"Clickable" polymer nanoparticles: a modular scaffold for surface functionalization

PEGylated and functionalized polylactide-based nanocapsules: An overview

Polymeric nanocapsules (NC) are versatile mixed vesicular nanocarriers, generally containing a lipid core with a polymeric wall. They have been first developed over four decades ago with outstanding applicability in the cosmetic and pharmaceutical fields. Biodegradable polyesters are frequently used in nanocapsule preparation and among them, polylactic acid (PLA) derivatives and copolymers, such as PLGA and amphiphilic block copolymers, are widely used and considered safe for different administration routes. PLA functionalization strategies have been developed to obtain more versatile polymers and to allow the conjugation with bioactive ligands for cell-targeted NC. This review intends to provide steps in the evolution of NC since its first report and the recent literature on PLA-based NC applications. PLA-based polymer synthesis and surface modifications are included, as well as the use of NC as a novel tool for combined treatment, diagnostics, and imaging in one delivery system. Furthermore, the use of NC to carry therapeutic and/or imaging agents for different diseases, mainly cancer, inflammation, and infections is presented and reviewed. Constraints that impair translation to the clinic are discussed to provide safe and reproducible PLA-based nanocapsules on the market. We reviewed the entire period in the literature where the term "nanocapsules" appears for the first time until the present day, selecting original scientific publications and the most relevant patent literature related to PLA-based NC. We presented to readers a historical overview of these Sui generis nanostructures.

Drug-Loaded Polymeric Spherical Nucleic Acids: Enhancing Colloidal Stability and Cellular Uptake of Polymeric Nanoparticles through DNA Surface-Functionalization

Small-sized (∼65 nm) doxorubicin (Dox)-loaded polymeric nanoparticles (PNPs) were modified with oligonucleotides to form colloidally stable Dox-loaded polymeric spherical nucleic acid (Dox-PSNA) nanostructures in biological media. The nucleic acid shell facilitates the cellular uptake of Dox-PSNA, which results in in vitro cytotoxicity against SKOV3 cancer cells.

Correction: Hood, M.A., et al. Synthetic Strategies in the Preparation of Polymer/Inorganic Hybrid Nanoparticles. Materials 2014, 7, 4057-4087

In [1], several sentences were repeated three times on pages 4062, 4063 and 4065. In addition, many references were incorrect. The errors were introduced by the editorial office during the editing process. We apologize for this mistake and any inconvenience this may have caused to authors and readers. The corrected manuscript is given below.[...].

One-step synthesis of dual clickable nanospheres via ultrasonic-assisted click polymerization for biological applications

Dual clickable nanospheres (DCNSs) were synthesized in one step using an efficient approach of ultrasonic-assisted azide-alkyne click polymerization, avoiding the need of surfactants. This novel approach presents a direct clickable monomer-to-nanosphere synthesis. Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and dynamic laser scattering (DLS) were used to characterize the synthesized DCNSs. Numerous terminal alkynyl and azide groups on the surface of DCNSs facilitate effective conjugation of multiple molecules or ligands onto a single nanocarrier platform under mild conditions. To exemplify the potential of DCNSs in biological applications, (1) multivalent glyconanoparticles (GNPs) were prepared by clicking DCNSs with azide-functionalized and alkyne-functionalized lactose sequentially for the determination of carbohydrate-galectin interactions with quartz crystal microbalance (QCM) biosensor. Using protein chip (purified galectin-3 coated on chip) and cell chip (Jurkat cells immobilized on chip), the QCM sensorgrams showed excellent binding activity of GNPs for galectins; (2) fluorescent GNPs were prepared by clicking DCNSs with azide-functionalized Rhodamine B and alkyne-functionalized lactose sequentially in order to target galectin, which is overexpressed on the surface of Jurkat cells. The fluorescent images obtained clearly showed the cellular internalization of fluorescent GNPs. This fluorescent probe could be easily adapted to drugs to construct lectin-targeted drug delivery systems. Thus, DCNSs prepared with our method may provide a wide range of potential applications in glycobiology and biomedicine.

Synthetic Strategies in the Preparation of Polymer/Inorganic Hybrid Nanoparticles

This article reviews the recent advances and challenges in the preparation of polymer/inorganic hybrid nanoparticles. We mainly focus on synthetic strategies, basing our classification on whether the inorganic and the polymer components have been formed in situ or ex situ, of the hybrid material. Accordingly, four types of strategies are identified and described, referring to recent examples: (i) ex situ formation of the components and subsequent attachment or integration, either by covalent or noncovalent bonding; (ii) in situ polymerization in the presence of ex situ formed inorganic nanoparticles; (iii) in situ precipitation of the inorganic components on or in polymer structures; and (iv) strategies in which both polymer and inorganic component are simultaneously formed in situ.

