Prostate-Specific Membrane Antigen Targeted Gold Nanoparticles for Theranostics of Prostate Cancer.

Prostate cancer is one of the most common cancers and among the leading causes of cancer deaths in the United States. Men diagnosed with the disease typically undergo radical prostatectomy, which often results in incontinence and impotence. Recurrence of the disease is often experienced by most patients with incomplete prostatectomy during surgery. Hence, the development of a technique that will enable surgeons to achieve a more precise prostatectomy remains an open challenge. In this contribution, we report a theranostic agent (AuNP-5kPEG-PSMA-1-Pc4) based on prostate-specific membrane antigen (PSMA-1)-targeted gold nanoparticles (AuNPs) loaded with a fluorescent photodynamic therapy (PDT) drug, Pc4. The fabricated nanoparticles are well-characterized by spectroscopic and imaging techniques and are found to be stable over a wide range of solvents, buffers, and media. In vitro cellular uptake experiments demonstrated significantly higher nanoparticle uptake in PSMA-positive PC3pip cells than in PSMA-negative PC3flu cells. Further, more complete cell killing was observed in Pc3pip than in PC3flu cells upon exposure to light at different doses, demonstrating active targeting followed by Pc4 delivery. Likewise, in vivo studies showed remission on PSMA-expressing tumors 14 days post-PDT. Atomic absorption spectroscopy revealed that targeted AuNPs accumulate 4-fold higher in PC3pip than in PC3flu tumors. The nanoparticle system described herein is envisioned to provide surgical guidance for prostate tumor resection and therapeutic intervention when surgery is insufficient.

3D Printing of Photocurable Cellulose Nanocrystal Composite for Fabrication of Complex Architectures via Stereolithography.

The advantages of 3D printing on cost, speed, accuracy, and flexibility have attracted several new applications in various industries especially in the field of medicine where customized solutions are highly demanded. Although this modern fabrication technique offers several benefits, it also poses critical challenges in materials development suitable for industry use. Proliferation of polymers in biomedical application has been severely limited by their inherently weak mechanical properties despite their other excellent attributes. Earlier works on 3D printing of polymers focus mainly on biocompatibility and cellular viability and lack a close attention to produce robust specimens. Prized for superior mechanical strength and inherent stiffness, cellulose nanocrystal (CNC) from abaca plant is incorporated to provide the necessary toughness for 3D printable biopolymer. Hence, this work demonstrates 3D printing of CNC-filled biomaterial with significant improvement in mechanical and surface properties. These findings may potentially pave the way for an alternative option in providing innovative and cost-effective patient-specific solutions to various fields in medical industry. To the best of our knowledge, this work presents the first successful demonstration of 3D printing of CNC nanocomposite hydrogel via stereolithography (SL) forming a complex architecture with enhanced material properties potentially suited for tissue engineering.

Photoreduction of Graphene Oxide and Photochemical Synthesis of Graphene-Metal Nanoparticle Hybrids by Ketyl Radicals.

The photoreduction of graphene oxide (GO) using ketyl radicals is demonstrated for the first time. The use of photochemical reduction through ketyl radicals generated by I-2959 or (1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methyl-1-propan-1-one) is interesting because it affords spatial and temporal control of the reduction process. Graphene-metal nanoparticle hybrids of Ag, Au, and Pd were also photochemically fabricated in a one-pot procedure. Comprehensive spectroscopic and imaging techniques were carried out to fully characterize the materials. The nanoparticle hybrids showed promising action for the catalytic degradation of model environmental pollutants, namely, 4-nitrophenol, Rose Bengal, and Methyl Orange. The process described can be extended to polymer nanocomposites that can be photopatterned and could be potentially extended to fabricating plastic electronic devices.

Simultaneous Reduction and Functionalization of Graphene Oxide via Ritter Reaction.

