Enyi Ye

Recent Advances of Using Hybrid Nanocarriers in Remotely Controlled Therapeutic Delivery

The development of hybrid biomaterials has been attracting great attention in the design of materials for biomedicine. The nanosized level of inorganic and organic or even bioactive components can be combined into a single material by this approach, which has created entirely new advanced compositions with truly unique properties for drug delivery. The recent advances in using hybrid nanovehicles as remotely controlled therapeutic delivery carriers are summarized with respect to different nanostructures, including hybrid host-guest nanoconjugates, micelles, nanogels, core-shell nanoparticles, liposomes, mesoporous silica, and hollow nanoconstructions. In addition, the controlled release of guest molecules from these hybrid nanovehicles in response to various remote stimuli such as alternating magnetic field, near infrared, or ultrasound triggers is further summarized to introduce the different mechanisms of remotely triggered release behavior. Through proper chemical functionalization, the hybrid nanovehicle system can be further endowed with many new properties toward specific biomedical applications.

Polymeric Hydrogels and Nanoparticles: A Merging and Emerging Field

Hydrogels have had extensive applications in scientific and industrial applications since their invention over 50 years ago. Responsive hydrogels based on temperature, light, and pH stimuli have been developed by changing the chemical components of the matrix structure. On the other hand, metallic nanoparticles of different shapes and sizes have been prepared by physical as well as chemical methods. These inorganic assemblies are currently widely used in the biomedical sciences and engineering fields. Recently, the combined use of hydrogels and nanoparticles in a single entity has gained enormous attention in areas such as catalysts, surface-enhanced Raman scattering, biosensors, and drug delivery. In this review, recent literature describing these technologies is summarized and an outlook on the promising future of this emerging field is provided.

Effective near-infrared photodynamic therapy assisted by upconversion nanoparticles conjugated with photosensitizers

A drug model photosensitizer-conjugated upconversion nanoparticles nanocomplex was explored for application in near-infrared photodynamic therapy. As near-infrared penetrates deeper into the tissue, the model is useful for the application of photodynamic therapy in deeper tissue. The nanocomplex that was synthesized had low polydispersity, and the upconversion nanoparticle was covalently conjugated with the photosensitizer. The robust bond could prevent the undesired premature release of photosensitizer and also enhance the singlet-oxygen generation. Singlet-oxygen generation rate from this nanocomplex was evaluated in solution. The photodynamic therapy effect was assessed with MCF-7 cells in two different methods, 3-(4,5-dimethylth-iazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and live/dead assay. The assay results showed that promising efficacy (>90%) can be achieved with a low concentration (50 μg mL(-1)) of this nanocomplex and mild dosage (7 mW cm(-2)) of near-infrared laser treatment.

Plasmonic gold nanocrosses with multidirectional excitation and strong photothermal effect.

We report a facile chemical synthesis of well-defined gold nanocrosses through anisotropic growth along both <110> and <001>, whereas gold nanorods grow only along either <110> or <001>. The multiple branching was achieved by breaking the face-centered-cubic lattice symmetry of gold through copper-induced formation of single or double twins, and the resulting gold nanocrosses exhibited pronounced near-IR absorption with a great extension to the mid-IR region. As studied by discrete dipole approximation (DDA) simulations, the entire nanocross gets excited even when one of the branches is exposed to incident light. The above properties make them useful as octopus antennas for capturing near-IR light for effective photothermal destruction of cells. The cell damage process was analyzed using the Arrhenius model, and its intrinsic thermodynamic characteristics were determined quantitatively. Besides effective photothermal treatment and two-photon luminescence imaging, the near- and mid-IR-absorbing gold nanocrosses may also find applications in IR sensing, thermal imaging, telecommunications, and the like.

Recent progress of atomic layer deposition on polymeric materials

As a very promising surface coating technology, atomic layer deposition (ALD) can be used to modify the surfaces of polymeric materials for improving their functions and expanding their application areas. Polymeric materials vary in surface functional groups (number and type), surface morphology and internal structure, and thus ALD deposition conditions that typically work on a normal solid surface, usually do not work on a polymeric material surface. To date, a large variety of research has been carried out to investigate ALD deposition on various polymeric materials. This paper aims to provide an in-depth review of ALD deposition on polymeric materials and its applications. Through this review, we will provide a better understanding of surface chemistry and reaction mechanism for controlled surface modification of polymeric materials by ALD. The integrated knowledge can aid in devising an improved way in the reaction between reactant precursors and polymer functional groups/polymer backbones, which will in turn open new opportunities in processing ALD materials for better inorganic/organic film integration and potential applications.

