Transport Of Nanoparticles Research Articles

Effect of UV Irradiation on the Growth of ZnO:Er Nanorods and Their Intrinsic Defects

Nanorods of erbium-doped zinc oxide (ZnO:Er) were fabricated using a hydrothermal method. One batch was prepared with and another one without constant ultraviolet (UV) irradiation applied during the growth. The nanorods were free-standing (FS) as well as deposited onto a fused silica glass substrate (GS). The goal was to study the atomistic aspects influencing the charge transport of ZnO nanoparticles, especially considering the differences between the FS and GS samples. We focused on the excitons; the intrinsic defects, such as zinc interstitials, zinc vacancies, and related shallow donors; and the conduction electrons. UV irradiation was applied for the first time during the ZnO:Er nanorod growth. This led to almost total exciton and zinc vacancy luminescence reduction, and the number of shallow donors was strongly suppressed in the GS samples. The effect was much less pronounced in the FS rods. Moreover, the exciton emission remained unchanged there. At the same time, the Er3+ content was decreased in the FS particles grown under constant UV irradiation while Er3+ was not detected in the GS particles at all. These phenomena are explained.

Quantitative tracking of trans-synaptic nose-to-brain transport of nanoparticles and its modulation by odor, aging, and Parkinson’s disease

Quantitative tracking of trans-synaptic nose-to-brain transport of nanoparticles and its modulation by odor, aging, and Parkinson’s disease

Low intensity ultrasound-mediated drug-loaded nanoparticles intravaginal drug delivery: an effective synergistic therapy scheme for treatment of vulvovaginal candidiasis

PurposeVulvovaginal candidiasis (VVC) is a mucosal infection of the female lower genital tract for which treatment using conventional antifungal drugs shows limited effectiveness. Herein, amphotericin B-loaded poly(lactic-co-glycolic acid)-polyethylene glycol (PLGA-PEG) nanoparticles (AmB-NPs) were fabricated and combined with low intensity ultrasound (US) to mediate AmB-NPs intravaginal drug delivery to achieve productive synergistic antifungal activity in a rabbit model of VVC.MethodsPolymeric AmB-NPs were fabricated by a double emulsion method and the physical characteristics and biosafety of nanoparticles were analyzed. The distribution and tissue permeability of nanoparticles after intravaginal ultrasound irradiation (1.0 MHz, 1.0 W/cm2, 5 min, 50% duty ratio) were observed in the vagina. The synergistic therapeutic activity of US-mediated AmB-NPs treatment was evaluated using an experimental rabbit model of VVC. Vaginal C. albicans colony counts, the pathological structure of the vagina epithelium, and Th1/Th2/Th17-type cytokine and oxidative stress levels were analyzed to investigate the therapeutic effect in vivo.ResultsThe prepared AmB-NPs showed an obvious shell and core structure with uniform size and good dispersion and displayed high biosafety and US-sensitive slow drug release. Ultrasound significantly enhanced nanoparticle transport through the mucus and promoted permeability in the vaginal tissue. US-mediated AmB-NPs treatment effectively increased drug sensitivity, even in the presence of the vaginal mucus barrier in vitro. On the seventh day after treatment in vivo, the combination treatment of AmB-NPs and US significantly reduced the fungal load in the vagina, achieving over 95% clearance rates, and also improved the pathological epithelium structural damage and glycogen secretion function. The expression of Th1 (IFN-γ, IL-2) and Th17 (IL-17) cytokines were significantly increased and Th2 (IL-6, IL-10) cytokines significantly decreased in the US + AmB-NP group. Furthermore, US-mediated AmB-NPs treatment effectively increased C. albicans intracellular reactive oxygen species (ROS) levels and promoted vaginal oxidation and antioxidants to normal levels.ConclusionUS-mediated drug-loaded nanoparticles with intravaginal drug delivery exhibited a productive synergistic antifungal effect, which may provide a new non-invasive, safe, and effective therapy for acute or recurrent fungal vaginitis.Graphical