Dumbbells, trikes and quads: organic-inorganic hybrid nanoarchitectures based on "clicked" gold nanoparticles

The controlled assembly of gold nanoparticles in terms of the spatial arrangement and number of particles is essential for many future applications like electronic devices, sensors and labeling. Here an approach is presented to build up oligomers of mono functionalized gold nanoparticles by the use of 1,3-bipolar azide alkyne cycloaddition click chemistry. The gold nanoparticles of 1.3 nm diameter are stabilized by one dendritic thioether ligand comprising an alkyne function. Together with di-, tri- and tetra-azide linker molecules the gold nanoparticle can be covalently coupled by a wet chemical protocol. The reaction is tracked with IR and UV-vis spectroscopy and the yielded organic-inorganic hybrid structures are analyzed by transmission electron microscopy. To evaluate the success of this click chemistry reaction statistical analysis of the formed oligomers is performed. The geometric and spatial arrangements of the found oligomers match perfectly the calculated values for the used linker molecules. Dimers, trimers and tetramers could be identified after the reaction with the corresponding linker molecule. The results of this model reaction suggest that the used click chemistry protocol is working well with mono functionalized gold nanoparticles.

ROMP (co)polymers with pendent alkyne side groups: post-polymerization modification employing thiol–yne and CuAAC coupling chemistries

The synthesis of a series of copolymers via ring-opening metathesis polymerization (ROMP) containing pendent trimethylsilyl-protected alkyne functional groups is described.

Smart Nanoscale Drug Delivery Platforms from Stimuli-Responsive Polymers and Liposomes

Since the 1960's, stimuli-responsive polymers have been utilized as functional soft materials for biological applications such as the triggered-release delivery of biologically active cargos. Over the same period, liposomes have been explored as an alternative drug delivery system with potentials to decrease the toxic side effects often associated with conventional small-molecule drugs. However, the lack of drug-release triggers and the instability of bare liposomes often limit their practical applications, causing short circulation time and low therapeutic efficacy. This perspective article highlights recent work in integrating these two materials together to achieve a targetable, triggerable nanoscale platform that fulfills all the characteristics of a near-ideal drug delivery system. Through a drop-in, post-synthesis modification strategy, a network of stimuli-responsive polymers can be integrated onto the surface of liposomes to form polymer-caged nanobins, a multifunctional nanoscale delivery platform that allows for multi-drug loading, targeted delivery, triggered drug-release, and theranostic capabilities.

Signal amplification using functional nanomaterials for biosensing

Signal amplification based on biofunctional nanomaterials has recently attracted considerable attention due to the need for ultrasensitive bioassays and the trend towards miniaturized assays. The biofunctional nanomaterials can not only produce a synergic effect among catalytic activity, conductivity and biocompatibility to accelerate the signal transduction, but also provide amplified recognition events by high loading of signal tags, leading to a highly sensitive and specific biosensing. Most importantly, nanoscaled materials are in direct contact with the environment, which permits them to act as chemical and biological sensors in single-molecule detection of biomolecules. In this tutorial review, we will focus on recent significant advances in signal amplification strategies combining the cross-disciplines of chemistry, biology, and materials science, and highlight some elegant applications of biofunctional nanomaterials as excellent electronic or optical signal tags in ultrasensitive bioanalysis. The biofunctional nanomaterials-based biosensing opens a series of concepts for basic research and offers new tools for detection of trace amounts of a wide variety of analytes in clinical, environmental, and industrial applications.

Improved anti-proliferative effect of doxorubicin-containing polymer nanoparticles upon surface modification with cationic groups

Polymer nanoparticles (PNPs) possessing a high density of drug payload have been successfully stabilized against aggregation in biological buffers after amine modification, which renders these PNPs positively charged. The resulting charge-stabilized PNPs retain their original narrow particle size distributions and well-defined spherical morphologies. This stabilization allows these PNPs to have an improved anti-proliferative effect on MDA-MB-231-Br human breast cancer cells compared to non-functionalized PNPs. As a non-cytotoxic control, similar surface-modified PNPs containing cholesterol in place of doxorubicin did not inhibit cell proliferation, indicating that the induced cytotoxic response was solely due to the doxorubicin release from the PNPs.