Polymeric Bowl-Shaped Nanoparticles: Hollow Structures with a Large Opening on the Surface

Polymeric bowl-shaped nanoparticles (BNPs) are anisotropic hollow structures with large openings on the surface, which have shown advantages such as high specific area and efficient encapsulation, delivery and release of large-sized cargoes on demand compared to solid nanoparticles or closed hollow structures. Several strategies have been developed to prepare BNPs based on either template or template-free methods. For instance, despite the widely used self-assembly strategy, alternative methods including emulsion polymerization, swelling and freeze-drying of polymeric spheres, and template-assisted approaches have also been developed. It is attractive but still challenging to fabricate BNPs due to their unique structural features. However, there is still no comprehensive summary of BNPs up to now, which significantly hinders the further development of this field. In this review, the recent progress of BNPs will be highlighted from the perspectives of design strategies, preparation methods, formation mechanisms, and emerging applications. Moreover, the future perspectives of BNPs will also be proposed.

Magnetic nanoparticles and magnetic particle spectroscopy-based bioassays: a 15 year recap

Magnetic nanoparticles (MNPs) have unique physical and chemical properties, such as high surface area to volume ratio and size-related magnetism, which are completely different from their bulk materials. Benefiting from the facile synthesis and chemical modification strategies, MNPs have been widely studied for applications in nanomedicine. Herein, we firstly summarized the designs of MNPs from the perspectives of materials and physicochemical properties tailored for biomedical applications. Magnetic particle spectroscopy (MPS), first reported in 2006, has flourished as an independent platform for many biological and biomedical applications. It has been extensively reported as a versatile platform for a variety of bioassays along with the artificially designed MNPs, where the MNPs serve as magnetic nanoprobes to specifically probe target analytes from fluid samples. In this review, the mechanisms and theories of different MPS platforms realizing volumetric- and surface-based bioassays are discussed. Some representative works of MPS platforms for applications such as disease diagnosis, food safety and plant pathology monitoring, drug screening, thrombus maturity assessments are reviewed. At the end of this review, we commented on the rapid growth and booming of MPS-based bioassays in its first 15 years. We also prospected opportunities and challenges that portable MPS devices face in the rapidly growing demand for fast, inexpensive, and easy-to-use biometric techniques.

Transparent Conductive Silk Film with a PEDOT-OH Nano Layer as an Electroactive Cell Interface

Bioelectronics based on biomaterial substrates are advancing toward biomedical applications. As excellent conductors, poly(3,4-ethylenedioxythiophene) (PEDOT) and its derivatives have been widely developed in this field. However, it is still a big challenge to obtain a functional layer with a good electroconductive property, transparency, and strong adhesion on the biosubstrate. In this work, poly(hydroxymethyl-3,4-ethylenedioxythiophene) (PEDOT-OH) was chemically polymerized and deposited on the surface of a regenerated silk fibroin (RSF) film in an aqueous system. Sodium dodecyl sulfate (SDS) was used as the surfactant to form micelles which are beneficial to the polymer structure. To overcome the trade-off between transparency and the electroconductive property of the PEDOT-OH coating, a composite oxidant recipe of FeCl₃ and ammonium persulfate (APS) was developed. Through electrostatic interaction of oppositely charged doping ions, a well-organized conductive nanoscale coating formed and a transparent conductive RSF/PEDOT-OH film was produced, which can hardly be achieved in a traditional single oxidant system. The produced film had a sheet resistance (R_s) of 5.12 × 10⁴ Ω/square corresponding to a conductivity of 8.9 × 10^-2 S/cm and a maximum transmittance above 73% in the visible range. In addition, strong adhesion between PEDOT-OH and RSF and favorable electrochemical stability of the film were demonstrated. Desirable transparency of the film allowed real-time observation of live cells. Furthermore, the PEDOT-OH layer provided an improved environment for adhesion and differentiation of PC12 cells compared to the RSF surface alone. Finally, the feasibility of using the RSF/PEDOT-OH film to electrically stimulate PC12 cells was demonstrated.

Glycan Stimulation Enables Purification of Prostate Cancer Circulating Tumor Cells on PEDOT NanoVelcro Chips for RNA Biomarker Detection

A glycan-stimulated and poly(3,4-ethylene-dioxythiophene)s (PEDOT)-based nanomaterial platform is fabricated to purify circulating tumor cells (CTCs) from blood samples of prostate cancer (PCa) patients. This new platform, phenylboronic acid (PBA)-grafted PEDOT NanoVelcro, combines the 3D PEDOT nanosubstrate, which greatly enhances CTC capturing efficiency, with a poly(EDOT-PBA-co-EDOT-EG3) interfacial layer, which not only provides high specificity for CTC capture upon antibody conjugation but also enables competitive binding of sorbitol to gently release the captured cells. CTCs purified by this PEDOT NanoVelcro chip provide well-preserved RNA transcripts for the analysis of the expression level of several PCa-specific RNA biomarkers, which may provide clinical insights into the disease.

Hollow polymer nanocapsules: synthesis, properties, and applications

Hollow polymer nanocapsules (HPNs) have gained tremendous interest in recent years due to their numerous desirable properties compared to their solid counterparts.

Sensing Conductive Hydrogels for Rapid Detection of Cytokines in Blood

Conducting polymer hydrogel is fabricated atop gold or ITO electrodes and is functionalized with monoclonal antibodies. Binding of interferon-γ molecules causes redox properties of conductive hydrogel to change in a concentration-dependent fashion without the need for washing or sample handling steps. This conductive hydrogel remains functional in a fouling media such as whole blood.

Syntheses and biomedical applications of hollow micro-/nano-spheres with large-through-holes

This review mainly discussed the syntheses and biomedical applications of hollow micro-/nano-spheres with large-through-holes in shells.

Polydioxythiophene nanodots, nonowires, nano-networks, and tubular structures: the effect of functional groups and temperature in template-free electropolymerization

Various nanostructures, including nanofibers, nanodots, nanonetwork, and nano- to microsize tubes of functionalized poly(3,4-ethylenedioxythiophene) (EDOT) and poly(3,4-propylenedioxythiophene) (ProDOT) are created by using a template-free electropolymerization method on indium-tin-oxide substrates. By investigating conducting polymer nanostructures containing various functional groups prepared at different polymerization temperature, we conclude a synergistic effect of functional groups and temperature on the formation of polymer nanostructures when a template-free electropolymerization method is applied. For unfunctionalized EDOT and ProDOT, or EDOT containing alkyl functional groups, nanofibers and nanoporous structures are usually found. Interesting, when polar functional groups are attached, conducting polymers tend to form nanodots at room temperature while grow tubular structures at low temperature. The relationship between surface properties and their nanostructures is evaluated by contact angle measurements. The capacity and electrochemical impedance spectroscopy measurements were conducted to understand the electrical properties of using these materials as electrodes. The results provide the relationship between the functional groups, nanostructures, and electrical properties. We also discuss the potential restriction of using this method to create nanostructures. The copolymerization of different functionalized EDOTs may cause irregular and unexpected nanostructures, which indicates the complex interaction between different functionalized monomers during the electropolymerization.