There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

Rapid growth in nanotechnology is increasing the likelihood of engineered nanomaterials coming into contact with humans and the environment. Nanoparticles interacting with proteins, membranes, cells, DNA and organelles establish a series of nanoparticle/biological interfaces that depend on colloidal forces as well as dynamic biophysicochemical interactions. These interactions lead to the formation of protein coronas, particle wrapping, intracellular uptake and biocatalytic processes that could have biocompatible or bioadverse outcomes. For their part, the biomolecules may induce phase transformations, free energy releases, restructuring and dissolution at the nanomaterial surface. Probing these various interfaces allows the development of predictive relationships between structure and activity that are determined by nanomaterial properties such as size, shape, surface chemistry, roughness and surface coatings. This knowledge is important from the perspective of safe use of nanomaterials.

Understanding biophysicochemical interactions at the nano–bio interface

The interaction of nanomaterials with cells and lipid bilayers is critical in many applications such as phototherapy, imaging, and drug/gene delivery. These applications require a firm control over nanoparticle-cell interactions, which are mainly dictated by surface properties of nanoparticles. This critical Review presents an understanding of how synthetic and natural chemical moieties on the nanoparticle surface (in addition to nanoparticle shape and size) impact their interaction with lipid bilayers and cells. Challenges for undertaking a systematic study to elucidate nanoparticle-cell interactions are also discussed.

Effect of Surface Properties on Nanoparticle–Cell Interactions

50 Years of Image Analysis

Nanoscience has matured significantly during the last decade as it has transitioned from bench top science to applied technology. Presently, nanomaterials are used in a wide variety of commercial products such as electronic components, sports equipment, sun creams and biomedical applications. There are few studies of the long-term consequences of nanoparticles on human health, but governmental agencies, including the United States National Institute for Occupational Safety and Health and Japan's Ministry of Health, have recently raised the question of whether seemingly innocuous materials such as carbon-based nanotubes should be treated with the same caution afforded known carcinogens such as asbestos. Since nanomaterials are increasing a part of everyday consumer products, manufacturing processes, and medical products, it is imperative that both workers and end-users be protected from inhalation of potentially toxic NPs. It also suggests that NPs may need to be sequestered into products so that the NPs are not released into the atmosphere during the product's life or during recycling. Further, non-inhalation routes of NP absorption, including dermal and medical injectables, must be studied in order to understand possible toxic effects. Fewer studies to date have addressed whether the body can eventually eliminate nanomaterials to prevent particle build-up in tissues or organs. This critical review discusses the biophysicochemical properties of various nanomaterials with emphasis on currently available toxicology data and methodologies for evaluating nanoparticle toxicity (286 references).

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Toxicity of nanomaterials

Ultraviolet radiation (UVR) has widespread effects on the biology and integrity of the skin barrier. Research on the mechanisms that drive these changes, as well as their effect on skin barrier function, has been ongoing since the 1980s. However, no studies have examined the impact of UVR on nanoparticle skin penetration. Nanoparticles (NP) are commonly used in sunscreens and other cosmetics, and since consumer use of sunscreen is often applied to sun damaged skin, the effect of UVR on NP skin penetration is a concern due to potential toxicity. In this study, we investigate NP skin penetration by employing an in vivo semiconductor quantum dot nanoparticle (QD) model system. This model system improves NP imaging capabilities and provides additional primary interest due to widespread and expanding use of QD in research applications and manufacturing. In our experiments, carboxylated QD were applied to the skin of SKH-1 mice in a glycerol vehicle with and without UVR exposure. The skin collection and penetra...

/pdf/in-vivo-skin-penetration-of-quantum-dot-nanoparticles-in-the-p6l8katebt.pdf

In vivo skin penetration of quantum dot nanoparticles in the murine model: the effect of UVR.

