower concentration range needed (ca. 10 fold) to exert their cell growth-arrest effect on U-87 MG and HSC-3, as compared with that on MRC-5, Vero; b) a similar selective growth inhibition behavior towards EGFR pos and EGFR neg cultures (>10 fold difference in potency) without, however, the activation of apoptosis in cultures; c) notably, in marked contrast to cancer cells, normal cells are capable of recapitulating their full proliferation potential following exposure to DLC-carboranes; and, d) such pharmacological effects of DLC-carboranes has been unveiled to be elicited at the molecular level through activation of the p53/p21 axis. CONCLUSIONS: Overall, the data presented in this work indicates the potential of the DLC-functionalized carboranes to act as new selective anticancer therapeutics that 3 may be used autonomously or in therapies involving radiation with thermal neutrons. Importantly, such bifunctional capacity may be beneficial in cancer therapy.
Biofouling, 2000
ABSTRACT Melt‐coated films of poly(fluoroalkylacrylate)s and poly(fluoroalkylmethacrylate)s have ... more ABSTRACT Melt‐coated films of poly(fluoroalkylacrylate)s and poly(fluoroalkylmethacrylate)s have been exposed respectively to bacterial cultures (Pseudomonas spp., Alteromonas sp. NCIMB 1534 and Desulphovibrio alaskensis NCIMB 13491), Enteromorpha zoospores and cyprid larvae of Balanus amphitrite Darwin. In all experiments, settlement and development was considerably less on the films than on controls of glass, poly‐(methylmethacrylate), poly(tetrafluoroethene) (ptfe) and polyester/glassf ibre composite. The settled bacteria were also much more weakly attached to the fluoropo‐lymer films than to the controls. Enteromorpha zoospores tended to settle at surface faults/cracks and also showed some sensitivity to the fluorine content of the materials. Cyprids did not settle on ptfe and could find only occasional sights for attachment on the films. Although the fluoropolymers show promise as fouling‐resistant coatings, improvements in film quality are required.
Synthet Metal, 1995
The conductivity of single crystals of bis-p-toluenesulphonate polydiacetylene (PDA-TS) was studi... more The conductivity of single crystals of bis-p-toluenesulphonate polydiacetylene (PDA-TS) was studied using the pulse-radiolysis time resolved microwave conductivity (PR-TRMC) technique. This technique allows us to probe the charge carrier transport along the individual polymer chains. An anisotropy ratio of 220 was found in favour of charge transport in the direction of the conjugated polymer backbone as compared to the transverse direction. A lower limit of low3 m*Ns is found for the charge carrier mobilities.
International Journal of Pharmaceutics, 2015
There is a requirement for the development of oral dosage forms that are adhesive and allow exten... more There is a requirement for the development of oral dosage forms that are adhesive and allow extended oesophageal residence time for localised therapies, or are non-adhesive for ease of swallowing. This study provides an initial assessment of the in vitro oesophageal retention characteristics of several widely utilised pharmaceutical coating materials. To this end, a previously described apparatus has been used to measure the force required to pull a coated disc-shaped model tablet across a section of excised oesophageal tissue. Of the materials tested, the well-studied mucoadhesive polymer sodium alginate was found to be associated with significant oesophageal adhesion properties that was capable of 'self-repairing'. Hydroxypropylmethylcellulose exhibited less pronounced bioadhesive behaviour and blending this with plasticiser or with low molecular weight polymers and surfactants did not significantly affect this. Low molecular weight water soluble polymers, were found to behave similarly to the uncoated glass control disc. Polysorbates exhibited bioadhesion behaviour that was majorly influenced by the nature of the surfactant. The insoluble polymer ethylcellulose, and the relatively lipophilic surfactant sorbitan monooleate were seen to move more readily than the uncoated disc, suggesting that these may have a role as 'easy-to-swallow' coatings.
Australian Journal of Chemistry
Uploads
Papers by John Tsibouklis