Enhanced cellular uptake of size-separated lipophilic silicon nanoparticles

Nanotherapeutic Heterogeneity: Sources, Effects, and Solutions

Nanomaterials have revolutionized medicine by enabling control over drugs' pharmacokinetics, biodistribution, and biocompatibility. However, most nanotherapeutic batches are highly heterogeneous, meaning they comprise nanoparticles that vary in size, shape, charge, composition, and ligand functionalization. Similarly, individual nanotherapeutics often have heterogeneously distributed components, ligands, and charges. This review discusses nanotherapeutic heterogeneity's sources and effects on experimental readouts and therapeutic efficacy. Among other topics, it demonstrates that heterogeneity exists in nearly all nanotherapeutic types, examines how nanotherapeutic heterogeneity arises, and discusses how heterogeneity impacts nanomaterials' in vitro and in vivo behavior. How nanotherapeutic heterogeneity skews experimental readouts and complicates their optimization and clinical translation is also shown. Lastly, strategies for limiting nanotherapeutic heterogeneity are reviewed and recommendations for developing more reproducible and effective nanotherapeutics provided.

Interaction of 2D nanomaterial with cellular barrier: Membrane attachment and intracellular trafficking

The cell membrane serves as a barrier against the free entry of foreign substances into the cell. Limited by factors such as solubility and targeting, it is difficult for some drugs to pass through the cell membrane barrier and exert the expected therapeutic effect. Two-dimensional nanomaterial (2D NM) has the advantages of high drug loading capacity, flexible modification, and multimodal combination therapy, making them a novel drug delivery vehicle for drug membrane attachment and intracellular transport. By modulating the surface properties of nanocarriers, it is capable of carrying drugs to break through the cell membrane barrier and achieve precise treatment. In this review, we review the classification of various common 2D NMs, the primary parameters affecting their adhesion to cell membranes, and the uptake mechanisms of intracellular transport. Furthermore, we discuss the therapeutic potential of 2D NMs for several major disorders. We anticipate this review will deepen researchers' understanding of the interaction of 2D NM drug carriers with cell membrane barriers, and provide insights for the subsequent development of novel intelligent nanomaterials capable of intracellular transport.

Flowing through Gastrointestinal Barriers with Model Nanoparticles: From Complex Fluids to Model Human Intestinal Epithelium Permeation

Most nanomaterial-based medicines are intravenously applied since oral administration comprises challenging-related biological obstacles, such as interactions with distinct digestive fluids and their transport through the intestinal barrier. Moreover, there is a lack of nanoparticle-based studies that faithfully consider the above-cited obstacles and boost oral-administered nanomedicines' rational design. In this study, the physicochemical stability of fluorescent model silica nanoparticles (f-SiO₂NPs) passing through all simulated gastrointestinal fluids (salivary, gastric, and intestinal) and their absorption and transport across a model human intestinal epithelium barrier are investigated. An aggregation/disaggregation f-SiO₂NPs process is identified, although these particles remain chemically and physically stable after exposure to digestive fluids. Further, fine imaging of f-SiO₂NPs through the absorption and transport across the human intestinal epithelium indicates that nanoparticle transport is time-dependent. The above-presented protocol shows tremendous potential for deciphering fundamental gastrointestinal nanoparticles' evolution and can contribute to rational oral administration-based nanomedicine design.

"Trojan Horse" Type Internalization Increases the Bioavailability of Mercury Sulfide Nanoparticles and Methylation after Intracellular Dissolution

Mercury sulfide nanoparticles (HgS_NP), as natural metal-containing nanoparticles, are the dominant Hg species in anoxic zones. Although the microbial Hg methylation of HgS_NP has been previously reported, the importance of this process in Hg methylation has yet to be clarified due to the lack of knowledge on the internalization and transformation of HgS_NP. Here, we investigated the internalization and transformation of HgS_NP in microbial methylator Geobacter sulfurreducens PCA through total Hg analysis and different Hg species quantification in medium and cytoplasm. We found that the microbial uptake of HgS_NP, via a passive diffusion pathway, was significantly higher than that of the Hg²⁺-dissolved organic matter (Hg²⁺-DOM) complex. Internalized HgS_NP were dissolved to Hg²⁺ in cytoplasm with a maximal dissolution of 41%, suggesting a "Trojan horse" mechanism. The intracellular Hg²⁺ from HgS_NP exposure at the initial stage (8 h) was higher than that in Hg²⁺-DOM group, which led to higher methylation of HgS_NP. Furthermore, no differences in methylmercury (MeHg) production from HgS_NP were observed between the hgcAB gene knockout (ΔhgcAB) and wild-type strains, suggesting that HgS_NP methylation may occur through HgcAB-independent pathways. Considering the possibility of a broad range of hgcAB-lacking microbes serving as methylators for HgS_NP and the ubiquity of HgS_NP in anoxic environments, this study highlights the importance of HgS_NP internalization and methylation in MeHg production and demonstrates the necessity of understanding the assimilation and transformation of nutrient and toxic metal nanoparticles in general.

