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4 Biocomposites with Nanosilica, BSA and Sugars

4 Biocomposites with Nanosilica, BSA and Sugars

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Supramolecular Structures with Blood Plasma Proteins, Sugars and Nanosilica



319



Fig. 25.12 Interfacial energy as a function of composition of the HPF/Fm/Fb system on

transformation of fibrinogen into fibrin-monomer (Fm) and then fibrin-polymer (Fb)



basis of nanosilica [33], BSA, polyol (sorbitol, xylitol) or monosaccharides (fructose, glucose) in wide range of concentrations [39, 40] can stimulate activity [41]

and prolong lifetime of cells after their cryopreservation.

The motion characteristics of bovine reproductive cells (BRCs) – rotation frequency, forward motion velocity and corresponding kinetic energy, E – were

determined using laser Doppler spectroscopy [42]. These characteristics (Fig. 25.13)

are linked to the capability of BRCs for their typical functioning.

The ratio E/E0 > 1 (E0 is for BRCs at 8 × 108 cells/ml in the 2.9 wt% TSC buffer

solution) answers the stimulating effects of nanocomposite on BRCs, and E/E0 < 1

corresponds to the suppressing effects. The activity was determined for ten concentrations of BRCs in the 2 × 10−6 –0.6 wt% range. Obtained results (Fig. 25.13) show

that all studied composites (at certain concentrations) possess stimulating influence

on BRCs.

The dependences of E/E0 on lg C have a complex shape that indicates

the multifactor nature of the effects of bionanocomposites on the BRC



2.0



E/E0



Fig. 25.13 Dependence of

relative kinetic energy of

BRCs after cryopreservation

on concentration of

nanocomposite in

lactose/glycerol/vitelline

medium: A-300/saccharose

(curve 1, CSac = 0.8 mg/g),

A-300/BSA (2, CBSA =

570 mg/g) and

A-300/BSA/saccharose (3,

CBSA = 515 mg/g, CSac =

1.06 mg/g)



1



1.5



3

1.0



2



0.5



–3.0



–2.5



–2.0



–1.5



lgC



–1.0



–0.5



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V.V. Turov et al.



characteristics. Probably, the sign of the effects depends not only on concentration of solid nanoparticles (and their aggregation with BSA/sugars) but also on the

BRC/bionanocomposite interfaces state determined by concentration and type of

compounds adsorbed and desorbed there as well as by their conformation, rearrangement of supramolecular structures and desorption capability of sugars from

BSA-coated nanoparticles on interaction with BRCs.

The experiments showed that bionanocomposites based on nanosilica, BSA and

saccharose (at composite concentration of 0.0025 wt%) have the greatest positive

effects on the BRCs. In the presence of the bionanocomposite, the BRC lifetime is

longer by 2.5 h than that of the controls.

Since molecules of mono- and disaccharides poorly adsorb on the nanosilica surface one can assume that they adsorb to BSA molecules immobilised on silica. As

was shown above, sugars can displace large amounts of water bound to albumins due

to effective protein–sugar interactions. Especially great effects were observed on the

use of saccharose. One can assume that sugars bound in protein–silica nanocomposites and desorbed on interaction with cells are responsible for significant changes in

the stimulating effects on the BRCs.

Immobilisation of BSA on silica leads to an increase in the adsorption of saccharose by approximately 20% (Fig. 25.14). This difference is lower than could be

expected from the data discussed above. However, it should be noted that conformational changes in adsorbed protein molecules are more difficult than in dissolved

macromolecules alone. Additionally, BSA/nanosilica can form compacted hybrid

aggregates with reduced accessible surface area of both protein molecules and silica

surface for sugar molecules [24]. These effects can be responsible for the not-high

increase in the adsorption of saccharose on BSA/silica in comparison with silica

alone.

Two maxima on the E/E0 (lg C ) graph (Fig. 25.13) are observed at concentrations

of the solid phase of ∼10−2 and ∼10−1 wt%. Consequently, the BRC activation can

occur at different concentrations of different nanocomposites that can correspond

1.4



1

1.0



0.6

0.4

0.2

0.0

0.00



(a)



2



0.8



0.01



0.02



0.03



Ceq (mg/g)



Sacchrose ad(de)sorption (mg/g)



Sacchrose ad(de)sorption (mg/g)



1.2



1

1.2



0.8

0.6

0.4

0.2

0.0

0.00



0.04



(b)



2



1.0



0.01



0.02



0.03



0.04



Ceq (mg/ml)



Fig. 25.14 Adsorption (1) and desorption (2) isotherms of saccharose on surface of (a) nanosilica

and (b) BSA/nanosilica at CBSA = 515 mg/g



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Supramolecular Structures with Blood Plasma Proteins, Sugars and Nanosilica



321



to different mechanisms of the activation of the BRCs by desorbed sugars, BSA

immobilised and dissolved and unmodified and modified silica nanoparticles, as

well as by the adsorption of the products of the cell metabolism, etc.

