Volume 4, Issue 2

Nanopatterning methods based on particle lithography offer generic capabilities for high-throughput fabrication with thin film materials, such as organothiol and organosilane self-assembled monolayers (SAMs), polymer films, biological samples, and nanoparticles. Combining scanning probe microscopy with sample preparation based on approaches with particle lithography produces robust test platforms for ultrasensitive surface measurements. For example, nanopatterns of octadecyltrichlorosilane (OTS) can be prepared on surfaces of Si(111) using designed protocols of particle lithography combined with steps of either vapor deposition, immersion, or contact printing. Changing the physical approaches for applying molecules to masked surfaces produces nanostructures with designed shapes and thickness. Billions of nanostructures can be prepared using strategies for particle lithography, requiring only basic steps of mixing, heating, centrifuging, and drying. Arrays of exquisitely small and regular nanopatterns can be prepared with few defects and high reproducibility. For nanopatterns prepared with SAMs, the endgroups can be designed to spatially define the interfacial selectivity for adsorption of proteins, nanoparticles, or electrolessly deposited metals. Particle lithography has become a mature technique, with broad applicability for thin film materials. Images and measurements acquired with scanning probe microscopy will be described for samples prepared using particle lithography-based approaches.

Besides the fundamental competition between the top-down and bottom-up approaches in nanotechnology, there are some basic aspects for organizing structures and functions at the molecular level. The recent challenges to the development of nanotechnology are marked by a group of general requirements: selection of suited building units, overcoming the restrictions of planar technology, shrinking of nanofabrication facilities, sustainable production and management of life cycles, organization of autonomy and communication at the nano-level, and the optimization of power consumption and energy management. Looking at the natural principles in the construction, synthesis, and function of proteins helps in understanding the principal differences between the currently applied technologies and the characteristics of biomolecular mechanisms in cells. This view allows formulating seven basic rules to meet the general requirements for future developments in molecular nanotechnology.

Curcumin (diferuloylmethane) is one of the potent, nontoxic, and major bioactive components present in turmeric. The major drawbacks of curcumin are low absorption and poor bioavailability. The present review highlights on the methods for the fabrication of curcumin nanoparticles and their applications in treatment of cancer and wound infections. Curcumin nanoparticles possess remarkable antibacterial, antiviral, and antiprotozoan activity. Hence, curcumin nanoparticle-loaded nano-gel, microemulsion, and nano-cream can be used for drug delivery.

The interaction between metal atoms and nucleobases has been a topic of high interest due to the wide scientific and technological implications. Combining density functional theory simulations with a literature overview, we achieved an exhaustive study of the ground state electronic properties of DNA/RNA nucleobases interacting with gold and silver atoms at three charge states: neutral, cationic, and anionic. We describe the nature of the stability and electronic properties in each hybrid metallic structure. In addition to the metal interacting with the five isolated nucleobases, we included their respective DNA-WC base pairs and one case with the protonated sugar-phosphate backbone. As a general trend, we discerned that the energetic ordering of isomers follows simple electrostatic rules as expected from previous studies. Also, we found that although the metal localizes almost all of the extra charge in the anionic system, a donation of charge is shared almost equally in the cationic system. Furthermore, the frontier orbitals of the cationic system tend to have more effects from the pairing and inclusion of the backbone than the anionic system. Finally, the electronic gap varies greatly among all of the considered structures and could be further used as a fingerprint when searching DNA-metal hybrid structures.

Subnanometer, atomically precise thiolate-protected gold nanoclusters represent an important advancement in our understanding of thiolate-protected gold nanoparticles and thiolate-gold chemistry. Aside from being a link between larger gold nanoparticles and small gold complexes, gold nanoclusters exhibit extraordinary molecule-like optical, electronic, and physicochemical properties that are promising for next-generation imaging agents, sensing devices, or catalysts. The success in elucidating a number of unique thiolate-gold surface and gold core structures has greatly improved our understanding of thiolate-gold nanoclusters. Nevertheless, monitoring the structural and electronic behavior of thiolate-protected gold nanoclusters in a variety of media or environments is crucial for the next step in advancing this class of nanomaterials. Not to mention, there are a number of thiolate-protected gold nanoclusters with unknown structures or compositions that could reveal important insights on application-based properties such as luminescence or catalytic activity. This review summarizes some of the recent contributions from X-ray absorption spectroscopy (XAS) studies on the intriguing bonding properties of thiolate-protected gold nanoclusters and some structural analogs. Advantages from XAS include a local structural, site- and element-specific analysis, suitable for ultra-small particle sizes (1–2 nm), along with versatile experimental conditions.