Ming Su

Covert thermal barcodes based on phase change nanoparticles

An unmet need is to develop covert barcodes that can be used to track-trace objects, and authenticate documents. This paper describes a new nanoparticle-based covert barcode system, in which a selected panel of solid-to-liquid phase change nanoparticles with discrete and sharp melting peaks is added in a variety of objects such as explosive derivative, drug, polymer, and ink. This method has high labeling capacity owing to the small sizes of nanoparticles, sharp melting peaks, and large scan range of thermal analysis. The thermal barcode can enhance forensic investigation by its technical readiness, structural covertness, and robustness.

Reducing X-Ray Induced Oxidative Damages in Fibroblasts with Graphene Oxide

A major issue of X-ray radiation therapy is that normal cells can be damaged, limiting the amount of X-rays that can be safely delivered to a tumor. This paper describes a new method based on graphene oxide (GO) to protect normal cells from oxidative damage by removing free radicals generated by X-ray radiation using grapheme oxide (GO). A variety of techniques such as cytotoxicity, genotoxicity, oxidative assay, apoptosis, γ-H2AX expression, and micro-nucleus assay have been used to assess the protective effect of GO in cultured fibroblast cells. It is found that although GO at higher concentration (100 and 500 µg/mL) can cause cell death and DNA damage, it can effectively remove oxygen free radicals at a lower concentration of 10 µg/mL. The level of DNA damage and cell death is reduced by 48%, and 39%, respectively. Thus, low concentration GO can be used as an effective radio-protective agent in occupational and therapeutic settings.

Enhanced Radiation Therapy with Multilayer Microdisks Containing Radiosensitizing Gold Nanoparticles

A challenge of X-ray radiation therapy is that high dose X-rays at therapeutic conditions damage normal cells. This paper describes the use of gold nanoparticle-loaded multilayer microdisks to enhance X-ray radiation therapy, where each microdisk contains over 10(5) radiosensitizing nanoparticles. The microdisks are attached on cell membranes through electrostatic interaction. Upon X-ray irradiation, more photoelectrons and Auger electrons are generated in the vicinity of the nanoparticles, which cause water ionization and lead to the formation of free radicals that damage the DNA of adjacent cancer cells. By attaching a large amount of gold nanoparticles on cancer cells, the total X-ray dose required for DNA damage and cell killing can be reduced. Due to their controllable structure and composition, multilayer microdisks can be a viable choice for enhanced radiation therapy with nanoparticles.

Printed Multilayer Microtaggants with Phase Change Nanoparticles for Enhanced Labeling Security

There is an urgent need to develop taggants that can be used to identify objects, prevent fraud, and deter counterfeiting with high reliability, high capacity, and minimal effort. This paper describes a new multilayer covert taggant based on phase change nanoparticles (metals and eutectic alloys). A panel of selected nanoparticles with different melting temperatures have been added in matrix materials together with fluorescent dye and printed on substrates to form micro-/macrofeatures that contain thermal, fluorescence signature, and structural components. The multilayer taggants can greatly enhance security level for many commercial and forensic applications by their extremely large labeling capacity, coding readiness, and covertness.

Nanomaterials for Biosensing Applications

Nanomaterials have shown tremendous potentials to impact the broad field of biological sensing. Nanomaterials, with extremely small sizes and appropriate surface modifications, allow intimate interaction with target biomolecules. [...].

Tumor targeted, stealthy and degradable bismuth nanoparticles for enhanced X-ray radiation therapy of breast cancer

