Large planetary seedlings, comets, microscale pharmaceuticals, and nanoscale soot particles are made from rigid, aggregated subunits that are compacted under low compression into larger structures spanning over 10 orders of magnitude in dimensional space. Here, we demonstrate that the packing density (θ f ) of compacted rigid aggregates is independent of spatial scale for systems under weak compaction. The θ f of rigid aggregated structures across six orders of magnitude were measured using nanoscale spherical soot aerosol composed of aggregates with ∼17-nm monomeric subunits and aggregates made from uniform monomeric 6-mm spherical subunits at the macroscale. We find θ f = 0.36 ± 0.02 at both dimensions. These values are remarkably similar to θ f observed for comet nuclei and measured values of other rigid aggregated systems across a wide variety of spatial and formative conditions. We present a packing model that incorporates the aggregate morphology and show that θ f is independent of both monomer and aggregate size. These observations suggest that the θ f of rigid aggregates subject to weak compaction forces is independent of spatial dimension across varied formative conditions. M any systems are comprised of elementary subunits packed within a defined volume. The simplest 3D system consists of uniform spheres, and despite its apparent simplicity, a rigorous mathematical description eluded researchers for nearly four centuries dating back to Kepler's conjecture in 1611. In 2005, Hales provided a definitive mathematical proof confirming the observed experimental maximum packing density of 74% (1). Packing of more complex structures is far more mathematically challenging and instead relies on empirical studies (2-9). One of the most ubiquitous packing systems in the universe are rigid aggregates composed of a collection of monomeric units joined together into a fractal structure and subsequently densified through omnidirectional applied force, as shown in Fig. 1 (10).The formation and compaction mechanism of disordered aggregates is presumed to be independent of dimension, composition, and spatial scale, and has been observed in a diverse range of materials and conditions, such as the accretion of material in interstellar space and the formation and compaction of aerosol in the Earth's atmosphere. Many interstellar formations comprise nano-or microscale dust particles that begin as disordered monomeric subunits, which electrostatically aggregate to form fractal (lacey) agglomerates that serve as foundries for comets and planetary seedlings (10-16). Soot, ubiquitous in the Earth's troposphere, is also comprised of nanometer sized carbonaceous monomers aggregated in a disordered lacey structure. Compaction into spheres occurs after trace gas and/or liquid adsorption and evaporation. In both cases, the resulting structure is constrained by aggregate rigidity (17).The systems described above are similarly constructed from single-unit building blocks assembled into larger disordered structures. The final structure ...

Cyclic phosphonium anhydrides generated from bis-phosphine oxides and trifluoromethanesulfonic anhydride are shown as general coupling reagents in a dehydrative glycosylation reaction of C1-hemiacetals. This reaction protocol is characterized by a broad substrate scope and high yields, including reactions of O-, C-, N-, and S-based nucleophiles with furanose, pyranose, and deoxysugar donors.

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The synthesis of a novel poly(propyleneimine) (PPI) dendron in gram scale as well as its use in the formation of a highly stable, dendronized gold nanoparticle (AuNP)-based drug delivery platform is described herein. The AuNP-based platform is composed of three complementary parts: (i) a 15 nm AuNP core, (ii) a heterofunctional thioctic acid-terminated tetraethylene glycol spacer, and (iii) a third-generation PPI dendron with a unique protonation profile and diverse end-group functionalization that allows for further derivatization. The prepared dendronized AuNPs are able to withstand several rounds of lyophilization cycles with no sign of aggregation, are stable in phosphate-buffered saline and Hanks' buffer as well as in serum, and are resistant to degradation *

Dendronized nanoparticles, also called nanoparticle-cored dendrimers, combine the advantages of nanoparticles and dendrimers. These very stable and polyvalent nanoparticles can be used for diverse applications. One such application is drug delivery, because the dendrons can enhance the density of the payload. In this report, we describe the design of multifunctional gold nanoparticles (AuNPs) coated with poly(propylene imine) (PPI) dendrons that contain both prostate cancer active targeting and chemotherapeutic drugs. The PPI dendron is a good candidate for the design of drug delivery vehicles because of its ability to induce a proton sponge effect that will enhance lysosomal escape and intracellular therapeutic delivery. The chemotherapeutic drug used is doxorubicin (DOX), and it was linked to the dendron through a hydrazone acid-sensitive bond. Subsequent acidification of the AuNP system to a pH of 4–5 resulted in the release of 140 DOX drugs per nanoparticles. In addition, the PPI dendron was conjugated via “click” chemistry to an EphA2-targeting antibody fragment that has been shown to target prostate cancer cells. In vitro cell viability assays revealed an IC50 of 0.9 nM for the targeted DOX-bearing AuNPs after 48 h incubation with PC3 cells. These results are very promising upon optimization of the system.

This work discusses in vivo experiments that were performed to evaluate whether local or whole-body heating to 40 °C reduced interstitial fluid pressures (IFPs) and enhanced nanoparticle delivery to subcutaneous PC3 human prostate cancer xenograft tumors in mice. After heating, 0.2 mL of a previously developed nanofluid containing gold nanoparticles (10 mg Au/mL) was injected via the tail vein. The induced whole-body hyperthermia led to increases in tumor and mouse body blood perfusion rates of more than 50% and 25%, respectively, while the increases were much smaller in the local heating group. In the whole-body hyperthermia groups, the IFP reduction from the baseline at the tumor center immediately after heating was found to be statistically significant when compared to the control group. The 1 h of local heating group showed IFP reductions at the tumor center, while the IFPs increased in the periphery of the tumor. The intratumoral gold nanoparticle accumulation was quantified using inductively coupled plasma mass spectrometry (ICP-MS). Compared to the control group, 1 h or 4 h of experiencing whole-body hyperthermia resulted in an average increase of 51% or 67% in the gold deposition in tumors, respectively. In the 1 h of local heating group, the increase in the gold deposition was 34%. Our results suggest that 1 h of mild whole-body hyperthermia may be a cost-effective and readily implementable strategy for facilitating nanoparticle delivery to PC3 tumors in mice.

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