PHD → Inorganic chemistry → Bio-inorganic chemistry ↓
The role of metals in medicine
Metals have played important roles in the history of medicine, contributing to many therapeutic practices and helping to diagnose, prevent or treat various diseases. The use of metals in medicine is a fascinating field at the intersection of chemistry, biology and medicine, which is explored through bioinorganic chemistry. This branch of chemistry involves the study of metal-containing compounds within biological systems and has applications in healthcare, particularly through the development of drugs and diagnostics.
Introduction to bio-inorganic chemistry
Bioinorganic chemistry is a field that investigates the role of metals in biological systems. It includes the study of metalloenzymes, metal ion transport and storage, and the mechanisms by which metal ions interact with biological molecules. Metals play important roles in a variety of physiological processes—they are key components of many biomolecules and serve as essential cofactors for enzymes.
Medical applications of bioinorganic chemistry focus on both the beneficial and toxicological aspects of metals in medicine, creating therapeutic agents, imaging agents, and understanding the implications of metal toxicity. The study of metals in medicine also involves investigating how metal ions can be used to develop new therapeutic and diagnostic tools.
Metals as therapeutic agents
Some metal ions and metal complexes are well established as therapeutic agents, and new metal-based drugs are continually under development. Here are some of the most common examples:
Platinum-based drugs
Platinum-based drugs, such as cisplatin
, carboplatin
and oxaliplatin
, are the most widely used chemotherapeutic agents. The first of these drugs, cisplatin, was approved for cancer treatment in the 1970s and works by binding to DNA, causing structural changes that lead to apoptosis (controlled cell death) in cancer cells.
Pt(NH3)2Cl2
These drugs have revolutionized the treatment of a number of cancers, including testicular, ovarian, bladder, and lung cancers, although they often come with side effects due to their lack of specificity for individual cancer cells.
Gold compounds
Gold compounds have been used in medicine for many years. Gold-based drugs are used in the treatment of rheumatoid arthritis, with aurothiomalate
being one example. These drugs work by regulating the immune system, reducing inflammation, and reducing joint damage and pain.
Gold complexes are also being investigated for their potential use in cancer therapy due to their unique properties and ability to selectively induce cell apoptosis.
Silver compounds
Silver and its compounds are well-known for their antimicrobial properties. Silver sulfadiazine cream is widely used to prevent and treat bacterial infections in burn wounds, taking advantage of silver's bactericidal activity. This application highlights the dual role of metals in medicine - both as therapeutic and preventive agents.
Metals in clinical medicine
Metals are essential in various diagnostic imaging techniques, where they enhance the visibility of internal structures. Here are some examples of how metals facilitate diagnostic procedures:
Magnetic resonance imaging (MRI)
MRI is a non-invasive imaging technique that relies on the use of gadolinium-based contrast agents. Gadolinium is a rare earth metal with unique magnetic properties, which enhances contrast during imaging by altering the relaxation time of protons in body tissues.
Gadolinium, when chelated, is used in intravenous contrast agents to highlight blood vessels and inflamed tissue, providing physicians with detailed images for accurate diagnosis.
[Gd(DOTA)]-
Computed tomography (CT)
Iodine and barium are often used as contrast agents in CT scans. Although iodine is not a metal, it is often found with metal ions in specific formulations. These contrast agents effectively absorb X-rays and enhance the contrast of the resulting CT images, helping in the diagnosis of vascular diseases and gastrointestinal disorders.
For example, barium sulfate is given orally to patients undergoing a barium swallow test. The dense nature of barium allows for detailed imaging of the digestive tract.
Nuclear medicine
In nuclear medicine, radionuclides of metals such as technetium (^99Tc
) are used for imaging. Radioactive isotopes emit gamma rays that can be detected by imaging instruments, allowing bodily functions to be observed and abnormal processes such as tumors or infections to be identified.
^99Tc
is widely used in radiopharmaceuticals because of its optimal half-life, low radiation dose, and the ability to form a variety of compounds suitable for imaging of different organs.
Iron in biological systems
Iron is a fundamental component of hemoglobin, the protein responsible for transporting oxygen in the blood. Iron's oxygen-carrying ability is due to its ability to undergo oxidation-reduction reactions, which equate to a gain or loss of electrons.
Fe2+ ⇌ Fe3+ + e-
Iron deficiency can cause anemia, which includes fatigue, weakness, and a lack of oxygen to the tissues. Treatment usually involves iron supplementation, highlighting iron's essential role in maintaining health.
Copper and zinc in enzyme function
Copper and zinc are important cofactors for enzymes that play key roles in metabolic processes. Copper is essential in enzymes such as cytochrome c oxidase, which are part of the electron transport chain, a vital component of cellular respiration.
Zinc is critical for proper immune function and is integral to the structure and function of many enzymes, including carbonic anhydrase and zinc finger proteins. These metalloenzymes are involved in processes ranging from maintaining acid-base balance to regulating gene expression.
Visual example
Conclusion
Metals are integral to diagnostic and therapeutic strategies in modern medicine. As research in bioinorganic chemistry progresses, new metal-based drugs and diagnostic agents have the potential to improve patient outcomes. Understanding the complex roles of metals in biological systems enables the advancement of innovative medical solutions, offering hope in fighting challenging diseases. The journey of metals from the periodic table to clinical application forms a rich fabric that weaves chemistry through the fabric of life.