Biomaterials: what they are, types and characteristics

Human beings (and most animals) have some ability to heal wounds and injuries. Normally, openings of the epidermis by mechanical processes follow a medically predictable healing mechanism: clot formation, inflammation, cell proliferation and differentiation of the new strains, in order to remodel the tissue and return it to its original state to the greatest extent possible. possible.

In any case, not only the epidermis is repaired. Bone consolidation and mobilization of myocyte satellite cells (in bone and muscle, respectively), are examples of other physiological mechanisms that try to heal microtears and fractures in our apparatus locomotor.

For example, when there is a fracture in a bone, the cell bodies (osteocytes, osteoblasts, osteoclasts and cells osteoprogenitors) secrete and remodel the bone matrix, in order to achieve that the bone recovers its normal shape in the minor possible time. Typically, within 6 to 8 weeks, significant improvement can be seen.

Unfortunately, not all tissues heal well and some totally lack perfect regenerative capacity, such as the heart or other organs. To challenge the limits of human physiological capabilities and potentially save millions of lives,

biomaterials come to our times. Learn everything about them, because the future of medicine is the least promising.

• Related article: "Main Cell Types of the Human Body"

What are biomaterials?

A biomaterial, from a medical point of view, is any natural or synthetic material intended to be introduced into living tissue, especially as part of a surgical element or implant. At a physiological level, these materials have unique properties compared to the rest, since they can contact with living tissue immediately without causing negative immune responses in the patient.

In addition, it should be noted that biomaterials they do not achieve their function through the segregation of pharmacological substances and do not depend on metabolization by the organism to achieve the desired effect (otherwise, we would be talking about drugs). Their mere functionality and magic is found in being (and adapting) in the right place, since they ideally serve to supplant any hard or soft tissue that has suffered some type of damage. In addition to their typical use, they are also increasingly used as diagnostic methods and other clinical events.

The first generation of biomaterials was conceived in about 1940, with a peak of utility and function in the 1960s and 1970s. As medical knowledge and materials have been refined, the capabilities of these elements have been improving over time, giving rise to compounds of the second and third generation. Some of its ideal properties are the following:

• Appropriate mechanical properties: a highly rigid biomaterial cannot be introduced into a loose natural tissue, as its correct functionality would be impeded.
• Resistance to corrosion in an aqueous medium: the human body is 60% water. Therefore, that the biomaterial is resistant to water stress is essential.
• It should not promote local toxicity or carcinogenic events in the tissue in which it is placed.
• From the second generation, it was sought that the materials were also bioactive. These should induce a physiological response that supports the function and performance of the biomaterial.
• Another of the new characteristics sought is that some of the materials were capable of being reabsorbed. This means that they disappear or change drastically over time and can be metabolized by the body.
• Finally, today it is expected that some of them stimulate specific responses at the cellular level.

As you can imagine, the ideal properties of a biomaterial depend entirely on the functionality. For example, a surgeon wants a screw applied to fix a graft in ligament injuries to reabsorb over time, so the patient does not have to intervene again. On the other hand, if the biomaterial replaces a vital structure, the idea is that it is permanent and resists all the elements of the body ecosystem.

Besides, some biomaterials are interesting from a cellular point of view, since they can develop their growth and differentiation. For example, some third-generation bioactive crystals are designed to activate certain genes in damaged tissue cells, in order to promote rapid regeneration. It seems like a technology taken from a dystopian future, but this is a reality today.

Types of biomaterials

So that all of the above does not remain in a series of ethereal concepts, we present you with proof of the usefulness of biomaterials. We cannot cover them all (as the list is very long), but we do collect some of the most interesting ones. Do not miss it.

1. Calcium Phosphate Ceramics

Porous calcium phosphate ceramics can be used to repair certain intrabony defects, as they they are not toxic, they are biocompatible with the organism and they do not significantly alter the levels of calcium and phosphorus in the blood. In any case, as bioceramics are eminently hard and degrade very slowly, it is usually necessary to combine them with biodegradable polymers to achieve better results.

These types of implants are used to promote bone recovery in fractures, for example. As a curious fact, it has been observed that imbuing these biomaterials with mesenchymal stem cells can promote faster and better tissue regeneration in certain animals. As you can see, a biomaterial is not just a mineral or compound, but a mixture of organic and inorganic elements that try to find the perfect balance to achieve its functionality.

2. bioactive crystals

Bioactive crystals are also ideal for certain regenerative processes at the bone level, since their degradation rate can be controlled, they secrete certain ionic materials with osteogenic potential and they have a more than correct affinity meeting with bone tissue. For example, multiple studies have shown that some bioactive crystals promote the activation of osteoblasts, bone tissue cells that secrete intercellular matrix that give bone its strength and functionality.

• You may be interested in: "The 12 branches (or fields) of Psychology"

3. Resorbable bicortical screws

Resorbable plates and screws based on polylactic and polyglycolic acids are the order of the day, since they increasingly replace the hard titanium elements that brought so many problems when welding injuries.

For example, polyglycollate is a strong, non-rigid material that does not fray and offers good security as an abutment during suturing. These materials far outperform titanium in that they cause much less patient discomfort, are less expensive, and do not require surgical removal.

4. biomaterial patches

Until now we have mentioned biomaterials that are used for bone regeneration, but they are also used in soft tissues. For example, the National Institute of Biomedical Imaging and Bioengineering is developing alginate patches, based on brown algae, as therapeutic sealants to treat lung infiltrations from trauma, surgery, or conditions such as pneumonia and cystic fibrosis.

The results of these technologies are promising, as alginate patches appear to respond well to pressures similar to those exerted by the lungs and help tissue regeneration in these organs so essential for life.

5. Hydrogel “bandage” for burns

People who suffer from severe burns experience real agony when their bandages are handled and, furthermore, these retard epidermal growth and tissue regeneration. By using hydrogels that are currently being studied, this series of problems could disappear.

The hydrogel would act as an ideal film to prevent infection and degradation caused by environmental inclemencies in the wound.. In addition, it could dissolve at the rate of certain controlled procedures and expose the lesion without the mechanical stress that this entails. Without a doubt, this would infinitely improve the hospital stay of patients with severe burns.

Summary

Everything we have told you is not based on conjectures and hypotheses: many of these materials are already in use today, while others are currently being actively developed.

As you can see, the future of medicine is, to say the least, promising. With the discovery and refinement of biomaterials, infinite possibilities open up, from the reabsorption of screws and sutures to the integration of elements in the tissues that promote the activation of healing mechanisms own. Undoubtedly, reality is stranger than fiction in the field of medicine.

Bibliographic references:

• Bhat, S., & Kumar, A. (2013). Biomaterials and bioengineering tomorrow's healthcare. Biomatter, 3(3), e24717.
• Biomaterials, NIH. Collected on March 20 in https://www.nibib.nih.gov/science-education/science-topics/biomaterials
• Griffith, L. g. (2000). Polymeric biomaterials. Act materialia, 48(1), 263-277.
• Hubbell, J. TO. (1995). Biomaterials in tissue engineering. Bio/technology, 13(6), 565-576.
• Navarro, M., Michiardi, A., Castano, O., & Planell, J. TO. (2008). Biomaterials in orthopedics. Journal of the royal society interface, 5(27), 1137-1158.
• Park, J., & Lakes, R. S. (2007). Biomaterials: an introduction. Springer Science & Business Media.
• Ratner, B. D., & Bryant, S. J. (2004). Biomaterials: where we have been and where we are going. Annu. Rev. Biomed. Eng., 6, 41-75.