ABSTRACT
Determining whether and to what extent the relative abundance of heavy minerals in original detrital assemblage has been modified by mechanical transport is beneficial for understanding regional historical climate changes and acquiring modern sediment provenance information. Utilizing the frequency of surface mechanical optical textures of heavy minerals may be an effective approach to address this question. However, the connection between the frequency surface mechanical optical textures of heavy minerals and the variations in the relative abundance of these minerals remains uncertain. In this study, 12 modern aeolian sand samples were collected from the Badain Jaran Desert in hyper arid region of northwestern China, characterized by weak weathering to analyze their relative contents of five major heavy minerals. Then, 3796 transparent heavy mineral grains were photographed under the parallel light of a polarizing microscope, and the frequency of 13 surface mechanical optical textures were calculated. The results reveal that the variations in the relative abundance of heavy minerals are substantially influenced by mechanical transport. The decrease in the relative abundance of heavy minerals with weak mechanical stability primarily attributed to mechanical collision. Conversely, the variations in the relative abundance of heavy minerals with strong mechanical stability are primarily influenced by mechanical abrasion. Therefore, mechanical transport impact on the relative abundance of heavy minerals in regions with weak chemical weathering. Establishing heavy mineral characteristic indices for provenance studies using the relative abundance of mechanically unstable minerals may not directly indicate transport distance but rather the strength of wind forces, which have significant potential in palaeo wind regime studies. This study expands the research field of sediment surface micromorphology and has potential applications in inferring past climate changes and determining modern sediment provenance.
ABSTRACT
The porous nature and structural variability of covalent organic frameworks (COFs) make them preferred for drug loading and delivery applications. However, most COF materials suffer from poor luminescent properties and inefficiency for cell uptake. Herein, we experimentally demonstrate the crucial role of long alkoxy chains in the synthesis of crystalline COF nanostructures with high cellular uptake efficiency. After luminescence integration through band engineering, the semiconducting COF exhibits an optical bandgap of 2.05 eV, an emission wavelength of 632 nm, a high quantum yield of 37 %, and excellent fluorescence stability (100 % at 3 h). Such excellent optical properties of the designed COF nanocarriers enable quantitative evaluations of cellular uptake and visual tracking of drug delivery. It was demonstrated that the cellular uptake efficiency was enhanced by orders of magnitude for the COF after the introduction of long n-octyloxy chains, which firstly delivered the anticancer camptothecin (CPT) to cell lysosomes, and then underwent "endo/lysosomal escape" to induce cell apoptosis. In vivo assay evidenced a significant enhancement in the therapeutic effect with a 96 % inhibition of tumor growth after 14 days of treatment. This progress sheds light on designing cutting-edge drug delivery nanosystems based on COF materials with integrated diagnostic and therapeutic functions.
Subject(s)
Luminescence , Lysosomes , Crystallization , Biological Transport , ApoptosisABSTRACT
Developing smart drug delivery systems has become a feasible solution to overcome the challenges in cancer chemotherapeutics. In this work, porous boron carbon nitride (ZBCN) nanomaterials with flower-like structures assembled with BCN nanosheets were synthesized by using ZIF-L as a template. The rich hydroxyl groups on the BCN surfaces make it highly dispersible and stable in aqueous solutions. Additionally, ZBCN exhibits stable photoluminescence properties that can be utilized for cellular uptake and tracking of drug delivery. Furthermore, the flower-like ZBCN structure contributes to a large specific surface area of up to 340 m2 g-1 and a pore volume of 1.03 cm3 g-1; and the presence of rich macropores results in a high drug loading capacity of 116 wt% for paclitaxel. In vitro and in vivo anticancer experiments demonstrated that ZBCN exhibits excellent performance in delivering anticancer drugs, with in vivo tumor inhibition of 58%. This study presents a novel template method for preparing porous BCN nanomaterials, offering a promising platform for high-performance anticancer drug delivery.
ABSTRACT
Lysosomes are of great significance to cell growth, metabolism, and survival, as they independently maintain acidity and regulate various balances in cells. Therefore, it is essential to develop advanced probes for lysosome visualization and live tracking. Herein, a type of lysosome-targeting probe based on boron (B) and nitrogen (N) co-doped carbon quantum dots (B/N-CQDs) is presented, which exhibits red emission at 618 nm, high quantum yield (28%), and excellent fluorescence stability (97% at 1 h). These B/N-CQDs are prepared by a novel and green solid-state reaction and purified using a simple extraction process without additional chemical modifications. It is found that the boron dopants in the structure play a crucial role in the resultant lysosome-specific targeting property through borate esterification between boronic acid groups in the sample and diol structures in glycoproteins. This can be applied as a powerful tool for cell apoptosis, necrosis, and endosomal escape tracking. This work not only offers a new concept for targeted subcellular probe designs via chemical doping but also demonstrates the feasibility of these tools for analyzing complex cellular physiological activities.