Tendency to a decrease in the motion activity of the BRCs with increasing concentration of the dispersion phase can be caused by an increase in the viscosity of the

dispersion medium and by undesirable interactions of integral proteins with silica

aggregates resulting in agglutination of the cells [24, 33, 43]. Nanocomposites based

on nanosilica, serum albumin and sugars demonstrated the stimulating influence on

the vital activity of some other cells, e.g. red blood cells (RBCs) [44].

The effects of nanocomposites were studied at their concentration of

10−4 –1 wt% (aqueous suspensions of nanosilicas/BSA/sugar in 3.8 wt% trisodium

citrate) and CRBC = 6 × 107 cell/ml. It was found that the shape of RBCs changes

on interaction with unmodified and modified silicas from discocytes → echinocytes

→ spherocytes → deformed RBCs → shadow corpuscles depending on silica

concentration [44]. The interaction of RBCs with bionanocomposites (in contact

with nanosilica alone [44]) does not give shadow corpuscles (Fig. 25.15). The

transformation of discocytes to echinocytes begins from distortion to a convexoconvex contour of normal RBCs. Rough spicules appear first on the edge of the disk

and then on the whole RBC surface. The echinocyte spicules gradually become



Fig. 25.15 Histograms of the RBC shape distributions: discocytes (1), echinocytes (2), spherocytes (3) and deformed RBCs (4) on addition of A-300/BSA (585 mg/g) with (a) fructose (2 mg/g),

(b) glucose (2.25 mg/g) or (c) saccharose (1.25 mg/g) and (d) A-300/saccharose (0.8 mg/g) at total

concentration of composites between 0.0001 and 1 wt% (control is for RBCs at 6 × 107 cells/ml

in the 3.8 wt% TSC buffer solution)



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V.V. Turov et al.



thinner and more uniformly distributed on a cellular surface. Then cells become a

spherical shape. On the final transformation, cells lose a part of the spicules and the

transformation into the spherocyte shape becomes irreversible. A strong distortion

of the membrane (e.g. on interaction with silica nanoparticles alone) leads to loss of

its flexibility and resiliency. RBCs swell and increase in size in comparison with the

spherocyte that leads to membrane break. Eliminated haemoglobin can be detected.

However, the perforated cellular membrane remains as unique whole and forms the

so-called shadow corpuscle. Notice that haemolytic activity of 1 wt% suspension of

nanosilica A-300 corresponds to 100% in 20 min since only the shadow corpuscles

are observed [44]. In the presence of fructose and glucose in nanocomposites, an

increase in the concentration of discocytes is observed in comparison with the

control (Fig. 25.15). However, interaction of RBCs with A-300/BSA/saccharose

(Fig. 25.15c) or A-300/saccharose (Fig. 25.15d) leads to more negative effects since

the number of normal discocytes decreases but the number of spherocytes increases.

Consequently, composites with nanosilica–protein–monosugar can better stabilise

the cell membrane or retard their destruction at the threshold concentrations of solid

phase in comparison with nanosilica–protein–saccharose. Probably, the differences

in the influence of di- and monosugars (as components of nanocomposites) on

RBC depend on their chemical structure, interaction with BSA, changes in the

free energy of solvation on adsorption/desorption and bonding to RBCs, as well

as on their complement-fixing ability with respect to terminal carbohydrates of

oligosaccharide functionalities of the receptor molecules of the supracellular matrix

of RBCs. For instance, the free energy of solvation is Gsol = −541 (glucose),

−352 (fructose) and −344 (saccharose) J/g (calculated using IEFPCM/B3LYP/631G(d,p)//HF/6-31G(d,p) method). Consequently, the adsorption of saccharose on

silica, albumin or albumin/silica from the aqueous solution could be better and the

effects on bound water should be stronger than that for monosugars.



