| Current
Nanoscience
ISSN: 1573-4137
Current Nanoscience
Volume 2, Number 3, August 2006
Contents
Trends in Bio-Hybrid Nanostructured Materials
Guest Editors: Eduardo Ruiz-Hitzky and Margarita Darder
Editorial Pp. 153
Nanostructured Biomaterials for Regenerative Medicine
Pp. 155-177
Vinoy Thomas, Derrick R. Dean and Yogesh K. Vohra
[Abstract]
Nanostructured Hybrid Materials for Bone Tissue Regeneration
Pp. 179-189
María Vallet-Regí and Daniel Arcos
[Abstract]
Properties of Hydroxyapatite – Hyaluronic Acid
Nano-Composite Sol and its Interaction with Natural Bones
and Collagen Fibers Pp. 191-196
Yuichi Ishikawa, Jun Komotori and Mamoru Senna
[Abstract]
Recent Progresses in Bio-Inorganic Nanohybrids
Pp. 197-210
Katsuhiko Ariga, Ajayan Vinu and Masahiko Miyahara
[Abstract]
Enzymes and Bio-Molecular Assemblies in Nano-Spaces
of Mesoporous Silica Pp. 211-218
Yoshiaki Fukushima, Tsutomu Kajino and Tetsuji Itoh
[Abstract]
Sol-Gel Biopolymer/Silica Nanocomposites in Biotechnology
Pp. 219-230
Thibaud Coradin, Joachim Allouche, Michel Boissière
and Jacques Livage
[Abstract]
Bio-Nanohybrids Based on Layered Inorganic Solids:
Gelatin Nanocomposites Pp. 231-241
Margarita Darder, Ana Isabel Ruiz, Pilar Aranda, Henri
Van Damme and Eduardo Ruiz-Hitzky
[Abstract]
Nanopore Membranes for Biomaterials Synthesis, Biosensing
and Bioseparations Pp. 243-255
Lane A. Baker, Youngseon Choi and Charles R. Martin
[Abstract]
Nucleic Acids and Their Analogs as Nanomaterials
for Biosensor Development Pp. 257-273
Carlos Briones and José Ángel Martín-Gago
[Abstract]
Bio-Nanohybrids Based on Layered Double Hydroxide
Pp. 275-281
Jin-Ho Choy, Man Park and Jae-Min Oh
[Abstract]
Nanohybrid Enzymes - Layered Double Hydroxides: Potential
Applications Pp. 283-294
Claude Forano, Stéphanie Vial and Christine Mousty
[Abstract]
Abstracts
[Back to top]
Editorial
Trends in Bio-Hybrid Nanostructured Materials
Bio-nanohybrid materials constitute an emerging interdisciplinary
field in the frontier between Life Sciences, Material Sciences
and Nanotechnology. Since the last few years, special attention
is being devoted to bio-nanohybrids due to their incidence
in significant areas from regenerative medicine to new materials
showing improved functional and structural properties.
This issue of CNANO introduces some selected works showing
recent research focused on the synthesis and properties of
bio hybrid materials, which are based on the assembly at the
nanometric scale of compounds derived from natural sources
with different inorganic solids. Among these nanostructured
materials, the structural and functional bio-hybrids resulting
from the combination of natural polymers, such as polysaccharides,
polyesters, RNA and DNA, polypeptides, fibrous and globular
proteins and enzymes, with inorganic substrates, such as silica
and phyllosilicates, layered double hydroxides (LDHs), phosphates
and metal oxides, are significant examples illustrating new
insights in this multidisciplinary area.
Nowadays, there is an increasing interest in the preparation
of bio-inspired or biomimetic materials following the examples
found in Nature, developing bio-nanohybrids of enhanced mechanical
resistance mimicking the exceptional features of native materials.
Illustrating these features, studies on bio-nanohybrids that
mimic the hierarchical structural bone organization are presented
in this Issue by Senna’s and Vallet’s Groups.
