Preparation of nano-sized particles from collagen II by a high-voltage electrostatic field system

Enhanced differentiation of rat MSCs into cardiomyocytes with 5-azacytidine/collagen I nano-molecules

This study was to investigate the enhancement ability of 5-azacytidine (5-aza) and collagen I nano-molecules treatment to the differentiation of rat mesenchymal stem cells (MSCs) towards a cardiomyocytes in vitro. The results demonstrated that the size of the cells increased significantly and connecting with adjoining cells by forming myotube-like structures. Also, additional treatment of the MSCs with collagen I nano-fibrils significantly increased two transcription factors GATA-4 and Nkx2.5 expressions and three expressions of cardiac genes of troponin I, β-myosin heavy chain and cardiac α-actin compared with MSC groups treated only with 5-aza at early 3 d culturing(all, P<0.01 or better). These results indicate that culturing MSCs with collagen I nano-molecules, which could act as scaffolds or soluble protein ingredients, leads to alterations in gene expression and affects the differentiation fate induced with 5-aza.

Collagen for bone tissue regeneration

In the last decades, increased knowledge about the organization, structure and properties of collagen (particularly concerning interactions between cells and collagen-based materials) has inspired scientists and engineers to design innovative collagen-based biomaterials and to develop novel tissue-engineering products. The design of resorbable collagen-based medical implants requires understanding the tissue/organ anatomy and biological function as well as the role of collagen's physicochemical properties and structure in tissue/organ regeneration. Bone is a complex tissue that plays a critical role in diverse metabolic processes mediated by calcium delivery as well as in hematopoiesis whilst maintaining skeleton strength. A wide variety of collagen-based scaffolds have been proposed for different tissue engineering applications. These scaffolds are designed to promote a biological response, such as cell interaction, and to work as artificial biomimetic extracellular matrices that guide tissue regeneration. This paper critically reviews the current understanding of the complex hierarchical structure and properties of native collagen molecules, and describes the scientific challenge of manufacturing collagen-based materials with suitable properties and shapes for specific biomedical applications, with special emphasis on bone tissue engineering. The analysis of the state of the art in the field reveals the presence of innovative techniques for scaffold and material manufacturing that are currently opening the way to the preparation of biomimetic substrates that modulate cell interaction for improved substitution, restoration, retention or enhancement of bone tissue function.

A PERSPECTIVE VIEW ON THE PREPARATION OF MICRO- AND NANOPARTICULATES OF BIOMATERIALS FROM ELECTROSTATIC AND ULTRASONIC METHODS

Developments on tissue engineering, especially on tissue regeneration and drug delivery, demand also developments on biomaterials. Research on the preparation methods of biomaterials has exhibited remarkable advances in the recent years. Natural biomaterials, such as chitosan and collagen, or synthetic materials like poly(lactic acid) can be shaped in various forms. The parameters involved in the fabrication processes provide methodologies for control of the materials' properties, such as morphology, biodegradability, mechanical strength, and adhesion. As new applications develop for these materials, the preparation methods have to be optimized to achieve the desired material properties. These properties mostly not only mimic the conditions in the human body, but also may divert the microenvironment of cells in the diseased area in order to promote faster or guided healing and tissue regeneration. This review pays attention on some of the fabrication methods for biomaterial particulates of sizes in the micro- and nanoscale. The views expressed here focus on the many years of experience of the authors with electrostatic and ultrasonic fabrication methods. These methods are still under development and up to now can produce particulates of various sizes down to the nanometer scale with narrow size distributions. Such biomaterials that have extraordinary properties may provide ways for the development of remarkable biomedical applications.

Electrospraying, spray drying and related techniques for production and formulation of drug nanoparticles

IMPORTANCE OF THE FIELD

Spray drying and electrospraying are two widely used liquid atomization-based techniques for production and formulation of drug nanoparticles. The importance of spray drying in particular has increased lately in the production of nanostructured microparticles. The value of the particles is that they maintain the properties of individual nanoparticles but they are micrometer sized.

AREAS COVERED IN THIS REVIEW

In this review the most important liquid atomization techniques, spray drying and electrospraying, are presented in detail, and a short introduction is presented for other methods, including the aerosol flow reactor method and spray congealing.

WHAT THE READER WILL GAIN

A description of the possible tailoring processes depending on the technique and process parameters. Different product properties can be achieved; for example, nanosuspensions or dry powder formulations may be produced.

TAKE HOME MESSAGE

The most important advantage of these techniques as compared with many other particle formation techniques is that the production of dried powders is possible without any extra drying step.