25.5 Conclusion

The low-temperature 1 H NMR spectroscopy used to determine the interfacial

energy of biomacromolecules and related bionanocomposites has some advantages

in comparison with other methods measuring similar characteristics. In contrast

to calorimetric method determining the adhesion energy it does not require long

time to reach equilibrium and it is more sensitive at low concentrations of solid

phase. Additionally, it allows the determination of the radial dependences of adhesive forces in aqueous media, size distributions of cavities (pores, voids) filled by

unfrozen bound water in any materials and the thickness of bound water layers up

to 10 nm or larger that is impossible by using other methods. The concentration

dependences of interfacial energy can be used to determine the energy of intermolecular interaction of protein molecules (energy of self-association) and the energy of

swelling or destroying of protein gels, gel-like structures formed in the suspensions

of nanoparticles or supramolecular systems. For aqueous solutions of biopolymers,



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Supramolecular Structures with Blood Plasma Proteins, Sugars and Nanosilica



323



solid nanoparticles and low molecular organics (sugars), the dependence of interfacial energy on concentrations of dispersion components is quite informative since it

is possible to trace the processes of adsorption, gel formation, coagulation, etc. The

obtained results for supramolecular structures with nanosilica, proteins and monoand disugars allow us to explain certain features of the influence of the bionanocomposites on living cells, in particular the effects of saccharose on the activity of BRCs

and transformations of RBCs from normal discocytes to echinocytes, spherocytes to

shadow corpuscles on interaction with bionanocomposites.

Acknowledgement This research was supported by Science & Technology Center in Ukraine

(project No 3832) and National Academy of Sciences of Ukraine (Complex Program of

Fundamental Investigations “Nanostructural Systems, Nanomaterials, and Nanotechnology”).



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Part V



Nanotubes and Carbon Nanostructured

Materials



This part is devoted to studies of new types of functional materials made on the

base of silica and carbon nanotubes, diamond-like carbon films, highly dispersed

graphites and diamonds, and porous diamond compacts.

Nanotubes are one of the most prospective nanomaterials for various applications due to possession of unique electrical, mechanical, thermophysical, adsorptive

properties, etc., which depend on their chemical composition and structural features.

Special attention in literature is paid to obtaining filled nanotubes, in particular,

filled by metals. Studies of physical properties of such systems have a fundamental scientific importance. So, conductivity of electroconductive materials of few

nanometers in diameter becomes close to unidimensional, thus providing a possibility for arising quantum effects, specific magnetic and emitting properties. Therefore

development of design and assembly methods for nanotubes containing metal in

their inner cavity is of great importance for improvement of existing and introduction of new scientific approaches for creation of the elemental base, nano- and

molecular electronic devices and equipment.

The use of carbon nanotubes for the modification of polymeric matrixes not only

provides increased electric, structural–mechanical, and thermophysical characteristics, but also improves their biocompatibility. Thus, such composites are prospective

ones for producing chemical-resistant medical implants with improved strength and

weight properties.

Composite materials based on polymers and various forms of graphite, modified

by oxide clusters, are used for creation of gas-sensor elements. Their adsorption–

desorption rate, selectivity to influence of various molecules, threshold of percolation, and the value of electric resistance can be controlled in a certain range via

changing the type of polymer, graphite, and modifier and chemical composition of a

composite. Gas-sensor elements are characterized by operation at room temperature,

stability of characteristics, acceptable time of adsorption response, and a possibility

of multiple use.

The features of diamond-like carbon films, highly dispersed diamonds, and

porous diamond compacts were analyzed and compared with properties of certain nitride, carbide, oxide, graphite-like, and some metallic structures from the

viewpoint of their usage as technical and biocompatible materials and coatings.



328



Part V Nanotubes and Carbon Nanostructured Materials



Combining experimental methods of scientific investigations allows high reliability forecasting of strength, tribology, adsorption characteristics, and corrosion

resistance of materials upon their contact with biological environment.



Chapter 26



Design and Assembly of High-Aspect-Ratio

Silica-Encapsulated Nanostructures

for Nanoelectronics Applications

N.I. Kovtyukhova



Abstract This chapter summarizes our progress in design and assembly of new

metal nanowire-based insulated interconnects and coaxially gated in-wire thin film

transistors with the electrical characteristics closely approaching those of established large-scale planar thin film devices. Our approach relies on combining

templated synthesis of nanostructures with wet successive adsorption techniques

and electroplating. The strong advantages of this approach are (i) a possibility to

easily incorporate various electronic materials into a single nanostructure, (ii) control of the device geometric parameters with sub-nanometer precision, and (iii) using

low-energy-cost and environmentally friendly synthetic methods.