These authors report about the bio-nanohybrids based on the
assembling of nanosized hydroxyapatite and other inorganic
substrates with collagen and other proteins as key materials
for artificial bones. In this context, the review by Vohra
and co-workers highlights the preparation of nanostructured
biomaterials for tissue engineering. Recent advances on fabrication
of nanofibrous matrices of biopolymers for tissue engineering
scaffold applications attained by the Vohra’s Group
are reported and discussed by these authors. Despite the great
number of publications within this topic, this key contribution
signals that this type of bio-nanohybrids can still be considered
in its infancy regarding their possibilities for application
in regenerative medicine.
Bio-nanohybrids derived from the assembly of silica and silicate
particles with biomolecules constitute one of the major topics
in relation with the scope of this Special Issue. In this
context, Ariga and co-workers introduce an overview on organicinorganic
hybrids derived from the immobilization of biomolecules on
nanosized inorganic substrates. These authors have developed
a new concept of multicellular mimicking systems named cerasomes,
which are based on hybrid vesicles. Bioencapsulation of enzymes
and other biological molecules in mesoporous silica gives
bio-nanohybrids in which their stability is increased allowing
future applications as catalysts, membranes or energy conversion
devices, as reviewed by Fukushima and co-workers at the Toyota
Central R&D Laboratory. Combination at the molecular level
of biopolymers such as polysaccharides and structural proteins
with inorganic silica and other inorganic substrates leads
to an emerging research field in the so-called bio-nanocomposite
materials. In this way, the contribution by Livage’s
Group refers to sol-gel processes giving silica based bio-nanocomposites,
which show resemblance with native biomineral systems. The
contribution by Ruiz-Hitzky’s Group reviews different
bio-nanocomposites based on gelatin, in particular those related
to inorganic layered solids, such as clay minerals (smectites)
and metal mixed-oxides (perovskites).
On the other hand, nanoscale systems based on porous membranes
offer the possibility to synthesize materials within nanopores,
which also constitutes an improved way for advanced separation
techniques and sensing purposes. This important aspect has
been reviewed by Martin’s Group at the University of
Florida based on their own experience, discussing in their
contribution various synthetic strategies, as well as recent
advances on nanotube membranes for biotechnological applications.
The Group of Choy, in Korea (Center for Intelligent Nano-Bio
Materials, CINBM) contributes with a review emphasizing on
DNA based hybrids with multipurpose applications, from drug
delivery systems to gene therapy. In addition, two contributions,
related to the sensing ability of bio-nanohybrids have been
elaborated by Briones & Martín-Gago as well as
by Forano’s Group, the former centered on the development
of DNA microarrays and the last one dealing with enzyme-based
bio-nanohybrids useful for bio-sensing devices.
Every contribution presented in this Special Issue reflects
recent advances in the emerging field of bio-hybrid nanostructured
materials showing the remarkable properties that arise from
the nanostructure of supramolecular assembling of inorganic
solids and biomolecules giving promising biologically active
artificial systems.
We would like to sincerely acknowledge the support and cooperation
extended by the Manager Publications Miss Aniza Irshad of
Bentham Science Publishers Ltd. throughout the processes to
prepare this Special Issue of CNANO.
Eduardo R uiz -Hitz ky
Margarita Darder
Instituto de Ciencia de Materiales de Madrid, CSIC, 28049-
Madrid, Spain
[Back to top]
Nanostructured Biomaterials for Regenerative Medicine
Vinoy Thomas, Derrick R. Dean and Yogesh K. Vohra
An ideal 3D-scaffold for tissue regeneration should have similarity
to native ECM in terms of both chemical composition and physical
nanostructure. Recently, nanostructured biomaterials having
physical nanofeatures such as nanocrystals, nanofibers nanosurfaces,
nanocomposites, etc. gained much interest in regenerative
medicine. This is mainly because of their resemblance of physical
nanofeatures to natural extra cellular matrices. This review
mainly focuses on nanocrystalline bioresrobable bioceramic
scaffolds and nanofibrous polymeric scaffolds for tissue regeneration.