Influence of alternating magnetic field on non-newtonian blood perfusion and transport of nanoparticles in tissues with embedded blood vessel during hyperthermia

In this paper, we consider the impact of an alternating magnetic field on axisymmetric non-Newtonian nanofluid flow and nanoparticle (magnetite or iron-platinum) transport through a blood vessel and surrounding tissue during hyperthermia therapy. The geometrical domain of the problem is divided into four regions; the blood vessel region, cancerous and non-cancerous muscle or prostate regions, and a fat region. Each of the tissue regions is considered to be a saturated porous material that admits fluid flow, which is given by the Darcy-Brinkman-Forchheimer model. The Quemada model is used to describe the non-Newtonian nature of blood in each region. The resulting unsteady coupled governing equations and corresponding boundary and initial conditions are numerically solved by using the finite element method with Taylor-Hood elements. A physically realistic range of parameter values are used when numerically solving the governing equations. Using the obtained numerical solution, the effects of magnetic field amplitude and oscillation frequency, inlet nanoparticle solid volume fraction and nanoparticle diameter on nanofluid velocity, temperature, pressure and nanoparticle distribution are examined. The results determined that more heat generation is achieved with a larger volume fraction of injected nanoparticles and higher magnetic field amplitude. Also, heat generation is maximized by using nanoparticles with a diameter near 15nm and a magnetic field oscillation frequency near 4×104s-1. Thus, the present study provides an improved understanding of the factors influencing the effectiveness of intravenous magnetic hyperthermia cancer therapy in muscle and prostate tissues. The heat generated by the considered nanoparticles under an alternating magnetic field can be more accurately predicted and controlled using the two-phase non-Newtonian model of fluid flow and convective heat and mass transfer that is investigated herein.

Review on aquatic toxicity of metal oxide nanoparticles

Metal oxide nanoparticles are some of the most widely used nanomaterials in the agriculture, consumer products, and energy sectors. Their increased requirements and wide applications can necessarily cause harm to ecosystems and organisms. So, it is vital to understand the main toxicity before they caused harmful effects on the human health. The unique characteristics of nanoengineered materials include carbon fullerenes, carbon nanotubes, metal oxide nanoparticles and quantum dots, among many others have led to the capacity for various toxicities in comparison to the materials in bulk. This review mainly metal oxide nanoparticle can exert adverse effects on humans and aquatic organisms; however, their toxic mechanisms are still unclear. With the well-known consequences of inhaled fine particulate matter, inhalational toxicity is to be expected. Nanotoxicology exhibits a booming research area and aims in finding out their societal or an environmental threat. Ecological factors along with the innatequalities affect nanoparticles (NPs) fate, behavioural and transport, and eventually leading to toxicity. This review examines the research performed in the last two decade to show how metal and metal oxide nanoparticles are influencing the aquatic environment. We addressed here, the physico-chemical characteristics of nanomaterials (NMs), characterization, exposure routes in the aquatic ecosystem. This review summarizes the current understanding and the future possibilities of challenges and advances in nanotoxicology research.

Screening of Zwitterionic Liposomes with Red Blood Cell‐Hitchhiking and Tumor Cell‐Active Transporting Capability for Efficient Tumor Entrance

AbstractThe active transport of nanoparticles into the solid tumor through cell transcytosis has shown great promise in cancer nanomedicine, but it is challenging to develop efficient active transporting nanomedicines with the potential for clinical translation. Here, a type of tertiary amine oxide (TAO)‐containing zwitterionic liposomal nanocarriers is developed that can hitchhike red blood cells (RBCs) to tumor blood vessels and enter solid tumors through transcytosis. To boost the active‐transporting capability, a library of the TAO liposomes (TAOLs) with different chemical structures and particle sizes is constructed and screened by their stability and active transporting capability. Two types of TAOLs are identified that can induce efficient tumor cell transcytosis through rapid macropinocytosis and endoplasmic reticulum/Golgi‐involved exocytosis. It is found that these zwitterionic TAOLs can hitchhike RBCs to gain long blood circulation, get off the cell at the tumor site, effectively enter the tumor through transcytosis, and infiltrate the whole tumor. The chemotherapeutic drug‐loaded liposomes can stop the tumor progression of mice bearing human hepatocellular carcinoma HepG2 cells, exhibiting superior antitumor activity compared to the traditional liposomal drug. This study demonstrates a strategy to construct effective active transporting liposomal nanomedicines for efficient tumor entrance.