Odor Discrimination by Lipid Membranes

Odor detection and discrimination in mammals is known to be initiated by membrane-bound G-protein-coupled receptors (GPCRs). The role that the lipid membrane may play in odor discrimination, however, is less well understood. Here, we used model membrane systems to test the hypothesis that phospholipid bilayer membranes may be capable of odor discrimination. The effect of S-carvone, R-carvone, and racemic lilial on the model membrane systems was investigated. The odorants were found to affect the fluidity of supported lipid bilayers as measured by fluorescence recovery after photobleaching (FRAP). The effect of odorants on surface-supported lipid multilayer microarrays of different dimensions was also investigated. The lipid multilayer micro- and nanostructure was highly sensitive to exposure to these odorants. Fluorescently-labeled lipid multilayer droplets of 5-micron diameter were more responsive to these odorants than ethanol controls. Arrays of lipid multilayer diffraction gratings distinguished S-carvone from R-carvone in an artificial nose assay. Our results suggest that lipid bilayer membranes may play a role in odorant discrimination and molecular recognition in general.

Impact of macroporous silica nanoparticles at sub-50nm on bio-behaviors and biosafety in drug-resistant cancer models

The in vivo bio-behaviors and biosafety of nanoparticles were demonstrated to be closely correlated with particle sizes, which illustrated whether they could be used as the effective drug delivery carriers. Though tumor penetration capabilities of the small pore sized-mesoporous silica nanoparticles (MSNs) were reported to be in a particle size-dependent manner, the size effects of large pore sized-MSNs on the safe and effective cancer resistance treatment, especially at sub-50 nm, were not explicitly evaluated. In this study, we fabricate the 20 nm and 50 nm MSNs, and aim at investigating their difference in tumor accumulation, penetration, retention and toxicity both in vitro and in vivo. Our results showed that these two particle sized-MSNs possessed the excellent tumor penetration capabilities both in resistant human hepatocellular carcinoma cells-cultured spheroids and in the corresponding xenograft mice models, but the 50 nm MSNs seemed to have the better tumor accumulation and retention effects than the 20 nm MSNs. Moreover, the 50 nm MSNs displayed the lower toxicities than the 20 nm MSNs whatever on resistant cancer cell lines or on zebrafish embryos, indicating the greater systematic biosafety. In a word, our data provide the evidence that selection of the large pore-sized MSNs at the appropriate particle size (not the smaller the better) as bio-macromolecule nanocarriers will play a key role in the safe and effective treatment against cancer resistance.

Introductory lecture: origins and applications of efficient visible photoluminescence from silicon-based nanostructures

This review highlights many spectroscopy-based studies and selected phenomenological studies of silicon-based nanostructures that provide insight into their likely PL mechanisms, and also covers six application areas.

Multiplex Photoluminescent Silicon Nanoprobe for Diagnostic Bioimaging and Intracellular Analysis

Herein, a label-free multiplex photoluminescent silicon nanoprobe (PLSN-probe) is introduced as a potential substitute for quantum dots (QDs) in bioimaging. An inherently non-photoluminescent silicon substrate is altered to create the PLSN-probe, to overcome the major drawbacks of presently available QDs. Additionally, crystallinity alterations of the multiplane crystalline PLSN-probes lead to broad absorption and multiplex fluorescence emissions, which are attributed to the simultaneous existence of multiple crystal planes. The PLSN-probe not only demonstrates unique optical properties that can be exploited for bioimaging but also exhibits cell-selective uptake that allows the differentiation and diagnosis of HeLa and fibroblast cells. Moreover, multiplex emissions of the PLSN-probe illuminate different organelles such as the nucleus, nucleolemma, and cytoskeleton, depending on size-based preferential uptake by the cell organs. This in vitro study reveals that cancerous HeLa cells have a higher propensity for taking up the PLSN-probe compared to fibroblast cells, allowing the diagnosis of cancerous HeLa cells. Additionally, the fluorescence intensity per unit area of the cell is found to be a reliable means for distinguishing between dead and healthy cells. It is anticipated that the multifunctionality of the PLSN-probes will lead to better insight into the use of such probes for bioimaging and diagnosis applications.