Fabrication of porous bioceramics based on HA and other calcium
phosphates with interconnected pore structure can be done
by the replication of polymer foam. The advantage of this
technique is the control over porosity, pore geometry and
pore size of the fabricated scaffolds. Therefore, the first
part of the review focused on porous nanocrystalline bioceramics
for bone tissue engineering. Electrospinning is a versatile
technique to fabricate nanofibrous polymeric matrices for
use in regenerative medicine. The recent developments in electrospun
scaffolds with a special emphasis on FDA approved biodegradable
polymers such as PCL, PLA, PLGA, collagens, etc are presented
in the second part. A special attention has been made to review
the mechanical properties and cell interaction of the electrospun
mats. Electrostatic co-spinning of polymers with nanohydroxyapatite
to fabricate hybrid nanocomposite scaffolds as potential scaffolds
mimicking the complex nanostructured architecture of bone
has been suggested for hard tissue regeneration.
[Back to top]
Nanostructured Hybrid Materials for Bone Tissue Regeneration
María Vallet-Regí and Daniel Arcos
The study of materials for bone tissue repair is one of the
most important subjects in the field of materials research
for biomedical applications. Bone can be considered as a biological
hybrid material composed of an organic component, collagen,
and an inorganic one, nanocrystalline carbonate hydroxyapatite
(CHA). Both phases integrate each other into a nano-metrical
scale in such a way that the crystallite size, nanofibers
orientation, short range order between both components, etc.
determine its nanostructure and therefore the function and
mechanical properties of each kind of bone. On the basis of
bone regeneration, new biomaterials have been developed. These
materials stimulate the bone tissue formation by promoting
the osteoblast proliferation and differentiation. One of the
most promising alternatives is to apply materials with similar
nanostructure to that of natural bone tissue. In this sense,
the nanotechnology and the development of organic-inorganic
hybrid materials provide excellent possibilities for improving
the conventional bone implants. The present article reviews
the advances in silicate –containing hybrids for bone
tissue repair, as well as the chemical methodologies that
allow to control the material nanostructure. Special attention
is paid to bioactive hybrid materials, which are able to produce
biological apatites on their surfaces when they are in contact
with physiological fluids.
[Back to top]
Properties of Hydroxyapatite – Hyaluronic Acid
Nano-Composite Sol and its Interaction with Natural Bones
and Collagen Fibers
Yuichi Ishikawa, Jun Komotori and Mamoru Senna
Biocompatible nano-composite sol (NCS) comprising nano-crystalline
hydroxyapatite (HAp, Ca10(PO4)6(OH)2)
and hyaluronic acid (HYA) was prepared. By varying the relative
content of HAp in NCS, strongest network structure was obtained
at 10wt% HAp in NCS, as confirmed from a number of circumstance
evidences obtained by rheological, thermoanalytical, crystallographical
measurements as well as FT-IR spectra. Interaction of NCS
with natural bones and gut strings made from gut collagen
was then examined in vitro. Adhesion of the collagen
fibers with NCS was observed at the fracture surface of natural
bones. Gut collagen was disentangled to the fragments of about
10 nm thick, where no NCS was observed, thus, confirming the
fact that the adhesive strength between NCS and bone surface
is stronger than that among collagen fibers.
[Back to top]
Recent Progresses in Bio-Inorganic Nanohybrids
Katsuhiko Ariga, Ajayan Vinu and Masahiko Miyahara
This review presents a comprehensive overview of the recent
advances in the field of bio-inorganic nanohybrids. In the
first part of this review, examples on hybridization of biomembrane
mimics with inorganic backbone are described. Silane-bearing
amphiphile was used for the preparation of Langmuir-Blodgett
films that are mechanically stable and capable of permeation
controls and electrode modification with vitamin function.
The similar amphiphiles were utilized to form organic-inorganic
hybrid vesicle "Cerasome", which can be assembled
in layer-by-layer manner to construct multi-cellular mimic.
Furthermore, the potential applications of the above materials
are reviewed and proposed. The second part of this review
provides the methodology of immobilizing various biomolecules
into nanosized inorganic structures including clay minerals
and layer-by-layer (LBL) assemblies. Films and hollow capsules
prepared through the LBL techniques offer sophisticated designs
of the bio-inorganic nanohybrids that can be applied to biomaterial
entrapment and bio-reactors. Examples on hybridization of
biomolecules with mesoporous inorganic structure are also
introduced in the last part. A controlled release of biochemical
drugs and immobilization of bio-assemblies on the materials
with well-defined pore structures in nanometer ranges are
briefly examined, discussed and summarized.
