Soft Nanotechnology with Soft Nanoparticles

Abstract

The last decade of research in the physical sciences has seen a dramatic increase in the study of nanoscale materials. Today, "nanoscience" has emerged as a multidisciplinary effort, wherein obtaining a fundamental understanding of the optical, electrical, magnetic, and mechanical properties of nanostructures promises to deliver the next generation of functional materials for a wide range of applications. While this range of efforts is extremely broad, much of the work has focused on "hard" materials, such as Buckyballs, carbon nanotubes, metals, semiconductors, and organic or inorganic dielectrics. Meanwhile, the soft materials of current interest typically include conducting or emissive polymers for "plastic electronics" applications. Despite the continued interest in these established areas of nanoscience, new classes of soft nanomaterials are being developed from more traditional polymeric constructs. Specifically, nanostructured hydrogels are emerging as a promising group of materials for multiple biotechnology applications as the need for advanced materials in the post-genomic era grows. This review will present some of the recent advances in the marriage between water-swellable networks and nanoscience.

Aptamer-Functionalized Hydrogel Microparticles for Fast Visual Detection of Mercury(II) and Adenosine

“…To effectively protect these molecules and interface them with devices at the same time, much research effort has been devoted to developing materials for biosensor immobilization, including on gold, 2,3 silica, 4 carbon nanotubes, 5,6 graphene oxide, 7,8 lipid bilayers, 9 paper materials, 10 and hydrogels. 11,12 Hydrogels are particularly attractive for making optical sensors. [13][14][15][16][17][18][19] Biomolecular immobilization occurs not only on gel surface but also throughout the whole gel matrix, allowing for high loading capacity.…”

Visual optical biosensors based on DNA-functionalized polyacrylamide hydrogels

“…Therefore, smart hydrogels have been designed to sense these stimuli based on gel volume change. A commonly cited example is the poly N-isopropylacrylamide (pNIPAm) hydrogel that shows temperaturedependent volume change [18,19]. At low temperature, the water-polymer interaction is strong and the gel is highly swelled.…”

Light-Sensitive Polymeric Nanoparticles Based on Photo-Cleavable Chromophores

“…The electrostatic stabilization is based on sulfate groups from initiator fragments which are incorporated into polymer chains during the nucleation and growth process. 46 Different ways of stabilization, which in addition offer the possibility of particles size control, are the utilization of either ionic 47 or steric 48 stabilizers or ionic comonomers [49][50] analogous to surfactant free emulsion polymerizations. After complete polymerization, the microgels dispersion is cooled down to room temperature resulting in a swelling of the networks (T < LCST) and a sterical stabilization of the microgels by dangling chains of the outer swollen particle layer.…”

“…53 In addition, precipitation polymerization of functional monomers in the presence of preformed seed particles was demonstrated to yield such complex structures as e.g. (multi-responsive) 54 core/shell microgels 46,55 or hollow hydrogel spheres. 56 Even though this preparation method is one of the most widely investigated routes to hydrogel nanoparticles, several limitations have to be taken into account.…”

“…(meth)acrylic acid is limited as a successful precipitation during the chain growth crucially depends on the overall hydrophobicity of the resulting copolymer. 46 Furthermore, since batch copolymerization of monomers of different reactivity and hydrophilicity was shown to result in core/shell morphologies, 44,57 the preparation of copolymer microgels exhibiting a homogenous distribution of all functionalities is hindered.…”