1: Magnetic Particles: Preparation, Properties and Applications: M. Ozaki. 2: Maghemite (gamma-Fe2O3): A Versatile Magnetic Colloidal Material C.J. Serna, M.P. Morales. 3: Dynamics of Adsorption and Oxidation of Organic Molecules on Illuminated Titanium Dioxide Particles Immersed in Water M.A. Blesa, R.J. Candal, S.A. Bilmes. 4: Colloidal Aggregation in Two-Dimensions A. Moncho-Jorda, F. Martinez-Lopez, M.A. Cabrerizo-Vilchez, R. Hidalgo Alvarez, M. Quesada-PMerez. 5: Kinetics of Particle and Protein Adsorption Z. Adamczyk.

Surface and Colloid Science

https://cyberleninka.org/article/n/398815.pdf

Analytical techniques in pharmaceutical analysis: A review

The aggregation of proteins is of fundamental relevance in a number of daily phenomena, as important and diverse as blood coagulation, medical diseases, or cooking an egg in the kitchen. Colloidal food systems, in particular, are examples that have great significance for protein aggregation, not only for their importance and implications, which touches on everyday life, but also because they allow the limits of the colloidal science analogy to be tested in a much broader window of conditions, such as pH, ionic strength, concentration and temperature. Thus, studying the aggregation and self-assembly of proteins in foods challenges our understanding of these complex systems from both the molecular and statistical physics perspectives. Last but not least, food offers a unique playground to study the aggregation of proteins in three, two and one dimensions, that is to say, in the bulk, at air/water and oil/water interfaces and in protein fibrillation phenomena. In this review we will tackle this very ambitious task in order to discuss the current understanding of protein aggregation in the framework of foods, which is possibly one of the broadest contexts, yet is of tremendous daily relevance.

http://iopscience.iop.org/article/10.1088/0034-4885/76/4/046601/pdf

The self-assembly, aggregation and phase transitions of food protein systems in one, two and three dimensions

Bone morphogenetic peptides (BMPs), a family of cytokines critical to normal development, were recently implicated in the pathogenesis of familial pulmonary arterial hypertension. The type-II receptor (BMPRII) is required for recognition of all BMPs, and targeted deletion of BMPRII in mice results in fetal lethality before gastrulation. To overcome this limitation and study the role of BMP signaling in postnatal vascular disease, we constructed a smooth muscle–specific transgenic mouse expressing a dominant-negative BMPRII under control of the tetracycline gene switch (SM22-tet-BMPRIIdelx4+ mice). When the mutation was activated after birth, mice developed increased pulmonary artery pressure, RV/LV+S ratio, and pulmonary arterial muscularization with no increase in systemic arterial pressure. Studies with SM22-tet-BMPRIIdelx4+ mice support the hypothesis that loss of BMPRII signaling in smooth muscle is sufficient to produce the pulmonary hypertensive phenotype.

Pulmonary Hypertension in Transgenic Mice Expressing a Dominant-Negative BMPRII Gene in Smooth Muscle

Macroscopic characterizations of hydrophobicity (e.g., contact angle measurements) do not extend to the surfaces of proteins and nanoparticles. Molecular measures of hydrophobicity of such surfaces need to account for the behavior of hydration water. Theory and state-of-the-art simulations suggest that water density fluctuations provide such a measure; fluctuations are enhanced near hydrophobic surfaces and quenched with increasing surface hydrophilicity. Fluctuations affect conformational equilibria and dynamics of molecules at interfaces. Enhanced fluctuations are reflected in enhanced cavity formation, more favorable binding of hydrophobic solutes, increased compressibility of hydration water, and enhanced water-water correlations at hydrophobic surfaces. These density fluctuation–based measures can be used to develop practical methods to map the hydrophobicity/philicity of heterogeneous surfaces including those of proteins. They highlight that the hydrophobicity of a group is context dependent and is ...

