Biomaterials: Everything you should know

Have you ever thought about the substance used in medicines or implants? What is the smooth colorful outer covering of pills or the material of the lens made of? If not, then maybe we could help you with filling in some details. All these materials come under the category of biomaterials. Biomaterials play a great role in the medical and healthcare sectors. It can be natural or synthetic, living or non-living materials and they are usually composed of multiple components. 

What are biomaterials?

A biomaterial is defined as a substance that is engineered to take a shape, either alone or as part of a complex system, generally used for the interaction with biological systems for mainly medical purposes, for either any diagnostic purpose or therapeutic one (treat, repair, replace or augment). In laymen’s language, biomaterials are those materials that interact with the biological system with no side effects.

According to Merriam-Webster, biomaterials are defined as the material that comes in direct contact with the living system like the tissue, used for prostheses. It is a non-viable material. Biomaterials are non-drug materials, utilized in treating, enhancing, or replacing any tissue, organ, or function in an organism. 

Main features of biomaterials:

  • Biocompatibility: Biocompatibility is an important property of biomaterials. It is the property of a material to execute a suitable or appropriate host response for a particular application. The material is biocompatible only if it does not produce any harmful reaction to the body on exposure. Biocompatible materials should not produce any toxic effects or immunological rejection, also should not be physiologically reactive. 
  • Biofunctionality: This property of biomaterial describes whose mechanical and physical function is dependent on biological function. 

Types of biomaterials:

Biomaterials are classified into three categories according to the reactivity of material with living tissue. These are of the following types-

  1. BIOINERT MATERIALS:

Bioinert or biologically inert materials are the materials that once placed in the body have minimal interaction with the surrounding tissue. Being inert, they do not initiate any response or interact when exposed to the tissue. The prime reason for choosing these materials is because the materials which initiate a response can cause detrimental effects on the host. Few examples of bioinert materials are titanium, alumina, stainless steel, partially stabilized zirconia, phosphorylcholine, and ultra-high molecular weight polyethylene.

  1. BIOACTIVE MATERIALS:

The bioactive or biologically active materials are non-toxic, biologically active materials that induce chemical bond formation between the implant and the host tissue. It can interact with bone and even soft tissue. These materials can either be natural (gelatin, collagen, agarose, fibrin, silk, chitosan, etc.) or synthetic (metals, polymers, ceramics, hydrogels, composites, etc.). These biomaterials elicit a specific biological response. The main examples of bioactive materials are synthetic hydroxyapatite [Ca10(PO4)6(OH)2], carotenoids, bioceramic glasses, polyphenols, and many more.

  1. BIORESORBABLE MATERIALS:

Bioresorbable or biodegradable materials refer to a material that starts getting dissolved (resorbed) upon placement within the human body. The human body can solubilize, degrade, or phagocytose these materials. They have innumerable applications, especially in medicine and surgery. They find application in stents for blood vessels as well as for other internal ducts. It can be either synthetic or natural. Some examples of bioresorbable biomaterials are gypsum, calcium oxide (CaO), tricalcium phosphate [Ca3(PO4)2], Calcium carbonate (CaCO3), and poly(lactic-co-glycolic) acid, cross-linked polyester hydrogels, etc.

Applications of biomaterials:

Imagining the medical sector without biomaterials is impossible. They have a broad range of applications in different fields-

  1. Body implants, including stents, heart valves, grafts, hearing loss implants, and artificial joints. Orthopedic implants use materials like chromium, polyethylene, and ceramics (for instance, alumina, zirconia).
  1. Biosensors detects the presence as well as the amount of specific substances. Examples are blood glucose, cardiac markers, prosthetic devices, etc.
  1. One of the oldest applications of biomaterials is in wound healing. Suture materials comes under biomaterials. The most widely used synthetic suture material are polymers. Suture materials include some metals like stainless steel and tantalum.
  1. It has many dental applications such as in cases of cavities, root canal treatment, and other dental problems. Materials used as dental implants are alumina and carbon. Orthodontic wires use Ni-Ti and for dental restoration, Hg-Ag amalgam, and gold alloys. 
  1. The eye tissues are very sensitive and thus, can be prone to several ailments which may lead to reduced vision and subsequently leading to blindness. Thus, biomaterials has application in ophthalmics. Intraocular lens (IOL) is a polymer, used for replacing the lens in case of cataract. 
  1. The other applications are drug-delivery systems, regenerated human tissue, molecular probes, etc.

Recent advances and future:

Biomaterials are an integral part of the healthcare industry. The current market size of biomaterials is US$ 35.5 billion in 2020. This will increase at a CAGR of 6% and the global market size will increase to US$ 47.5 billion by 2025. 

Hearing aid

In the first quarter of 2020, the COVID-19 pandemic disrupted its market. During this period, many dental procedures and surgeries were delayed. However, the market will recover in the coming two years as the data suggests. Standard biomaterials, for instance, ceramics, metals, and synthetic polymers are bioinert materials. But recently developed biomaterials are designed to mimic natural tissues as much as possible that can provide biological functions. Many developments and research is being done in drug delivery, especially for cancer drug delivery system, in tissue engineering, implantable hearing devices, and almost all domains of biomaterials for future use.

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