New graphene-based material developed for medical implants

Education, Engineering, Science, Research,

Bengaluru May 1st 2019 (India science Wire): A group of scientists have developed a new material for biomedical applications by combining a graphene-based nanomaterial with Hydroxyapatite (HAp), a commonly used bioceramic in implants.

By Susheela Srinivas

In recent years, biometallic implants have become popular
as a means to repair, restructure or replace damaged or diseased parts in
orthopaedic and dental procedures. Metal parts also find use in devices such as
pacemakers.  

However, metallic implants face several limitations
and are not a permanent solution. They react with body fluids and corrode, release
wear and tear debris resulting in toxins and inflammation. They also have high
thermal expansion and low compressive strength causing pain and are dense and
may cause reactions.

On the other hand, bioceramics do not have these
limitations. HAp specifically is osteoconductive, with a bone-like porous
structure offering the required scaffold for tissue re-growth. However, it is
brittle and lacks the mechanical strength of metals. The problem is overcome by
combining it with nanoparticles of materials such as Zirconia.

In the new research, scientists have combined HAp with
graphene nanoplatelets. “Previously
reported studies have focused on only structural properties of such composites without
throwing light on their biological properties. We have found that combining HAp with graphene nanomaterial enhances
mechanical strength, provides better in-vivo imaging and biocompatibility
without changing its basic bone-like properties,” explained Dr Gautam
Chandkiram, the principal investigator at University of Lucknow, while speaking to India
Science Wire
.

Purification of the base ceramic material is a
significant primary challenge in fabricating composites. According to
scientists, in the current study, highly efficient biocompatible Hydroxyapatite was
successfully prepared via a microwave irradiation technique and the consequent composites
was synthesised using a simple solid-state reaction method.

The process involved mixing different concentrations
of graphene nanoplatelet powders and drying, crushing, sieving and ball-milling
the resulting slurry. The fine composite powder was further cold-compressed and
sintered at 1200 degrees Celsius to achieve the desired density.

The scientists found that the composite
had adequate interfacial area between the nanoparticles, with the graphene nanoplatelets
well distributed into the hydroxyapatite matrix, while exhibiting high fracture
resistance.  Further, structural characterization,
mechanical and load bearing tests showed that the 2D nature of graphene
improves the load transfer efficiency significantly.

Researchers also examined cell viability of the composite by observing metabolic activity in specific cells using a procedure known as MTT assay. They used gut tissues of Drosophila larvae and primary osteoblast cells of a rat. “The overall cell viability studies demonstrated that there is no cytotoxic effect of the composites on any cell type,” explained Dr. Gautam.

Biomaterials also find use in drug delivery and bioimaging diagnosis. “Our research on the composite found that it displays a better fluorescence behaviour as compared to pure hydroxyapatite, indicating it has a great potential in bone engineering and bioimaging bio-imaging applications as well,” he added. The research team included Sunil Kumar and Gautam Chandkiram (Advanced Glass and Glass Ceramics Research Laboratory, University of Lucknow); Vijay Kumar Mishra and Ritu Trivedi (CSIR-Central Drug Research Institute, Lucknow); Brijesh Singh Chauhan, Saripella Srikrishna, Ram Sagar Yadav and Shyam Bahadur Rai (Banaras Hindu University). The study results have been published in the journal ACS Omega.

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