Graphene oxide, the oxidized form of graphite, is a common precursor to conductive nanosheets and used widely in the preparation of composite materials. GO has the benefits of easy exfoliation and handling, but it tends to aggregate and restack when reduced. One approach to overcoming this undesired aggregation is covalent modification of the nanosheets; however, this typically requires additional reagents and time. Herein, we report the simultaneous reduction and functionalization of graphene oxide using the Ritter reaction such that reduced nanosheets show good conductivity without the aggregation typical of unmodified material. GO reacts with nitriles in strongly acidic conditions to give highly reduced graphene oxide (C:O of 4.38:1) with covalently attached amides, which compatibilizes it to a number of organic solvents. This Ritter-type reaction produces carbocations on the basal plane of graphene oxide, which allows nucleophilic attack by the nitrogen of the nitrile and produces amides upon hydrolysis. The product has sheet resistance (57.60 ± 4.04 kΩ/sq) substantially lower than that of the starting graphene oxide (529.60 ± 10.04 kΩ/sq) and, more importantly, can easily be dispersed in various organic solvents and does not restack into graphite-like materials upon drying. This method yields individual conductive nanosheets that can be readily incorporated into a number of different systems.

High-Strength Stereolithographic 3D Printed Nanocomposites: Graphene Oxide Metastability.

The weak thermomechanical properties of commercial 3D printing plastics have limited the technology's application mainly to rapid prototyping. In this report, we demonstrate a simple approach that takes advantage of the metastable, temperature-dependent structure of graphene oxide (GO) to enhance the mechanical properties of conventional 3D-printed resins produced by stereolithography (SLA). A commercially available SLA resin was reinforced with minimal amounts of GO nanofillers and thermally annealed at 50 and 100 °C for 12 h. Tensile tests revealed increasing strength and modulus at an annealing temperature of 100 °C, with the highest tensile strength increase recorded at 673.6% (for 1 wt % GO). Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) also showed increasing thermal stability with increasing annealing temperature. The drastic enhancement in mechanical properties, which is seen to this degree in 3D-printed samples reported in literature, is attributed to the metastable structure of GO, polymer-nanofiller cross-linking via acid-catalyzed esterification, and removal of intercalated water, thus improving filler-matrix interaction as evidenced by spectroscopy and microscopy analyses.

3D Printing Biocompatible Polyurethane/Poly(lactic acid)/Graphene Oxide Nanocomposites: Anisotropic Properties.

Blending thermoplastic polyurethane (TPU) with poly(lactic acid) (PLA) is a proven method to achieve a much more mechanically robust material, whereas the addition of graphene oxide (GO) is increasingly applied in polymer nanocomposites to tailor further their properties. On the other hand, additive manufacturing has high flexibility of structure design which can significantly expand the application of materials in many fields. This study demonstrates the fused deposition modeling (FDM) 3D printing of TPU/PLA/GO nanocomposites and its potential application as biocompatible materials. Nanocomposites are prepared by solvent-based mixing process and extruded into filaments for FDM printing. The addition of GO largely enhanced the mechanical property and thermal stability of the nanocomposites. Interestingly, we found that the mechanical response is highly dependent on printing orientation. Furthermore, the 3D printed nanocomposites exhibit good biocompatibility with NIH3T3 cells, indicating promise as biomaterials scaffold for tissue engineering applications.

Star-like copolymer stabilized noble-metal nanoparticle powders.

The amphiphilic star-like copolymer polyethylenimine-block-poly(ε-caprolactone) (PEI-b-PCL) was utilized to transfer the pre-synthesized citrate-capped noble metal nanoparticles (NMNPs) from an aqueous layer to an organic layer without any additional reagents. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) were utilized to study the assembly of the polymers coated on the surface of the citrate-capped NMNPs. After removing the organic solvent, the polymer-coated NMNPs in powder form (PCP-NMNPs) were obtained. The excellent solubility of the PEI-b-PCL allows the PCP-NMNPs to be easily dispersed in most of the organic solvents without any significant aggregation. Moreover, the good thermal stability and long-term stability make PCP-NMNPs an excellent NMNP-containing hybrid system for different specific applications, such as surface coating, catalysis and thermoplastic processing of nanocomposite materials.

Grafted carbazole-assisted electrodeposition of graphene oxide.

The electrodeposition of graphene oxide (GO) by covalently linked electroactive monomer, carbazole (Cbz) is first demonstrated herein. This is based on the electropolymerization and electrodeposition of covalently linked Cbz units when a potential is applied. During the electrochemical process, the Cbz groups electropolymerize and carry the GO nanosheets as it electrodeposits on the substrate. Moreover, the GO-Cbz sheets selectively deposit onto the conducting regions of the substrate, which demonstrates its promise for the fabrication of electropatterned graphene-based devices. In addition, GO-Cbz is a promising material for the fabrication of nanocomposite coatings for anticorrosion application. In as little as 1 wt % GO-Cbz loading, a protection efficiency as high as 95.4% was achieved.