Micromachining technology was used to prepare chemical analysis systems on glass chips (1 centimeter by 2 centimeters or larger) that utilize electroosmotic pumping to drive fluid flow and electrophoretic separation to distinguish sample components. Capillaries 1 to 10 centimeters long etched in the glass (cross section, 10 micrometers by 30 micrometers) allow for capillary electrophoresis-based separations of amino acids with up to 75,000 theoretical plates in about 15 seconds, and separations of about 600 plates can be effected within 4 seconds. Sample treatment steps within a manifold of intersecting capillaries were demonstrated for a simple sample dilution process. Manipulation of the applied voltages controlled the directions of fluid flow within the manifold. The principles demonstrated in this study can be used to develop a miniaturized system for sample handling and separation with no moving parts.

Micromachining a miniaturized capillary electrophoresis-based chemical analysis system on a chip

Photodynamic therapy (PDT) has been applied to treat a wide range of medical conditions, including wet age-related macular degeneration psoriasis, atherosclerosis, viral infection and malignant cancers. However, the tissue penetration limitation of excitation light hinders the widespread clinical use of PDT. To overcome this “Achilles' heel”, deep PDT, a novel type of phototherapy, has been developed for the efficient treatment of deep-seated diseases. Based on the different excitation sources, including near-infrared (NIR) light, X-ray radiation, and internal self-luminescence, a series of deep PDT techniques have been explored to demonstrate the advantages of deep cancer therapy over conventional PDT excited by ultraviolet-visible (UV-Vis) light. In particular, the featured applications of deep PDT, such as organelle-targeted deep PDT, hypoxic deep PDT and deep PDT-involved multimodal synergistic therapy are discussed. Finally, the future development and potential challenges of deep PDT are also elucidated for clinical translation. It is highly expected that deep PDT will be developed as a versatile, depth/oxygen-independent and minimally invasive strategy for treating a variety of malignant tumours at deep locations.

Overcoming the Achilles' heel of photodynamic therapy.

Removal of hazardous dyes-BR 12 and methyl orange using graphene oxide as an adsorbent from aqueous phase

Graphene-based materials for tissue engineering.

Research pertaining to conductive polymers has gained significant traction in recent years, and their applications range from optoelectronics to material science. For all intents and purposes, conductive polymers can be described as Nobel Prize-winning materials, given that their discoverers were awarded the Nobel Prize in Chemistry in 2000. In this review, we seek to describe the chemical forms and functionalities of the main types of conductive polymers, as well as their synthesis methods. We also present an in-depth analysis of composite conductive polymers that contain various nanomaterials such as graphene, fullerene, carbon nanotubes, and paramagnetic metal ions. Natural polymers such as collagen, chitosan, fibroin, and hydrogel that are structurally modified for them to be conductive are also briefly touched upon. Finally, we expound on the plethora of biomedical applications that harbor the potential to be revolutionized by conductive polymers, with a particular focus on tissue engineering, regene...

Conductive Polymers: Opportunities and Challenges in Biomedical Applications

Graphene oxides with different surface charges were fabricated from carboxylated graphene oxide by chemical modification with amino- (-NH2), poly-m-aminobenzene sulfonic acid- (-NH2/-SO3H), or methoxyl- (-OCH3) terminated functional groups. The chemically functionalized graphene oxides and the carboxylated graphene oxide were characterized by infrared spectroscopy, X-ray photoelectron spectroscopy, UV-Vis spectrometry, ζ potential measurements, field emission scanning electron microscopy, and contact angle analyses. Subsequently, the resulting graphene oxides were used as substrates for culturing primary rat hippocampal neurons to investigate neurite outgrowth and branching. The morphological features of neurons that directly reflect their potential capability in synaptic transmission were characterized. The results demonstrate that the chemical properties of graphene oxide can be systematically modified by attaching different functional groups that confer known characteristics to the substrate. By manipulating the charge carried by the functionalized graphene oxides, the outgrowth and branching of neuronal processes can be controlled. Compared with neutral, zwitterionic, or negatively charged graphene oxides, positively charged graphene oxide was found to be more beneficial for neurite outgrowth and branching. The ability to chemically modify graphene oxide to control neurite outgrowth could be implemented clinically, especially in cases wherein long-term presence of outgrowth modulation is necessary.

