Polyetherimide/bucky gels nanocomposites with superior conductivity and thermal stability

Polyetherimide (PEI) nanocomposites comprising bucky gels of industrial-grade multiwalled carbon nanotubes (MWCNTs) and ionic liquid (IL, 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF6])) were prepared. The processing framework for this nanocomposite is simple, reproducible, and easily scalable. The strong interaction between IL and MWCNTs caused the latter to uniformly disperse in the PEI matrix while IL flowed into the gaps between the nanotubes' walls. The nanocomposite exhibited an enhanced conductivity of 2.01 × 10(4) Ω·cm volume resistivity at room temperature; the value decreased dramatically by 12 orders of magnitude, compared to pristine PEI. The IL free ions and MWCNTs networks provided excellent channels for electron transfer. PEI/bucky gels nanocomposites also showed improved thermal stability and high tensile strength. Other than having antiwear properties, this material can have numerous applications in the aerospace and electronics industries. Moreover, our work presents a "green" method toward modified nanocomposites industrial production as IL is environmentally safe and is easily recyclable.

Intracellular surface-enhanced Raman scattering (SERS) with thermally stable gold nanoflowers grown from Pt and Pd seeds

SERS provides great sensitivity at low concentrations of analytes. SERS combined with near infrared (NIR)-resonant gold nanomaterials are important candidates for theranostic agents due to their combined extinction properties and sensing abilities stemming from the deep penetration of laser light in the NIR region. Here, highly branched gold nanoflowers (GNFs) grown from Pd and Pt seeds are prepared and their SERS properties are studied. The growth was performed at 80 °C without stirring, and this high temperature growth method is assumed to provide great shape stability of sharp tips in GNFs. We found that seed size must be large enough (>30 nm in diameter) to induce the growth of those SERS-active and thermally stable GNFs. We also found that the addition of silver nitrate (AgNO3) is important to induce sharp tip growth and shape stability. Incubation with Hela cells indicates that GNFs are taken up and reside in the cytoplasm. SERS was observed in those cells incubated with 1,10-phenanthroline (Phen)-loaded GNFs.

P-glycoprotein targeted nanoscale drug carriers

Multi-drug resistance (MDR) is a trend whereby tumor cells exposed to one cytotoxic agent develop cross-resistance to a range of structurally and functionally unrelated compounds. P-glycoprotein (P-gp) efflux pump is one of the mostly studied drug carrying processes that shuttle the drugs out of tumor cells. Thus, P-gp inhibitors have attracted a lot of attention as they can stop cancer drugs from being pumped out of target cells with the consumption of ATP. Using quantitive structure activity relationship (QSAR), we have successfully synthesized a series of novel P-gp inhibitors. The obtained dihydropyrroloquinoxalines series were fully characterized and then tested against bacterial and tumor assays with over-expressed P-gps: All compounds were bioactive especially compound 1 c that had enhanced antibacterial activity. Furthermore, these compounds were utilized as targeting vectors to direct drug delivery vehicles such as silica nanoparticles (SNPs) to cancerous Hela cells with over expressed P-gps. Cell uptake studies showed a successful accumulation of these decorated SNPs in tumor cells compared to undecorated SNPs. The results obtained show that dihydropyrroloquinoxalines constitute a promising drug candidate for targeting cancers with MDR.

A tristable [2]pseudo[2]rotaxane

A strategy towards increasing the lifetime of the metastable state of a [2]rotaxane incorporating tetrathiafulvalene, 1,5-dioxynaphthalene and bipyridinium (BIPY(2+)) is presented. Incorporation of BIPY(2+) served multiple roles as an electrostatic barrier to relaxation, a supramolecular recognition site for bis-1,5-dioxynaphthalene[38]crown-10 macrocycle, and upon reduction a recognition site for the mechanically bonded cyclobis(paraquat-p-phenylene) ring.

Mechanised nanoparticles for drug delivery

Time and time again humanity is faced with a unifying global crisis that crosses the many great divides in different societies and serves to bring once segregated communities back together as a collective whole. This global community instinctively turns to science to develop the means of addressing its most pressing problems. More often than not, these forces dictate the direction that scientific research takes. This influence is no more apparent than in the field of supramolecular chemistry where, for decades now, its responsibility to tackle such issues has been put on the back burner as a consequence of a lack of platforms with which to deliver this contemporary brand of chemistry to meaningful applications. However, the tide is slowly turning as new materials emerge from the field of nanotechnology that are poised to host the many attractive attributes that are inherent in the chemistry of these supermolecules and also in the mechanostereochemistry of mechanically interlocked molecules (MIMs), which can be reused as a sequel to supramolecular chemistry. Mesoporous silica nanoparticles (SNPs) have proven to be supremely effective solid supports as their surfaces are easily functionalised with either supermolecules or MIMs. In turn, the blending of supramolecular chemistry and mechanostereochemistry with mesoporous SNPs has led to a new class of materials - namely, mechanised SNPs that are effectively biological nanoscale 'bombs' that have the potential to infiltrate cells and then, upon the pulling of a chemical trigger, explode! The development of these materials has been driven by the need to devise new therapies for the treatment of cancer. Recent progress in research promises not only to control the acuteness of this widespread and insidious disease, but also to make the harsh treatment less debilitating to patients. This global scourge is the unifying force that has brought together supramolecular chemistry, mechanostereochemistry and nanotechnology, uniting these three communities for the common good. At the nanoscale level, the mechanism for the release of cargos from the confines of the nanopores in the SNPs is accomplished by way of mechanical modifications made on the surface of these functionalised supports. These mechanical motions rely on both supramolecular, i.e., host-guest complexes, and mechanostereochemical phenomena (e.g., bistable rotaxanes), which are often stimulated by changes in pH, light and redox potentials, in addition to enzymatic catalysis. The future of this field lies in the development of 'smart bombs' wherein the loaded mechanised SNPs are endocytosed selectively by cancer cells, whereupon an intracellular trigger causes release of a cytotoxin, effectively leading to apoptosis. This review serves to highlight (1) the evolution of surface-functionalisation of SNPs with supermolecules and also with MIMs, (2) the mechanisms through which controlled-release of cargo from mechanised SNPs occurs, and (3) results from the in vitro application of these mechanised SNPs.