Optimum Volume Fraction and Inlet Temperature of an Ideal Nanoparticle for Enhanced Oil Recovery by Nanofluid Flooding in a Porous Medium

Nowadays, oil companies employ nanofluid flooding to increase oil production from oil reservoirs. Herein the present work, a multiphase flow in porous media was used to simulate oil extraction from a three-dimensional porous medium filled with oil. Interestingly, the finite element method was used to solve the nonlinear partial differential equations of continuity, energy, Darcy’s law, and the transport of nanoparticles (NPs). The proposed model used nanofluids (NFs) empirical formulas for density and viscosity on NF and oil relative permeabilities and NP transport equations. The NPs thermophysical properties have been investigated and compared with their oil recovery factor (ORF) to determine the highest ORF. Different NPs (SiO2, CuO, and Al2O3) were used as the first parameter, keeping all parameters constant. The simulation was run three times for the injected fluid using the various NPs to compare the effects on enhanced oil recovery. The second parameter, volume fraction (VF), has been modeled six times (0.5, 1, 2, 3, 4, and 5%), with all other parameters held constant. The third parameter, the injected NF inlet temperature (293.15–403.15 K), was simulated assuming that all other parameters are kept constant. The energy equation was applied to choose the inlet temperature that fits the optimum NP and VF to determine the highest ORF. Findings indicated that SiO2 shows the best ORF compared to the other NPs. Remarkably, SiO2 has the lowest density and highest thermal capacity. The optimum VF of SiO2 was 4%, increasing the ORF but reduced when the VF was higher than 4%. The ORF was improved when the viscosity and density of the oil decreased by increasing the injected inlet temperature. Furthermore, the results indicated that the highest ORF of 37% was obtained at 353.15 K when SiO2 was used at a VF of 4%. At the same time, the lowest recovery is obtained when a volume of 5% was used at 403.15 K.

Transport of hydroxyapatite nanoparticles coated with polyacrylic acid under unsaturated water flow in soil columns

ABSTRACT Phosphorus (P) nanoparticles were hypothesized to exhibit greater mobility in soils than water-soluble P (WSP) and were therefore proposed to be used as a P fertilizer. Unsaturated transport is the main pathway from the application site to plant roots. Though its importance to fertilizer efficacy, quantitative evaluation of unsaturated transport of P nanoparticles has been overlooked to date. Mobility of spherical nano-hydroxyapatite particles coated with polyacrylic acid (PAA-nHAP) suspension and WSP (a mixture of KH2PO4 and K2HPO4) was evaluated in breakthrough column experiments under unsaturated states using three soils: alkaline sand (sandy-alk), acidic sandy clay loam (sandy-ac) and clayey soils. Next, P retention was determined by total P extraction layer-by-layer from the disassembled soil columns. In all soils, PAA-nHAP exhibited faster transport compared to WSP. In the sandy-alk soil, earlier breakthrough but lower plateau of the final relative P concentration of PAA-nHAP (64.0% vs. 100% of the input P concentration) and consistent low P retention with depth after washing with 10 mM KBr solution for the two sources were observed. In the other two soils, PAA-nHAP displayed greater retention near the inlet and decreased retention with depth. In the sandy-ac soil, no WSP and low final relative concentrations of PAA-nHAP (11.6%) were transported through the soil column. The retention of PAA-nHAP was much lower than that of WSP with depth. In the clayey soil, the breakthrough (relative P concentration >1%) occurred earlier (~35 pore volumes vs. ~45 pore volumes) and the eluted P concentration increased more rapidly (~2.6 times) for PAA-nHAP compared to WSP. The difference between the two sources mainly occurred at the soil surface with higher retention of WSP. Soil properties affected the P retention capacity of the two P sources, but for all soils, P mobility was increased by changing from the common soluble fertilizers to nanoparticles. Adsorption and size exclusion effect are suggested as the major factors affecting nHAP mobility. We suggest that the nHAP transport can be improved by modifying its coating with more negative zeta-potential to decrease coagulation and adopting drip flows with short hydraulic retention time. The design of the nanoparticles needs to take into account soil properties.