Effects of surface charges of graphene oxide on neuronal outgrowth and branching

Photodynamic therapy (PDT) is a noninvasive and light-activated method for cancer treatment. Two of the vital parameters that govern the efficiency of PDT are the light irradiation to the photosensitizer and visual detection of the selective accumulation of the photosensitizer in malignant cells. Herein, we prepared an integrated nanoplatform for targeted PDT and imaging of cancer cells using folic acid and horseradish peroxidase (HRP)-bifunctionalized semiconducting polymer dots (FH-Pdots). In the FH-Pdots, meta-tetra(hydroxyphenyl)-chlorin (m-THPC) was used as photosensitizer to produce cytotoxic reactive oxygen species (ROS); fluorescent semiconducting polymer poly[2-methoxy-5-((2-ethylhexyl)oxy)-p-phenylenevinylene] was used as light antenna and hydrophobic matrix for incorporating m-THPC, and amphiphilic Janus dendrimer was used as a surface functionalization agent to conjugate HRP and aminated folic acid onto the surface of FH-Pdots. Results indicated that the doped m-THPC can be simultaneously exci...

Small Molecule-Initiated Light-Activated Semiconducting Polymer Dots: An Integrated Nanoplatform for Targeted Photodynamic Therapy and Imaging of Cancer Cells

The presence and quantity of rare cells in the bloodstream of cancer patients provide a potentially accessible source for the early detection of invasive cancer and for monitoring the treatment of advanced diseases. The separation of rare cells from peripheral blood, as a “virtual and real-time liquid biopsy”, is expected to replace conventional tissue biopsies of metastatic tumors for therapy guidance. However, technical obstacles, similar to looking for a needle in a haystack, have hindered the broad clinical utility of this method. In this study, we developed a multistage microfluidic device for continuous label-free separation and enrichment of rare cells from blood samples based on cell size and deformability. We successfully separated tumor cells (MCF-7 and HeLa cells) and leukemic (K562) cells spiked in diluted whole blood using a unique complementary combination of inertial microfluidics and steric hindrance in a microfluidic system. The processing parameters of the inertial focusing and steric hindrance regions were optimized to achieve high-throughput and high-efficiency separation, significant advantages compared with existing rare cell isolation technologies. The results from experiments with rare cells spiked in 1% hematocrit blood indicated >90% cell recovery at a throughput of 2.24 × 107 cells min−1. The enrichment of rare cells was >2.02 × 105-fold. Thus, this microfluidic system driven by purely hydrodynamic forces has practical potential to be applied either alone or as a sample preparation platform for fundamental studies and clinical applications.

High-throughput rare cell separation from blood samples using steric hindrance and inertial microfluidics

Neurodegenerative diseases or acute injuries of the nervous system always lead to neuron loss and neurite damage. Thus, the development of effective methods to repair these damaged neurons is necessary. The construction of biomimetic materials with specific physicochemical properties is a promising solution to induce neurite sprouting and guide the regenerating nerve. Herein, we present a simple method for constructing biomimetic graphene oxide (GO) composites by covalently bonding an acetylcholine-like unit (dimethylaminoethyl methacrylate, DMAEMA) or phosphorylcholine-like unit (2-methacryloyloxyethyl phosphorylcholine, MPC) onto GO surfaces to enhance neurite sprouting and outgrowth. The resulting GO composites were characterized by Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, UV–vis spectrometry, scanning electron microscopy, and contact angle analyses. Primary rat hippocampal neurons were used to investigate nerve cell adhesion, spreading, and prolife...

Biomimetic Choline-Like Graphene Oxide Composites for Neurite Sprouting and Outgrowth

Click synthesis of quaternized poly(dimethylaminoethyl methacrylate) functionalized graphene oxide with improved antibacterial and antifouling ability.

Long Pang

Papers

Effects of surface charges of graphene oxide on neuronal outgrowth and branching

Small Molecule-Initiated Light-Activated Semiconducting Polymer Dots: An Integrated Nanoplatform for Targeted Photodynamic Therapy and Imaging of Cancer Cells

High-throughput rare cell separation from blood samples using steric hindrance and inertial microfluidics

Biomimetic Choline-Like Graphene Oxide Composites for Neurite Sprouting and Outgrowth

Click synthesis of quaternized poly(dimethylaminoethyl methacrylate) functionalized graphene oxide with improved antibacterial and antifouling ability.