Biomaterials and Macromolecules - Add? Flashcards
for drug delivery
What are biomaterials?
Materials designed for medical applications that support, enhance or replace biological functions. Enables targeted and controlled drug delivery, reducing systemic side effects and improving therapeutic outcomes.
Can be broadly categorised into:
Natural – high biocompatibility and bioactivity, batch variability and limited mechanical strength. Used for wound healing, drug carriers and tissue scaffolds. E.g. collagen, alginate, chitosan
Synthetic – controlled degradation, tuneable properties, low biocompatibility and potential toxicity issues. Used for controlled drug release, medical implants, tissue engineering for load-bearing regions. E.g. PEG, PLA, PCL, PEEK
Hybrid materials – combining synthetic and natural elements. Used for bone grafts, 3D-printed implants and regenerative medicine. E.g. gelatin-methacryloyl (GelMA) for 3D tissue printing
Describe polymer biomaterials
Large macromolecules designed for controlled and sustained drug release
e.g. PLGA nanoparticles are used for sustained chemotherapy drug release (Lupron depot for prostate cancer)
Common in chemotherapy, pain management and insulin therapy
Describe hydrogel biomaterials
Hydrophilic polymer networks that swell in water and allow controlled drug diffusion
e.g. GelMA hydrogels for growth factor release in wound healing applications
Describe ceramic biomaterials
Inorganic materials used in biodegradable and bioactive implants
e.g. hydroxyapatite-coated implants for localised antibiotic release in bone infections
Describe metal biomaterials
Durable biomaterials used in implants, coatings and controlled drug release systems
e.g. paclitaxel-eluting stents to prevent artery blockages in cardiovascular disease
Describe carbon-based biomaterials
Nanostructured materials like carbon nanotubes (CNTs), graphene and fullerenes used for drug transport and sensing
e.g. functionalised CNTs for targeted anticancer drug delivery
Describe inorganic nanoparticles
Gold, silver, silica-based nanoparticles for imaging and therapy
e.g. iron oxide nanoparticles for MRI-guided drug delivery
Describe liposomes and lipid-based carriers
Phospholipid vesicles (liposomes, micelles, solid lipid nanoparticles) encapsulating drugs, have reduced toxicity and enhanced targeted therapy
e.g. liposomal doxorubicin for targeted cancer therapy
Used in chemotherapy, vaccines and antifungal treatments
Describe smart biomaterials
Biomaterials that respond to environmental stimuli (pH, temperature, enzymes, light etc.) to control drug release. Hydrophilic networks that can hold and release drugs
e.g. pH sensitive hydrogels for targeted chemotherapy drug release in acidic tumour environments, and wound healing
What are the mechanisms of biomaterial degradation?
Hydrolysis
Enzymatic degradation
Oxidative degradation
Describe surface modifications as a way to reduce biomaterial toxicity
Coating surfaces with biocompatible molecules (e.g. collagen, PEG) to reduce immune reactions
Surface functionalisation to promote cell adhesion and minimise inflammation
Describe polymer functionalisation as a way to reduce biomaterial toxicity
Chemical modification of synthetic polymers to enhance biocompatiblility and control degradation rates
e.g. adding bioactive peptides or growth factors to improve cell interactions
Describe the use of hybrid systems as a way to reduce biomaterial toxicity
Combining natural and synthetic elements to achieve a balance between bioactivity and structural integrity
e.g. GelMA-PLGA scaffolds for improved compatibility and controlled release
Describe the incorporation of antioxidants/anti-inflammatory agents as a way to reduce biomaterial toxicity
Embedding therapeutic agents within scaffolds to neutralise oxidative stress and reduce inflammation
e.g. including curcumin or vitamin E in hybrid systems for their antioxidant properties
What are poloxamers?
Groups of block copolymers composed of three distinct blocks:
2 hydrophilic polyethylene oxide side chain blocks
1 hydrophobic polypropylene oxide core block
What are poloxamines?
Composed of hydrophilic polyethylene oxide (EO) blocks and hydrophobic polypropylene oxide (PO) blocks in an X-shape.
These form four arms of EO-PO blocks bonded to a central ethylenediamine moiety
What are thermoreversible gels?
Gels that can change their physical state from liquid to gel and vice versa when temperature is altered
Useful in formulations and biomedical applications (drug delivery, cosmetics, injectable formulations, tissue engineering)
both poloxamers and poloxamine are thermoreversible and amphiphilic so are generally well tolerated by the body
What are poloxamers and poloxamines used for?
Poloxamers - can form gels and micelles and be used as surfactants, they can lower the surface tension of water, forming micelles in aqueous solutions to interact with both water and lipophilic substances
Poloxamines - used as cleaning agents, detergents and lubricants due to surfactant properties
Used as emulsifiers and stabilisers in cosmetic/personal care products, and other formulations where emulsification/dispersion/stabilisation are necessary
Important examples of macromolecules
Aurolase - therapy for selectively destroying solid tumours using near infrared illumination from a laser. It is composed of the laser, an interstitial fiber optic probe for delivery of the laser energy to a site near or in the tumour, and gold nanoparticles (auroshell particles) which absorb near infrared light and convert it into heat.
Currently used for cats and dogs, and human prostate cancer.
Auramine - a dye used as a fluorescent stain for the detection of mycobacteria, binding to mycolic acids in the cell wall and fluorescing yellow under UV light. Mycobacteria causes serious disease including TB and leprosy
Plasma expanders example
Contains poloxamers 188, have a high molecular weight and expand plasma volume.
Used by soldiers who had major bleeding from injuries, the plasma expander maintains the
volume in the body to ensure enough oxygen
are reaching the organs.
Caused some soldiers to have anaphylactic shock. The presence of Sc5b-9 in serum means membrane attack complex (MAC) has formed. The complement activation was through the alternative pathway, due to being magnesium dependent ?
Different races react differently to
poloxamers, due to diet and genetics. If you have more of a specific type of a protein, more poloxamers gets taken up. People with Scandinavian background were more likely to activate MAC
What are dendrimers?
Highly ordered, branched, organic polymeric molecules. They are nano-sized and radially symmetric, with an inner and outer shell.
There are several modifications of peripheral groups that lead to antibody-dendrimer or peptide-dendrimer conjugates.
Dendrimers in drug delivery - dendritic polymers are analogous to protein, enzymes and viruses, and are easily functionalised. dendrimers can either be attached to the periphery or can be encapsulated in their interior voids