Machine Learning Prediction of Nanoparticle Transport with Two-Phase Flow in Porous Media

Reservoir simulation is a time-consuming procedure that requires a deep understanding of complex fluid flow processes as well as the numerical solution of nonlinear partial differential equations. Machine learning algorithms have made significant progress in modeling flow problems in reservoir engineering. This study employs machine learning methods such as random forest, decision trees, gradient boosting regression, and artificial neural networks to forecast nanoparticle transport with the two-phase flow in porous media. Due to the shortage of data on nanoparticle transport in porous media, this work creates artificial datasets using a mathematical model. It predicts nanoparticle transport behavior using machine learning techniques, including gradient boosting regression, decision trees, random forests, and artificial neural networks. Utilizing the scikit-learn toolkit, strategies for data preprocessing, correlation, and feature importance are addressed. Furthermore, the GridSearchCV algorithm is used to optimize hyperparameter tuning. The mean absolute error, R-squared correlation, mean squared error, and root means square error are used to assess the models. The ANN model has the best performance in forecasting the transport of nanoparticles in porous media, according to the results.

Effects of soil grain size and solution chemistry on the transport of biochar nanoparticles

Biochar nanoparticles (BC-NP) have attracted significant attention because of their unique environmental behavior, some of which could potentially limit large-scale field application of biochar. Accurate prediction of the fate and transportability of BC-NP in soil matrix is the key to evaluating their environmental influence. This study investigated the effects of soil grain size and environmentally relevant solution chemistry, such as ionic strength (cation concentration, 0.1 mM–50 mM; cation type, Na+, and Ca2+), and humic acid (HA; 0–10 mg/L), on the transport behavior of BC-NP via systematic column experiments. The transportability of BC-NP in the soil-packed column decreased with decreasing soil grain size and was inversely proportional to soil clay content. At low cation concentrations (0.1–1.0 mM), a considerable proportion of BC-NP (15.95%–67.17%) penetrated the soil columns. Compared with Na+, Ca2+ inhibited the transportability of BC-NP in the soil through a charge shielding effect. With increasing HA concentration, the transportability of BC-NP increased, likely due to an enhanced repulsion force between BC-NP and soil particles. However, at a high HA concentration (10 mg/L), Ca2+ bridging reduced the transportability of BC-NP in the soil. Breakthrough curves of BC-NP were explained by the two-site kinetic retention model. The antagonistic effects of ionic strength and HA indicated that the transport behavior of BC-NP in the soil was governed by competitive effects of some environmental factors, including soil grain size, environmental solution chemistry, and natural organic matter content.

Micro- and nanoparticle transport and deposition in a realistic neonatal and infant nasal upper airway