Transdermal drug delivery systems have been around for decades, and current technologies (e.g., patches, ointments, and creams) enhance the skin permeation of low molecular weight, lipophilic drugs that are efficacious at low doses. The objective of current transdermal drug delivery research is to discover ways to enhance skin penetration of larger, hydrophilic drugs and macromolecules for disease treatment and vaccination. Nanocarriers made of lipids, metals, or polymers have been successfully used to increase penetration of drugs or vaccines, control drug release, and target drugs to specific areas of skin in vivo. While more research is needed to identify the safety of nanocarriers, this technology has the potential to expand the use of transdermal routes of administration to a wide array of therapeutics. Here, we review the current state of nanoparticle skin delivery systems with special emphasis on targeting skin diseases.

https://www.mdpi.com/1420-3049/21/12/1719/pdf

Nanoparticle-Enabled Transdermal Drug Delivery Systems for Enhanced Dose Control and Tissue Targeting

The dissociative chemisorption of oxygen on W(110) has been studied using molecular beam techniques. Chemisorption probabilities have been measured as a function of incidence angle, θi, and kinetic energy, Ei, and of surface coverage and temperature. In addition, angular scattering distributions have been measured for a range of conditions and LEED has been used to examine surface structure. The initial (zero coverage limit) sticking probability is found to depend strongly on the incidence energy, scaling with En=Ei cos2 θi. This probability is ∼10% at En =0.1 eV, rising to essentially unity above En =0.4 eV. At half a monolayer coverage of atomic oxygen, the sticking probability is close to zero up to a threshold of ∼0.25 eV, above which it rises to over 50% by 1.3 eV. In most cases, the sticking probability is found to fall roughly linearly with increasing surface coverage. However, a less‐than‐linear fall‐off is observed for En ≥1 eV and for En ≤0.03 eV, the sticking probability actually rises with inc...

Effect of incidence kinetic energy and surface coverage on the dissociative chemisorption of oxygen on W(110)

https://www.jidonline.org/article/S0022-202X(15)35614-1/pdf

Applications of Nanotechnology in Dermatology

Porous silicon multilayer structures have remarkable optical and morphological properties that can be exploited for biosensing In particular, a high internal surface area (>100 m(2)/cm(3)) and a linear response profile to changes in the dielectric environment enable fabrication of sensitive devices and a straightforward quantitation of the optical response These essential operating characteristics are illustrated for p+ mesoporous silicon (pore diameter 15-20 nm) optical microcavities A series of devices were prepared to permit the immobilization of glutathione-S-transferase ( approximately 50 kDa) within the porous matrix Enzyme activity was exploited as an indirect means to quantitate the amount of protein immobilized Activity was positively correlated with the optical sensor response However, at high enzyme load the activity becomes nonlinear while the microcavity response remains linear These data were used to determine the transduction limit (minimum amount of protein required to transduce an optical response), which is reported as areal mass sensitivity ranging between 50 and 250 pg/mm(2) This value is considered in context with the dynamic range of the bulk sensitivity, defined as the magnitude of the wavelength shift per refractive index unit, which was measured as a function of microcavity design parameters This work has uncovered key parameters that can be tuned to improve the detection limit of this sensor modality Because of the ever increasing number of emerging new biosensor technologies, defining sensor detection limits has become an ambiguous topic and a need exists to standardize measurements and sensitivity units For chip-based devices, it seems appropriate to report sensitivity in terms of the minimum number of grams of bound target per surface area

Lisa A. DeLouise

Papers

In vivo skin penetration of quantum dot nanoparticles in the murine model: the effect of UVR.

Nanoparticle-Enabled Transdermal Drug Delivery Systems for Enhanced Dose Control and Tissue Targeting

Effect of incidence kinetic energy and surface coverage on the dissociative chemisorption of oxygen on W(110)

Applications of Nanotechnology in Dermatology

Cross-Correlation of Optical Microcavity Biosensor Response with Immobilized Enzyme Activity. Insights into Biosensor Sensitivity