Biomedical Engineering Reference
In-Depth Information
field of imaging functionalization of HBP-based delivery systems is still in its
infancy, interdisciplinary research will facilitate its maturation in this area and
assist the exploitation of drugs.
5.3.4 Biodegradability and Biocompatibility
The long-term accumulation of these external vehicles, which cannot be
degraded or metabolized, is detrimental to the human body. Therefore,
excellent biodegradability and biocompatibility are of particular importance
for the design of new biomedical polymeric vehicles. From this perspective,
hyperbranched polyesters have become increasingly important in the
biomedical field due to the general ease of metabolization of the degradation
products. In addition, the introduction of functional components is able to
facilitate the property alteration of the polymers, e.g. post-modification with
hydrophilic blocks or bio-ligands. Thurecht et al. constructed water-soluble,
degradable core-shell nanoparticles.
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The nanoparticles were composed of the
biodegradable core-shell HBPs via reversible addition-fragmentation chain
transfer polymerization (RAFT) of N,N-dimethylamino-2-ethyl methacrylate
and ring opening polymerization (ROP) of e-caprolactone. The accelerating
degradation of the hyperbranched materials with different crosslinking
densities suggested that they could be used in the manufacture of controlled
drug delivery systems. In addition, Liu et al. prepared a series of biodegradable
hyperbranched polyphosphates which exhibited potential value as drug
carriers.
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The promising delivery systems of the newly emerging
hyperbranched polyphosphates show high biodegradability and biocompat-
ibility. With the readily available feedstocks and newly developed chemistries,
more and more biodegradable and biocompatible materials will be discovered
for biomedical applications.
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5.3.5 Multifunctionality
The single function of the delivery system is not able to satisfy the needs of
both smart and programmable delivery systems, so multifunctional delivery
systems need to be designed, such as the combination of imaging and
responsiveness. On the one hand, preparing multifunctional HBP-based
nanocarriers with controlled properties requires the conjugation of recognition
agents, imaging agents, reporter groups, or other functional ligands to the
carrier surface. On the other hand, functional components may be loaded
inside the nanocarriers or dispersed within the HBP structures by means of
noncovalent attachments, such as hydrogen bonding interactions, host-guest
interactions, and hydrophobic adsorption of certain intrinsic or specially
inserted hydrophobic groups. Multifunctional pharmaceutical HBP-based
nanocarriers could enlarge the horizon of producing highly efficient and
specialized delivery systems for drugs and genes. Such multifunctional systems
should allow pharmaceutical agents to release in a required temporal and