ABSTRACT The human nasal cavity develops from birth with size anatomical changes. This study aims to evaluate the flow parameters and particle deposition parameters. Neonatal and infant nasal cavities are developed using MIMICS 21.0, and the flow is evaluated by ANSYS 2021 R2 using CFD to evaluate velocity, pressure, micro- and nanoparticle depositions under sedentary breathing conditions. Neonatal nasal valve velocity was recorded 3.5 times higher compared to the infant for 1.8 LPM and 2.7 times for 3 LPM. Neonatal vestibular depositions up to 10 µm were 6.6%, which increased to 76% for 60 µm for 1.8 LPM and increased to 21.3% for 10 µm and 79% for 60 µm for 1.8 LPM. The neonatal nasal valve showed maximum depositions of around 35% for 20 µm for both flow rates. Maximum depositions of nanoparticles are in the mid-nasal region. Infant nasal cavities deposit around 1% to 2% for nanoparticles below 20 nm for both flow rates. Neonatal overall microparticle depositions doubled with an increase in flow rate up to 10 µm. The overall deposition efficiency of nanoparticles increases 1.5 times with increasing flow rate . This study will help with the medical administration of aerosol-based medications in the patient and age-specific nasal cavity.

Optimized core-shell lanthanide nanoparticles with ultrabright Ce3+-modulated second near-infrared emission for "lighting" plants.

Second near-infrared (NIR-II, 1000-1700 nm) photon-mediated fluorescence imaging has attracted extensive interest in the field of bioimaging. However, NIR-II fluorescent nanoprobes competent for plant imaging have been rarely developed. Herein, lanthanide-doped nanoparticle (LDNP) optimal core-shell structure and ultrabright NIR-II emission were developed for "lighting" plants. The Ce3+-doped active shell coated on the NaErF4:Tm core enables dual-mode red upconversion (UC) and NIR-II downconversion (DC) emission of LDNPs upon 980 nm laser excitation. Under the optimized doping content, the intensities of red UC and NIR-II DC emission were respectively boosted by 5- and 19-fold those of the core nanoparticles, which endowed LDNPs with ideal NIR-II emissive capabilities for optical imaging of plants. Significantly, the NIR-II fluorescent signal affords much higher signal-to-noise rate than the red UC. LDNPs were modified with polyethyleneimine to enable outstanding hydrophilicty and facilitate their uptake by plants. Arabidopsis thaliana and Nicotiana benthamiana were chosen as plant models for NIR-II imaging studies. The toxic effect of LDNPs after being transported into Brassica rapa chinensis was systematically studied on mice. The NIR-II imaging strategy offers a promising method for studying the uptake and transport of nanoparticles in plants.

Effect of nanoparticles of different stiffness combined with menthol/curcumol on mechanical properties of bEnd.3 cells

This study aimed to investigate the effects of nanoparticles PLGA-NPs and mesoporous silicon nanoparticles(MSNs) of different stiffness before and after combination with menthol or curcumol on the mechanical properties of bEnd.3 cells. The particle size distributions of PLGA-NPs and MSNs were measured by Malvern particle size analyzer, and the stiffness of the two nanoparticles was quantified by atomic force microscopy(AFM). The bEnd.3 cells were cultured in vitro, and the cell surface morphology, roughness, and Young's modulus were examined to characterize the roughness and stiffness of the cell surface. The changes in the mechanical properties of the cells were observed by AFM, and the structure and expression of cytoskeletal F-actin were observed by a laser-scanning confocal microscope. The results showed that both nanoparticles had good dispersion. The particle size of PLGA-NPs was(98.77±2.04) nm, the PDI was(0.140±0.030), and Young's modulus value was(104.717±8.475) MPa. The particle size of MSNs was(97.47±3.92) nm, the PDI was(0.380±0.016), and Young's modulus value was(306.019±8.822) MPa. The stiffness of PLGA-NPs was significantly lower than that of MSNs. After bEnd.3 cells were treated by PLGA-NPs and MSNs separately, the cells showed fine pores on the cell surface, increased roughness, decreased Young's modulus, blurred and broken F-actin bands, and reduced mean gray value. Compared with PLGA-NPs alone, PLGA-NPs combined with menthol or curcumol could allow deepened and densely distributed surface pores of bEnd.3 cells, increase roughness, reduce Young's modulus, aggravate F-actin band breakage, and diminish mean gray value. Compared with MSNs alone, MSNs combined with menthol could allow deepened and densely distributed surface pores of bEnd.3 cells, increase roughness, reduce Young's modulus, aggravate F-actin band breakage, and diminish mean gray value, while no significant difference was observed in combination with curcumol. Therefore, it is inferred that the aromatic components can increase the intracellular uptake and transport of nanoparticles by altering the biomechanical properties of bEnd.3 cells.

