A biomaterial used as a matrix for bone regeneration and made by a porous block of 1 cm height, which was obtained from beer bagasse treatment. (Source: CMM-CSIC and ICP-CSIC/Angeles Martin Luengo, Malcolm Yates and Eduardo Sáezl)

A new method combines beer-brewing waste (and other agricultural residues) to make bone biomaterials

At first blush it is a bit disingenuous, using beer waste as a base material for new bone. But that is exactly what a multidisciplinary team of researchers in Spain has come up with in a process for making the substrate material on which bone can be regenerated.

The researchers have developed biocompatible materials from food industry waste, mainly bagasse– the spent grain waste from the beer brewing process. These new bone biomaterials are being considered as alternatives to traditional prostheses made from synthetic materials. They could provide a significantly cheaper alternative that avoids the use of toxic chemicals during their manufacture.

The work helps to lower the cost of such biomaterials and it provides a valuable use for a waste product, said M. Angeles Martin-Luengo, of the Instituto de Ciencia de Materiales (ICMM), Madrid, Spain, and one of the researchers on the project. The team reported the advance in RSC Advances, a publication of the Royal Society of Chemistry, in the article “Preparation, characterization and in vitro osteoblast growth of waste-derived biomaterials.”

The researchers “used agri-residues based on beer bagasse but also residues from rice production, fruits and vegetables,” Martin-Luengo said. “The use of these residues helps the economy and the environment.”

The researchers considered bagasse because it contains the main chemical components found in bone (phosphorous, calcium, magnesium and silica), Martin-Luengo noted.  After undergoing modification processes, the waste is transformed into a material that can be used as support or scaffold to promote bone regeneration for medical applications like coating prostheses or bone grafts.

“The work published to date is based on studying the thermal transformations, but since then we have found several ways to optimize the biomaterials by combining thermal, chemical, composition and structural modifications,” she explained.

The bagasse modifying steps used include drying, calcination, chemical treatment to change composition and formation into blocks that can be conformed to measure.

Currently, synthetic materials are primarily used as substitutes in the treatment of bone diseases. These therapeutic strategies are based on materials that provide stiff, but porous, scaffolds made of biocompatible materials that are used as molds. The molds provide the mechanical stability and promote growth of new bone tissue that helps in its regeneration.

Synthetic calcium phosphates are frequently used as matrices and coatings for orthopedic implants because of their resemblance to the composition of bone. These materials are often obtained through chemical synthesis that uses toxic reagents (like benzoyl peroxides, benzene and aniline) and require calcinations at temperatures of close to 1500 C.

In the new process, the researchers were able to obtain bioceramics, after simply adding silicon through the hydrolysis of TEOS and sintering the resultant material to more than 1100 C.

There are distinct cost advantages to the new material– the cost of commercial synthesized materials is about 150 euros ($200) per gram, and bagasse is sold as fertilizer for 40 euros ($53) per ton. But the true test of the material is how it performs.

Martin-Luengo said analysis of this new material shows the presence of interconnected pores of between 50 and 500 microns in diameter, which is similar to the porosity of cancellous bone. She said this could facilitate the complete vascularization after a bone implant.

A first approach using cell cultures has established the biocompatibility of the materials by analyzing the cell viability of cultured osteoblasts in the presence of powder material components.  Then, after compacting and sintering the materials that became three-dimensional solid matrices, the ability of bone-like cells to adhere to these materials were analyzed.

Also, the researchers analyzed how these materials proliferate and distinguish from the mature bone cells, which are able to express typical markers of bone phenotype such as alkaline phosphatase, and to conduct the collagen synthesis and mineralization of the extracellular matrix.

Martin-Luengo said the research was, in part, spurred on by the oral surgical treatment of one member of the research team, as well as the need to develop a less expensive material.

“The main importance of the dental treatment for our research was realizing the high price of the biomaterials used to fill the jaw bone (150 euros per gram) and the composition of waste derived materials being that of improved biomaterials, due to extra magnesium and silicon,” she said.

The team includes researchers from the Universidad Politecnica de Madrid and Consejo Superior de Investigaciones Cientificas in collaboration with Mahou and Createch Co.