[Back to top]
Enzymes and Bio-Molecular Assemblies in Nano-Spaces
of Mesoporous Silica
Yoshiaki Fukushima, Tsutomu Kajino and Tetsuji Itoh
The incorporation of bio-molecules and proteins into inorganic
host materials has been given great attention recently. The
present paper deals with the preparation, structures and properties
of conjugates of mesoporous silica: folded sheet mesoporous
materials (FSM), with chlorophyll (Mg-porphyrin) and heme
(ferriprotoporphyrin). Horseradish peroxidase, light harvesting
protein and myoglobin were also adsorbed in mesoporous silica
of adequate pore size. The molecules and proteins adsorbed
in the mesopores were stabilized according to temperature
change, oxidation and/or light irradiation. The porphyrin/FSM
conjugates showed characteristic performance resembling that
of the light harvest system in natural leaves, myoglobin or
catalase. The stabilized proteins in FSM also maintained their
own functions. These results suggested that bio-inspired assembly
technologies in nanospaces are valuable tools for the design
and preparation of catalysts, adsorbents, membranes and energy
conversion devices.
[Back to top]
Sol-Gel Biopolymer/Silica Nanocomposites in Biotechnology
Thibaud Coradin, Joachim Allouche, Michel Boissière
and Jacques Livage
Bioencapsulation in silica gels has become a very popular
field of research, leading to the design of biosensors and
bioreactors. If pure silica gels appear suitable to maintain
the biological activity of entrapped enzymes, there are many
cases where hybrid materials are necessary to reach the long-term
preservation of biomolecular or cellular species and/or to
provide new functionalities. This review focuses on the design
of such nanocomposite materials combining silica with biopolymers.
In the first part, the synthesis and characterization of these
bio-hybrid materials are described, emphasizing the importance
of the polymer influence on the reactivity of silica precursors.
In the second part, the benefits of biopolymer incorporation
in silica gels are illustrated in the context of biotechnological
devices. As a conclusion, a parallel is drawn between biohybrids
and biominerals, opening new perspectives for the design of
multi-component biologically-active materials.
[Back to top]
Bio-Nanohybrids Based on Layered Inorganic Solids:
Gelatin Nanocomposites
Margarita Darder, Ana Isabel Ruiz, Pilar Aranda, Henri
Van Damme and Eduardo Ruiz-Hitzky
An emerging group of hybrid materials is the so-called bio-nanocomposites,
which are bio-hybrid nanostructured materials based on the
combination of natural polymers (polysaccharides, proteins,
enzymes, nucleic acids) and inorganic solids (clays, double
layered hydroxides, phosphates, metal oxides, etc.). Bio-nanocomposites
are interesting because, among other properties, the use of
biopolymers provides biocompatibility, non-toxicity and biodegradability
to the resulting nanohybrid materials. An example of this
type of natural polymers is gelatin, a polypeptide derived
from the structural protein collagen, that is able to form
transparent, elastic and thermoreversible gels. This paper
will review the role of inorganic solids, such as montmorillonite
or perovskite, in combination with gelatin, on the characteristics
and final properties of different type of bio-nanocomposites
based on this protein. With these examples, we will show the
influence of the solids on the gelatin gel-transition temperature,
film formation ability and rheological, mechanical and dielectric
properties.
[Back to top]
Nanopore Membranes for Biomaterials Synthesis, Biosensing
and Bioseparations
Lane A. Baker, Youngseon Choi and Charles R. Martin
We have developed techniques and methods based on porous membranes
for applications in bionanotechnology. There are three general
membrane-based strategies we have used to prepare our nanoscale
systems. In the first method, namely, template synthesis,
nanometer scale pores are used to synthesize and modify materials.
We have shown that template synthesis is highly adept at producing
biomaterials with at least one dimension that is nanometer
in scale. In the second strategy, we describe chemical and
biochemical sensors based on nanotube membranes. These sensors
function largely by monitoring variations in the ionic currents
through the pores of the membranes that develop under an applied
transmembrane potential. In the third approach, nanometer
scale pores are used to separate species that translocate
a nanotube membrane. The selectivity and flux of species that
translocate the nanotube membrane can be further controlled
through chemical modification of the nanotube walls. In this
review, we will discuss these three uses of nanotube membranes
(template synthesis, sensing and separation) in the context
of biotechnology and biomaterials. We will briefly review
the materials and methods of nanotube membrane technology
and then discuss our most recent bio-oriented research of
these interesting systems.