Modulation of engineered nanomaterial interactions with organ barriers for enhanced drug transport.

The biomedical use of nanoparticles (NPs) has been the focus of intense research for over a decade. As most NPs are explored as carriers to alter the biodistribution, pharmacokinetics and bioavailability of associated drugs, the delivery of these NPs to the tissues of interest remains an important topic. To date, the majority of NP delivery studies have used tumor models as their tool of interest, and the limitations concerning tumor targeting of systemically administered NPs have been well studied. In recent years, the focus has also shifted to other organs, each presenting their own unique delivery challenges to overcome. In this review, we discuss the recent advances in leveraging NPs to overcome four major biological barriers including the lung mucus, the gastrointestinal mucus, the placental barrier, and the blood-brain barrier. We define the specific properties of these biological barriers, discuss the challenges related to NP transport across them, and provide an overview of recent advances in the field. We discuss the strengths and shortcomings of different strategies to facilitate NP transport across the barriers and highlight some key findings that can stimulate further advances in this field.

MODELING THE EFFECT OF PHYSICAL AND CHEMICAL HETEROGENEITY OF GRAIN SURFACE ON NANOPARTICLE TRANSPORT IN A SINGLE PORE IN SOIL

The physical and chemical heterogeneity of soil grains significantly affects nanoparticle transport. However, no quantitative relationships exist for particle deposition rates accounting for grain-surface heterogeneity. This study quantifies the effect of various physicochemical parameters on the nanoparticle deposition rate coefficients in a single heterogeneous pore in soil. A mathematical model is developed to simulate the transport of nanoparticles through an idealized pore of cylindrical shape with rings of the same height on the wall representing roughness. Chemical heterogeneity is considered by assigning positive and negative charges to the top of the ring elements and the remaining area of the pore wall, respectively. Particle transport is simulated by solving the advection-diffusion equation with first-order sorption at the pore wall. Nanoparticle breakthrough curves obtained from simulations are fitted with a 1D advection-dispersion-sorption equation. The pore-averaged deposition rate coefficients obtained thus are satisfactorily described using a power-law relationship vis-a-vis pore-scale parameters. The Damkohler number for nanoparticle attachment to the pore wall is significantly affected by parameters representing pore and particle radii, flow velocity, surface potentials of nanoparticles, and regions of the pore wall having positive and negative charges, and Hamaker constant. However, the Damkohler number for nanoparticle detachment from the pore wall is predominantly influenced by parameters representing particle size, roughness height, surface potentials of nanoparticles, and regions of the pore wall having positive and negative charges, Hamaker constant, and ionic strength. Chemical heterogeneity plays a dominant role in nanoparticle retention than wall roughness. The above relations can be incorporated into a pore-network model to quantify the effect of grain-surface heterogeneity on nanoparticle deposition at the continuum scale.

The Effect of Salinity on Transport and Retention of Hydroxyapatite Nanoparticles Through Saturated Porous Media

The Effect of Salinity on Transport and Retention of Hydroxyapatite Nanoparticles Through Saturated Porous Media

Ultralarge suspended and perforated graphene membranes for cell culture applications.