Nanoparticles of heavy elements can be used as radiosensitizers to enhance X-ray radiation therapy, but a major roadblock in translating nanoparticle radiosensitizers into clinical practice of cancer treatment is related to the non-degradable nature of the nanoparticles, which can cause accumulation inside body and long-term toxicity. This paper reports the use of a folate-inserted, red blood cell membrane-modified bismuth (i.e., F-RBC bismuth) nanoparticles in X-ray radiation therapy for breast cancer, where cell membrane coating provides long blood circulation time, folate acts as tumor targeting agent, X-ray and bismuth nanoparticles interaction generates more free radicals for cancer cells damage, and physiological condition helps dissolve bismuth nanoparticles after treatment. Significant tumor inhibition and improved survival ratio in mice was confirmed when F-RBC bismuth nanoparticles were used to sensitize X-ray radiation. Inxa0vivo bio-distribution and histological analysis indicated F-RBC bismuth nanoparticles were excreted from animal body after 15 days and no evident damage or inflammatory was observed in major organs. Cell membrane modification and dissolution of bismuth nanoparticles in body allow the fine tune of the circulation, radiation enhancement and body clearance in such a way that treatment effect can be maximized and long term toxicity can be minimized.

Mechanical and Morphological Analysis of Cancer Cells on Nanostructured Substrates.

Cancer metastasis is a major cause of cancer-induced deaths in patients. Mimicking nanostructures of an extracellular matrix surrounding cancer cells can provide useful clues for metastasis. This paper compares the morphology, proliferation, spreading, and stiffness of highly aggressive glioblastoma multiforme cancer cells and normal fibroblast cells seeded on a variety of ordered polymeric nanostructures (nanopillars and nanochannels). Both cell lines survive and proliferate on the nanostructured surface and show more similarity on nanostructured surfaces than on flat surfaces. Although both show similar stiffness on the nanochannel surface, glioblastomas are softer, spread to a larger area, and elongate less than fibroblasts. The nanostructured surfaces are useful for in vitro model of an extracellular matrix to study the cancer cell migratory phenotype.

3D ordered assemblies of semiconductive micro/nanowires using microscale fibrous building blocks.

Three-dimensional (3D) ordered assemblies of semiconductive micro/nanowires are made by match-stick assembly of fibrous building blocks (FBBs). A glass tube filled with powders of starting material is processed drawn into centimeter-long, micrometer-diameter FBBs with controlled diameter and spacing. By repeating a draw-cut-stack process, the diameter and spacing of filling material can be programmably reduced from millimeters to hundreds of nanometers. The FBBs are densely packed into 3D ordered structures such that wires in one layer are at defined angle (theta) relative to those in the adjacent layers, where theta is between 0 and 180 degrees. The electrical measurements at bundled wires and single wire level confirm semiconducting behavior of wires. By directly manipulating microscale FBBs, the method allows high yield production of 3D ordered micro/nanowires with controlled position and orientation, enabling the construction of a new class of micro/nanomaterials.

Electrically Modulated Localized Surface Plasmon around Self-Assembled-Monolayer-Covered Nanoparticles

This article reports the observation of electrical modulation of localized surface plasmon around self-assembled monolayer (SAM)-modified gold nanoparticles and the establishment of a new spectroscopy technique, that is, dynamic electro-optical spectroscopy (DEOS). The gold nanoparticles are deposited onto a transparent conductive substrate, and an electrical bias applied on the conductive substrate can cause shift of resonance plasmon response, where the direction of peak shift is related to the polarity of applied bias. The peak shift observed at 2.4 V is approximately ten times larger than those reported in previous work. It is postulated that significant peak shift is the result of reorientation of adsorbed water on electrode, which can change local dielectric environment of nanoparticles. An energy barrier is identified when adsorbed water molecules are turned from oxygen-down to oxygen-up. Frequency-dependent peak shifts on surface-modified gold nanoparticles show that reorientation is a fast reversible process with rich dynamics.

Organic Phase Change Nanoparticles for in-Product Labeling of Agrochemicals

There is an urgent need to develop in-product covert barcodes for anti-counterfeiting of agrochemicals. This paper reports a new organic nanoparticle-based in-product barcode system, in which a panel of organic phase change nanoparticles is added as a barcode into in a variety of chemicals (herein agrochemicals). The barcode is readout by detecting melting peaks of organic nanoparticles using differential scanning calorimetry. This method has high labeling capacity due to small sizes of nanoparticles, sharp melting peaks, and large scan range of thermal analysis. The in-product barcode can be effectively used to protect agrochemical products from being counterfeited due to its large coding capacity, technical readiness, covertness, and robustness.