Microspheres are tiny spherical particles that range from nanometers to millimetres in diameter. They are manufactured using a variety of synthetic and natural polymers as well as ceramics and glass. They have intriguing properties like biocompatibility and enable controlled, sustained release of drugs, proteins, cells and genes inside the body. Due to these advantages, they find a wide range of applications in fields such as healthcare, life sciences and biomedical engineering.
Types
They can be broadly classified based on their composition and properties. Some common types include:
- Polymeric: Made of polymers like polylactic acid (PLA), polyglycolic acid (PGA). They are biodegradable and used for sustained drug delivery.
- Ceramic: Composed of materials like calcium phosphate, alumina. Used as carriers for bioactive molecules and fillers for bone repair applications.
- Gel: Formed using natural polymers like alginate, chitosan. Used as scaffolds for tissue engineering due to hydrogel properties.
- Magnetic: Contain magnetic nanoparticles embedded in a polymer matrix. Help in targeted drug/cell delivery through magnetic guidance.
- Porous: Have interconnected pores rendering high surface area. Ideal carriers for larger molecules and cells.
Manufacturing Methods
Several techniques are employed for its fabrication depending on the material and application. The most common ones include:
- Spray drying: Involves atomizing a solution/melt into a hot chamber forming dried upon solvent evaporation. Used for water-soluble and heat-stable polymers.
- Solvent evaporation: A polymer is dissolved in a volatile solvent which is then emulsified/dispersed in a non-solvent. Extraction of the solvent solidifies the polymer into . Ideal for water-insoluble polymers.
- Phase separation/coacervation: Involves separating desired and non-desired phases of a colloidal suspension using changes in temperature, pH or addition of salts. Allows fabrication of gel Microspheres.
- Ionotropic gelation: Natural polymers like alginate form gel beads in the presence of divalent cations like calcium. Hydrogel form instantaneously through crosslinking.
- Spray-congealing/spray-cooling: Suitable for thermosetting polymers, ceramics and glasses. Melt atomization followed by cooling in gas yields uniformly sized microspheres.
Medical Applications
Due to their tunable characteristics, they are excellent vehicles for targeted drug and gene delivery besides various tissue engineering applications. Some key uses are detailed below:
Cancer Therapy
Chemotherapeutic drugs can be encapsulated in them for sustained release at the tumor site. This controlled delivery spares healthy tissues and improves therapeutic efficacy. Radiolabeled help deliver high-dose radiation locally for treatment of cancerous tumors like hepatocellular carcinoma.
Vaccine Delivery
biodegradable type containing antigens, immune stimulants and targeting ligands are being developed as improved vaccine delivery systems. They elicit both humoral and cell-mediated immune responses for infectious diseases and cancer immunotherapies.
Tissue Regeneration
Microspheres laden with growth factors, proteins and stem cells serve as minimally invasive injectable scaffolds for regeneration of tissues like bone, cartilage, muscle and dermal substitutes.
Ocular Drug Delivery
Microsphere-based intravitreal implants are promising alternatives to frequent eye drops/injections for retinal diseases. They gradually release drugs achieving higher ocular bioavailability over months.
Other Applications
Its formulations are also studied for targeted treatment of cardiovascular diseases, joint disorders, neurological conditions and skin diseases while overcoming issues with conventional dosage forms. Their utilization is likely to increase manifold in the future of advanced drug delivery and regenerative medicine.
They exhibit tunable physico-chemical properties and enable sustained release of therapeutics. Their biomedical applications are numerous and still expanding at a fast pace alongside technology improvements. With continued research to optimize microsphere characteristics, this technology holds tremendous promise for developing next-generation solutions across healthcare. They may emerge as an important pillar of individualized precision medicine in the future through customizable, localized drug and cell-based therapies.
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Money Singh is a seasoned content writer with over four years of experience in the market research sector. Her expertise spans various industries, including food and beverages, biotechnology, chemical and materials, defense and aerospace, consumer goods, etc. (https://www.linkedin.com/in/money-singh-590844163)
