2. Polylactic Acid
• Polylactic acid (PLA): is a bio-based plastic derived from renewable resources such as fermented corn starch, sugarcane, or tapioca roots.
It has a variety of advantages in industrial applications and is an excellent promising replacement for non-degradable petroleum-based
polymers like polypropylene, polyethylene, or polystyrene. Advantages of PLA over conventional plastics include its availability, eco-
friendliness, biocompatibility, competitive cost, and its ease of biodegradability and processability into final products.
Preparation of polylactic acid
• Extraction and fermentation of biomass (corn starch, sugarcane etc) by microorganisms to produce a metabolic byproduct known as
lactic acid (LA).
• Purification of LA: high-purity LA is exctracted and purified by various separation techniques, such as filtration, distillation, or
crystallization.
• Polymerization of LA: The isolated LA undergos direct or indirect condensation polymerization reactions at high temperature to eliminate
water molecules, resulting to formation of PLA polymer chains.
• PLA Processing: The resulting PLA polymer is further processed by extrusion and molding into finished products like bottles, sheets, films,
and other biodegradable devices
3. Hydroxyapatite
• Hydroxyapatite (HA): is a naturally occurring mineral form of calcium apatite, which is the main component of human
bones and teeth. HA can be obtained from natural sources like animal bones or synthesized in the laboratory. HA is a
white, crystalline powder that closely resembles the mineral composition of human bones and teeth. HA is a
relatively hard material, providing structural support. HA offers excellent biocompatibility and osteoconductivity,
making it an ideal material for bone regeneration and repair applications. Its similarity to natural bone and slow
resorption rate further contribute to its effectiveness and long-term stability.
Preparation of Hydroxyapatite
• Precursor preparation: A calcium source (e.g., calcium nitrate, calcium hydroxide) and a phosphate source (e.g.,
diammonium hydrogen phosphate, ammonium phosphate) are dissolved in water to create separate solutions.
• Mixing: The calcium and phosphate solutions are then mixed together while maintaining a controlled pH and temperature.
This mixing allows for the formation of the desired hydroxyapatite precipitate.
• Aging: The mixture is aged for a specific period to allow the hydroxyapatite crystals to grow and stabilize.
• Filtration and washing: The precipitated hydroxyapatite is separated from the solution using filtration techniques. It is then
washed with water or a suitable solvent to remove any impurities or residual chemicals.
• Drying: The washed hydroxyapatite is dried either by air drying or using a drying oven. Care is taken to prevent excessive
heat that could cause phase transformations or degradation of the hydroxyapatite.
4. Applications
• Sustainable Packaging: PLA can replace traditional plastic packaging in
various industries, reducing the environmental impact and promoting
sustainability.
• 3D Printing: PLA is a popular material for 3D printing due to its ease of
processing and biodegradability.
• Drug Delivery Systems: PLA-based nanoparticles can be used to
encapsulate and deliver drugs with controlled release, enhancing therapeutic
efficacy.
• Tissue Engineering: Both PLA and HA are used in tissue engineering to
create scaffolds that support cell growth and facilitate the regeneration of
damaged tissues.
• Bone Grafting: Composite materials made of PLA and HA are used as bone
graft substitutes, providing a framework for bone growth and eventually
being replaced by natural bone tissue.
• Dental: HA is used in dental composites, fillings, and coatings due to its
biocompatibility and ability to integrate with natural teeth.