Hydrophobicity of Proteins and Interfaces: Insights from Density Fluctuations

We have determined the structural conformations of human lactoferrin adsorbed at the air/water interface by neutron reflectivity (NR) and its solution structure by small angle neutron scattering (SANS). The neutron reflectivity measurements revealed a strong structural unfolding of the molecule when adsorbed at the interface from a pH 7 phosphate buffer solution (PBS with a total ionic strength at 4.5 mM) over a wide concentration range. Two distinct regions, a top dense layer of 15−20 A on the air side and a bottom diffuse layer of some 50 A into the aqueous subphase, characterized the unfolded interfacial layer. At a concentration around 1 g dm-3, close to the physiological concentration of lactoferrin in biological fluids, the adsorbed amount was 5.5 × 10-8 mol m-2 in the absence of NaCl, but the addition of 0.3 M NaCl reduced protein adsorption to 3.5 × 10-8 mol m-2. Although the polypeptide distributions at the interface remained similar, quantitative analysis showed that the addition of NaCl reduced...

Surface-induced unfolding of human lactoferrin

The natural tear fluid forms a thin covering over the surface of the cornea and conjunctiva and serves a number of vital functions.i It produces an optically smooth surface, provides a barrier to microorganism and particulate debris, delivers nutrients to the underlying tissue, and lubricates the movements of the eyelid. It is a dynamic structure with continual turnover of its constituents, and the layer is regenerated after each blink. Failure of the tear film leads to a number of clinical pathological conditions known collectively as Dry Eye Syndrome. The structure and composition of the tear film have been described in some detail,ii,iii and its importance greatly debated because of its relevance for the experimental and therapeutic management of dry eye. However, physiological function is dependent on the physical properties of the components, an understanding of which is emerging more slowly. Consequently, the development of therapeutic stratagems for Dry Eye Syndrome and, in particular, of synthetic tear substitutes remains quite pragmatic.

Interface properties of simplified tear-like fluids in relation to lipid and aqueous layers composition.

Coadsorption of human milk lactoferrin into the dipalmitoylglycerolphosphatidylcholine phospholipid monolayer spread at the air/water interface

Dexamethasone transport across ocular epithelium was evaluated by means of permeability studies on a series of ester prodrugs with the aim of identifying the most promising candidates for the treatment of the ocular surface. Organotypic conjunctival bovine epithelial cell cultures were assumed representative of an average ocular epithelium and used to describe the mechanism of permeation. Permeability coefficients were also determined in excised rabbit corneas set up and in vivo pharmacokinetic experiments. All dexamethasone esters permeated through the transcellular route and their permeability coefficient rose with the increase of the molecules lipophilicity until a maximum was reached in correspondence of dexamethasone butyrate (Log P = 3.95). It was found that esters hydrolysis occurring in various extent along the transport process, affected the overall permeability rate. There was evidence that the permeation process can be confined at the ocular epithelium layer if the ester is highly hydrophobic and not susceptible of fast hydrolysis.

Ocular Permeability Screening of Dexamethasone Esters Through Combined Cellular and Tissue Systems

Purpose. To determine the concentration of netilmicin in tears after eye drop administration. Methods. A clinical study was carried out on 32 healthy volunteers. Subjects were divided into four groups and underwent tear collection at 5, 10, 20, and 60-minutes after drug administration, respectively. Tear samples were collected through capillary suction from the inferior conjunctival "cul-de-sac" and analyzed by high-pressure liquid chromatography (HPLC). Results. Netilmicin concentration in tears decreased after a first order kinetics, a best-fit curve was drawn and the minimum inhibitory concentration (MIC 9 0 ) intersection for the most common ocular pathogens was calculated. Conclusions. The extrapolation of the curve shows that the concentration of netilmicin on the ocular surface can be effective against microorganisms more than 120 minutes after eye drop instillation.

Fausto Miano

Papers

Surface-induced unfolding of human lactoferrin

Interface properties of simplified tear-like fluids in relation to lipid and aqueous layers composition.

Coadsorption of human milk lactoferrin into the dipalmitoylglycerolphosphatidylcholine phospholipid monolayer spread at the air/water interface

Ocular Permeability Screening of Dexamethasone Esters Through Combined Cellular and Tissue Systems

Residence time of netilmicin in tears.