[Back to top]
Nucleic Acids and Their Analogs as Nanomaterials
for Biosensor Development
Carlos Briones and José Ángel Martín-Gago
Nucleic acids are natural biopolymers that store the genetic
information of organisms. This makes the detection and characterization
of DNA and RNA a relevant task in biotechnology, with applications
ranging from medicine to environmental control. During the
last decades, a large effort has been focused on the development
of biosensors, among them those devoted to the detection of
nucleic acids in natural samples and those that include nucleic
acids as nanosized capture probes for different biomolecules.
DNA microarray technology has been successfully used in biotechnological
applications including genotyping and gene expression studies.
Nevertheless, the performance of DNA microarrays has a limitation
imposed by the need of a previous fluorescent labeling of
the target molecule to be analyzed. This encouraged the use
of alternative detection methods, such as optical and electrochemical
ones, and recently others based on surface characterization
techniques. New trends in nanotechnology point towards new
tools for manipulating molecules and macromolecules that could
be developed as high performance biosensors. This interdisciplinary
approach towards the integration of novel biosensors can benefit
from the capability of certain polymers to form self-assembled
monolayers (SAMs) on different surfaces. Thiol-modified DNA
can form SAMs on gold surfaces with reduced efficiency, and
the biological activity of the probe is decreased upon adsorption.
Therefore, thiolated DNA has a very limited use in biosensor
development. These constraints have been successfully by-passed
using uncharged, artificial analogs of natural nucleic acids,
such as peptide nucleic acids (PNAs), as molecular probes.
This contribution reviews the state of the art in the use
of nucleic acids and their analogs as biosensor nanomaterials,
and summarizes the novel approach towards the development
of biosensors based on SAMs of PNAs. Finally, we present the
current trends in this promising aspect of nanobiotechnology.
[Back to top]
Bio-Nanohybrids Based on Layered Double Hydroxide
Jin-Ho Choy, Man Park and Jae-Min Oh
Layered double hydroxides (LDHs) with high anion exchange
capacity have attracted particular attention in the fields
of bio-hybrid nanomaterials due to their unique properties
such as excellent biocompatibility, high affinity to carbonate
anion, pH-dependent stability and high availability. To date,
a variety of negatively charged biomolecules have been hybridized
with LDHs to evolve into bio-LDH nanohybrids, including vitamins,
drugs and DNA strands as well as simple organic acids. Bio-LDH
nanohybrids can be readily prepared in a mild condition by
coprecipitation, anion exchange or reconstruction. Their applications
can be found in a wide range from the controlled release and
delivery systems to biosensors and genetic molecular code
system. In this review, special emphasis has been placed on
DNA-LDH nanohybrids because DNA molecules are of great importance
in many sciences and industrial fields. Their synthesis methods,
characteristics and application potentials are reviewed briefly.
[Back to top]
Nanohybrid Enzymes - Layered Double Hydroxides: Potential
Applications
Claude Forano, Stéphanie Vial and Christine Mousty
Bioinorganic hybrid materials constitute a new generation
of materials at the interface of biology and material science,
able to display functionalities as complex as that of natural
systems such as drug vectorization and delivery, molecular
machinery functions or sensing properties. Among these bioinorganic
structures, enzyme-clay nanohybrid compounds are under investigations
for applications as biosensors or for biosynthesis applications.
Due to their anionic exchange properties, wide range of chemical
composition and versatile structural and textural properties,
layered double hydroxides are very appropriate materials for
the immobilization of biomolecules, which often bear an overall
negative charge. This review focuses on the strategy of elaboration
procedures of new active bioinorganic LDH-enzyme materials
with potential applications in biocatalysis and for the elaboration
of biosensors. Various soft chemistry processes such as adsorption,
delamination/restacking and coprecipitation methods are examined.
Structural and textural characterizations of the bioinorganic
materials are described in order to understand the interactions
between biomolecules and host structure. Bioactivity of immobilized
enzymes and electrochemical performance of biosensors are
also discussed in relation with the immobilization state of
the enzyme.
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