26.1 Introduction

A dramatic increase in research activity on nanoscale high-aspect-ratio inorganic

structures has been motivated by their unique electronic, optical, catalytic, and

mechanical properties determined by their shape, size, and, in many cases, singlecrystal morphology. Among those, nanowires and nanotubes have received major

attention as potential components of electronic circuits [1–5], photovoltaic cells

[6–8], chemical and biological sensors [9, 10], battery anodes [11] and, very

recently, nanomotors [12–14] and nanolocomotives [15, 16].

The chemical assembly of nanowires is now considered a potentially viable

alternative to the conventional lithographic fabrication of nanoscale circuits, which

is increasingly approaching physical and economic limits [1, 17, 18]. As highaspect-ratio structures, nanowires and nanotubes appear to be ideal building blocks

in chemically assembled electronic and optoelectronic nanotechnology. Their



N.I. Kovtyukhova (B)

Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA;

O.O. Chuiko Institute of Surface Chemistry of the National Academy of Sciences of Ukraine,

General Naumov St. 17, Kyiv 03164, Ukraine,

e-mail: nina@chem.psu.edu



A.P. Shpak, P.P. Gorbyk (eds.), Nanomaterials and Supramolecular Structures,

DOI 10.1007/978-90-481-2309-4_26, C Springer Science+Business Media B.V. 2009



329



330



N.I. Kovtyukhova



nanometer-size diameters and micron-size length allow for the fabrication of compact arrays of well-aligned parallel devices. Deposition of such an array on a

lithographically pre-patterned substrate can be used to prepare planar ultradense

electronic circuits composed of individually addressable device elements [19, 20].

Impressively, ∼1011 cross-point junctions can be fabricated on an area of 1 cm2

[20]. Chemically grown arrays of vertically aligned parallel wires and tubes have

been explored as 3D electron-harvesting and transport structures in solar cells [8],

field emission displays [21], and multiple sensor arrays [9].

While most of this research has involved semiconductor nanowires and singlewalled carbon nanotubes (SWNTs), functionalized metal nanowires have also been

actively studied for this application [5, 20, 22–26]. Metal nanowires provide reliable control over physical dimensions, surface chemistry, and transport properties

and can be easily prepared [27] and functionalized by low-temperature techniques

[5, 22–26].

Our approach to electronically functional metal nanowires relies upon wet chemical assembly of established ultrathin film devices [6, 28] and their shaping into

nanowire-based structures. This can be achieved by performing chemical and electrochemical synthesis inside the cylindrical pores of a template membrane. By

exploiting surface chemistry of the metal wire and pore walls, the electroactive films

can be deposited between two metal wire segments and/or around the wire body.

The precise control over the film thickness is realized using successive adsorption

techniques, such as layer-by-layer [23] or surface sol–gel deposition (SSG) [24, 25,

29, 30].

An important advantage of this strategy is a possibility to easily combine components with different electronic and chemical properties (such as metals, semiconductors, polymers, short SWNTs, and insulating oxides) in a single-wire structure.

Multicomponent “all-in-wire” diodes [23, 26], transistors [25], photodetectors [31],

and sensors [32] can be prepared in this way.

Additionally, the approach described here fulfills the requirements of future

electronic applications particularly well because it (i) provides technologically simple preparation of a large number (∼109 per membrane) of relatively uniform

nanowire devices with precise control over their geometric parameters and (ii) uses

low-energy-cost and environmental friendly “green” synthetic methods.

Highly conductive metals offer some special advantages, particularly as

low-resistance interconnects in high-speed circuits. A further reduction in RC

(resistance–capacitance) and LC (inductance−capacitance) time constants for

nanoscale circuits can be expected if low dielectric constant (low-k) materials can

be introduced as insulating spacers between metallic nanowires [33]. For example,

copper/low-k interconnect is currently a growing choice for high-performance chips

[34]. Silicon dioxide is the relatively low-k dielectric material that is most widely

used in CMOS integrated-circuit technology. Incorporation of SiO2 into metal

wire-based device structures requires new techniques for making ultrathin silica

nanotubes of high quality with the thickness control at the sub-nanometer level.

This chapter summarizes our progress in design and assembly of ultrathin silica nanotubes, SiO2 -insulated metal nanowire interconnects, and coaxially gated

in-wire thin film transistors with the electrical characteristics closely approaching



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