75 research outputs found
Fabrication of multiphasic and regio-specifically functionalized PRINT ® particles of controlled size and shape
Using Particle Replication In Nonwetting Templates (PRINT®) technology, multiphasic and regio-specifically functionalized shape-controlled particles have been fabricated that include end-labeled particles via post-functionalization; biphasic Janus particles that integrate two compositionally different chemistries into a single particle; and more complex multiphasic shape-specific particles. Controlling the anisotropic distribution of matter within a particle creates an extra parameter in the colloidal particle design, providing opportunities to generate advanced particles with versatile and tunable compositions, properties, and thus functionalities. Owing to their robust characteristics, these multiphasic and regio-specifically functionalized PRINT particles should be promising platforms for applications in life science and materials science
Reductively Responsive siRNA-Conjugated Hydrogel Nanoparticles for Gene Silencing
A critical need still remains for effective delivery of RNA interference (RNAi) therapeutics to target tissues and cells. Self-assembled lipid- and polymer-based systems have been most extensively explored for transfection with small interfering RNA (siRNA) in liver and cancer therapies. Safety and compatibility of materials implemented in delivery systems must be ensured to maximize therapeutic indices. Hydrogel nanoparticles of defined dimensions and compositions, prepared via a particle molding process that is a unique off-shoot of soft lithography known as PRINT (Particle Replication in Non-wetting Templates), were explored in these studies as delivery vectors. Initially, siRNA was encapsulated in particles through electrostatic association and physical entrapment. Dose-dependent gene silencing was elicited by PEGylated hydrogels at low siRNA doses without cytotoxicity. To prevent disassociation of cargo from particles after systemic administration or during post-fabrication processing for surface functionalization, a polymerizable siRNA pro-drug conjugate with a degradable, disulfide linkage was prepared. Triggered release of siRNA from the prodrug hydrogels was observed under a reducing environment while cargo retention and integrity were maintained under physiological conditions. Gene silencing efficiency and cytocompatibility were optimized by screening the amine content of the particles. When appropriate control siRNA cargos were loaded into hydrogels, gene knockdown was only encountered for hydrogels containing releasable, target-specific siRNAs, accompanied by minimal cell death. Further investigation into shape, size, and surface decoration of siRNA-conjugated hydrogels should enable efficacious targeted in vivo RNAi therapies
The effect of particle design on cellular internalization pathways
The interaction of particles with cells is known to be strongly influenced by particle size, but little is known about the interdependent role that size, shape, and surface chemistry have on cellular internalization and intracellular trafficking. We report on the internalization of specially designed, monodisperse hydrogel particles into HeLa cells as a function of size, shape, and surface charge. We employ a top-down particle fabrication technique called PRINT that is able to generate uniform populations of organic micro- and nanoparticles with complete control of size, shape, and surface chemistry. Evidence of particle internalization was obtained by using conventional biological techniques and transmission electron microscopy. These findings suggest that HeLa cells readily internalize nonspherical particles with dimensions as large as 3 μm by using several different mechanisms of endocytosis. Moreover, it was found that rod-like particles enjoy an appreciable advantage when it comes to internalization rates, reminiscent of the advantage that many rod-like bacteria have for internalization in nonphagocytic cells
Reductively Responsive siRNA-Conjugated Hydrogel Nanoparticles for Gene Silencing
A critical need still remains for effective delivery
of RNA interference
(RNAi) therapeutics to target tissues and cells. Self-assembled lipid-
and polymer-based systems have been most extensively explored for
transfection with small interfering RNA (siRNA) in liver and cancer
therapies. Safety and compatibility of materials implemented in delivery
systems must be ensured to maximize therapeutic indices. Hydrogel
nanoparticles of defined dimensions and compositions, prepared via
a particle molding process that is a unique off-shoot of soft lithography
known as particle replication in nonwetting templates (PRINT), were
explored in these studies as delivery vectors. Initially, siRNA was
encapsulated in particles through electrostatic association and physical
entrapment. Dose-dependent gene silencing was elicited by PEGylated
hydrogels at low siRNA doses without cytotoxicity. To prevent disassociation
of cargo from particles after systemic administration or during postfabrication
processing for surface functionalization, a polymerizable siRNA pro-drug
conjugate with a degradable, disulfide linkage was prepared. Triggered
release of siRNA from the pro-drug hydrogels was observed under a
reducing environment while cargo retention and integrity were maintained
under physiological conditions. Gene silencing efficiency and cytocompatibility
were optimized by screening the amine content of the particles. When
appropriate control siRNA cargos were loaded into hydrogels, gene
knockdown was only encountered for hydrogels containing releasable,
target-specific siRNAs, accompanied by minimal cell death. Further
investigation into shape, size, and surface decoration of siRNA-conjugated
hydrogels should enable efficacious targeted in vivo RNAi therapies
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