TY  - CHAP
A1  - Xiong, Xin
A1  - Hossfeld, Susanne
A1  - Margutti, Simona
A1  - Krastev, Rumen
ED  - Scholz, Martin
T1  - Polyelectrolyte multilayers as functional coatings for controlled biomolecular interactions
T2  - Biofunctional surface engineering
N2  - This review gives a short overview of the physical processes involved in the formation of the polyelectrolyte multilayers (PEMs) and their destruction. These two processes are vital for the formation of PEMs with desired physical and chemical structures, and for loading them with active substances and their spatial controlled release. It includes a survey of the physical and chemical properties that are key points for controlling film nanostructure in relation to biological processes and different possibilities for controlling cell behavior by means of film composition, bioactivity, mechanical properties, and three-dimensional organization.
Y1  - 2015
SN  - 978-981-4411-61-5
SP  - 47
EP  - 69
PB  - Pan Stanford Publishing
CY  - Singapore
ER  - 
TY  - JOUR
A1  - Andreeva, Tonya
A1  - Hartmann, Hanna
A1  - Taneva, Stefka
A1  - Krastev, Rumen
T1  - Regulation of the growth, morphology, mechanical properties and biocompatibility of natural polysaccharide-based multilayers by Hofmeister anions
JF  - Journal of materials chemistry. - B. Materials for biology and medicine
N2  - Herein the optimization of the physicochemical properties and surface biocompatibility of polyelectrolyte multilayers of the natural, biocompatible and biodegradable, linear polysaccharides hyaluronan and chitosan by Hofmeister anions was systematically investigated. We demonstrated that there is an interconnection between the bulk and surface properties of HA/Chi multilayers both varying in accordance with the arrangement of the anions in the Hofmeister series. Kosmotropic anions increased the hydration, thickness, micro- and macro-roughness, and hydrophilicity and improved the biocompatibility of the films by reduction (2 orders of magnitude) of the films stiffness and complete anti-thrombogenicity.
Y1  - 2017
U6  - http://dx.doi.org/10.1039/C6TB01638C
SN  - 1552-4973
VL  - 4
IS  - 44
SP  - 7092
EP  - 7100
PB  - The Royal Society of Chemistry
CY  - Cambridge
ER  - 
TY  - JOUR
A1  - Georgiev, Georgi
A1  - Yokoi, Norihiko
A1  - Ivanova, Slavyana
A1  - Tonchev, Vesselin
A1  - Nencheva, Yana
A1  - Krastev, Rumen
T1  - Surface relaxations as a tool to distinguish the dynamic interfacial properties of films formed by normal and diseased meibomian lipids
JF  - Soft matter
N2  - The surface properties of human meibomian lipids (MGS), the major constituent of the tear film (TF) lipid layer, are of key importance for TF stability. The dynamic interfacial properties of films by MGS from normal eyes (nMGS) and eyes with meibomian gland dysfunction (dMGS) were studied using a Langmuir surface balance. The behavior of the samples during dynamic area changes was evaluated by surface pressure–area isotherms and isocycles. The surface dilatational rheology of the films was examined in the frequency range 10−5 to 1 Hz by the stress-relaxation method. A significant difference was found, with dMGS showing slow viscosity-dominated relaxation at 10−4 to 10−3 Hz, whereas nMGS remained predominantly elastic over the whole range. A Cole–Cole plot revealed two characteristic processes contributing to the relaxation, fast (on the scale of characteristic time τ < 5 s) and slow (τ > 100 s), the latter prevailing in dMGS films. Brewster angle microscopy revealed better spreading of nMGS at the air–water interface, whereas dMGS layers were non-uniform and patchy. The distinctions in the interfacial properties of the films in vitro correlated with the accelerated degradation of meibum layer pattern at the air–tear interface and with the decreased stability of TF in vivo. These results, and also recent findings on the modest capability of meibum to suppress the evaporation of the aqueous subphase, suggest the need for a re-evaluation of the role of MGS. The probable key function of meibomian lipids might be to form viscoelastic films capable of opposing dilation of the air–tear interface. The impact of temperature on the meibum surface properties is discussed in terms of its possible effect on the normal structure of the film.
Y1  - 2015
U6  - http://dx.doi.org/10.1039/C4SM00758A
SN  - 1744-683X
VL  - 10
IS  - 30
SP  - 5579
EP  - 5588
PB  - Royal Society of Chemistry
CY  - London
ER  -