Surface Plasmon Damping Quantified with an Electron Nanoprobe

Fabrication and synthesis of plasmonic structures is rapidly moving towards sub-nanometer accuracy in control over shape and inter-particle distance. This holds the promise for developing device components based on novel, non-classical electro-optical effects. Monochromated electron energy-loss spectroscopy (EELS) has in recent years demonstrated its value as a qualitative experimental technique in nano-optics and plasmonic due to its unprecedented spatial resolution. Here, we demonstrate that EELS can also be used quantitatively, to probe surface plasmon kinetics and damping in single nanostructures. Using this approach, we present from a large (>50) series of individual gold nanoparticles the plasmon Quality factors and the plasmon Dephasing times, as a function of energy/frequency. It is shown that the measured general trend applies to regular particle shapes (rods, spheres) as well as irregular shapes (dendritic, branched morphologies). The combination of direct sub-nanometer imaging with EELS-based plasmon damping analysis launches quantitative nanoplasmonics research into the sub-nanometer realm.

Biodegradable Thermogelling Polymers: Working Towards Clinical Applications

As society ages, aging medical problems such as organ damage or failure among senior citizens increases, raising the demand for organ repair technologies. Synthetic materials have been developed and applied in various parts of human body to meet the biomedical needs. Hydrogels, in particular, have found extensive applications as wound healing, drug delivery and controlled release, and scaffold materials in the human body. The development of the next generation of soft hydrogel biomaterials focuses on facile synthetic methods, efficacy of treatment, and tunable multi-functionalities for applications. Supramolecular 3D entities are highly attractive materials for biomedical application. They are assembled by modules via various non-covalent bonds (hydrogen bonds, p-p stacking and/or van der Waals interactions). Biodegradable thermogels are a class of such supramolecular assembled materials. Their use as soft biomaterials and their related applications are described in this Review.

Disproportionation for Growing Copper Nanowires and their Controlled Self‐Assembly Facilitated by Ligand Exchange

The coating makes the wire bundle: High-quality free-standing copper nanowires have been successfully produced by disproportionation of Cu(+) in oleylamine. This provides an effective way to prepare high-quality copper nanowires, but also enriches synthetic routes to other nanostructures. These copper nanowires can self-assemble by surface ligand exchange of oleylamine with trioctylphosphine.

Effective Targeted Photothermal Ablation of Multidrug Resistant Bacteria and Their Biofilms with NIR-Absorbing Gold Nanocrosses.

With the rapid evolution of antibiotic resistance in bacteria, antibiotic-resistant bacteria (in particular, multidrug-resistant bacteria) and their biofilms have been becoming more and more difficult to be effectively treated with conventional antibiotics. As such, there is a great demand to develop a nonantibiotic approach in efficiently eliminating such bacteria. Here, multibranched gold nanocrosses with strong near-infrared absorption falling in the biological window, which heat up quickly under near-infrared-light irradiation are presented. The gold nanocrosses are conjugated to secondary and primary antibodies for targeting PcrV, a type III secretion protein, which is uniquely expressed on the bacteria superbug, Pseudomonas aeruginosa. The conjugated gold nanocrosses are capable of completely destroying P. aeruginosa and its biofilms upon near-infrared-light irradiation for 5 min with an 800 nm laser at a low power density of ≈3.0 W cm(-2) . No bacterial activity is detected after 48 h postirradiation, which indicates that the heat generated from the irradiated plasmonic gold nanocrosses attached to bacteria is effective in eliminating and preventing the re-growth of the bacteria. Overall, the conjugated gold nanocrosses allow targeted and effective photothermal ablation of multidrug-resistant bacteria and their biofilms in the localized region with reduced nonspecific damage to normal tissue.

Near-infrared upconversion nanoparticles for bio-applications

Upconversion nanoparticles (UCNs) attract intensive attentions in biomedical applications. They have shown great potential in bioimaging, biomolecule detection, drug delivery, photodynamic therapy and cellular molecules interactions. Due to the anti-Stokes optical property and NIR excitation, UCNs overcome the drawbacks encountered in conventional luminescent biomarkers. High signal to noise ratio, low cytotoxicity and stable high throughput results are obtained using UCNs as luminescent labels or light triggers in biomedical applications. In this review article, the reason for choosing UCNs as biomedical agents, the progress of the UCNs development and case studies of their biomedical applications will be discussed.