With its high mechanical strength and its remarkable thermal and electrical properties, suspended graphene has long been expected to find revolutionary applications in optoelectronics or as a membrane in nano-devices. However, the lack of efficient transfer and patterning processes still limits its potential. In this work, we report an optimized anthracene-based transfer process to suspend few layers of graphene (1-, 2- and 4-layers) in the millimeter range (up to 3 mm) with high reproducibility. We have explored the advantages and limitations for patterning of these membranes with micrometer-resolution by focused ion beam (FIB) and picosecond pulsed laser ablation techniques. The FIB approach offers higher patterning resolution but suffers from the low throughput. We demonstrate that cold laser ablation is a fast and flexible method for micro-structuring of suspended graphene. One promising field of application of ultimately thin, microporous graphene membranes is their use as next-generation cell culture supports as alternative to track-etched polymer membranes, which often exhibit poor permeability and limited cell-to-cell communication across the membranes. To this end, we confirmed good adhesion and high viability of placental trophoblast cells cultivated on suspended porous graphene membranes without rupturing of the membranes. Overall, there is high potential for the further development of ultrathin suspended graphene membranes for many future applications, including their use for biobarrier cell culture models to enable predictive transport and toxicity assessment of drugs, environmental pollutants, and nanoparticles.

The Heterogeneous Diffusion of Polystyrene Nanoparticles and the Effect on the Expression of Quorum-Sensing Genes and EPS Production as a Function of Particle Charge and Biofilm Age.

Biofilms are abundantly present in both natural and engineered environmental systems and will likely influence broader particle fate and transport phenomena. While some developed models describe the interactions between nanoparticles and biofilms, studies are only beginning to uncover the complexity of nanoparticle diffusion patterns. With the knowledge of the nanoparticle potential to influence bacterial processes, more systematic studies are needed to uncover the dynamics of bacteria-nanoparticle interactions. This study explored specific microbial responses to nanoparticles and the heterogeneity of nanoparticle diffusion. Pseudomonas aeruginosa biofilms (cultivated for 48 and 96 hours, representing early and late stages of development) were exposed to charged (aminated and carboxylated) polystyrene nanoparticles. With a combination of advanced fluorescence microscopy and real time quantitative PCR, we characterized the diffusion of polystyrene nanoparticles in P. aeruginosa biofilms and evaluated how biofilms respond to the presence of nanoparticles in terms of the expression of key EPS production-associated genes (pelA and rpsL) and quorum-sensing associated (lasR) genes. Our findings show that nanoparticle diffusion coefficients are independent of the particle surface charge only in mature biofilms and that the presence of nanoparticles influences bacterial gene expression. Independent of the particle's charge polystyrene nanoparticles down-regulated pelA in mature biofilms. By contrast, charge-specific responses were identified in lasR and rpsL gene expression. The targeted genes expression analysis and heterogeneous diffusion models demonstrate that particle charge influences nanoparticle mobility and provides significant insight into the intrinsic structural heterogeneity of P. aeruginosa biofilms. These findings suggest that biofilm maturity and particle charge are essential factors to consider when evaluating the transport of nanoparticles within a biofilm matrix.

Surface chemistry mediates the tumor entrance of nanoparticles probed using single-molecule dual-imaging nanodots.

The active transport of nanoparticles into solid tumors through transcytosis has been recognized as a promising way to enhance tumor accumulation and penetration, but the effect of the physicochemical properties of nanoparticles remains unclear. Herein, we develop a type of single-molecule dual imaging nanodot by divergent growth of perylenediimide (PDI)-dye-cored polylysine dendrimers and internal orthogonal conjugation of Gd(III)-based macrocyclic probes for fluorescence imaging and magnetic resonance imaging (MRI) of surface chemistry-dependent tumor entrance. The MRI and fluorescence imaging show that sixth-generation nanodots with acetylated (G6-Ac) and oligo ethylene glycol (G6-OEG) surfaces exhibit similar high tumor accumulation but different intratumor distribution. Cellular uptake and transport experiments suggest that G6-Ac nanodots have lower lysosomal entrapment (61% vs. 83%) and a higher exocytotic rate (47% vs. 29%) than G6-OEG. Therefore, G6-Ac is more likely to undergo intercellular transport through cell transcytosis, and is able to reach a tumor area distant from blood vessels, while G6-OEG mainly enters the tumor through enhanced permeability and retention (EPR) effect-based passive transport, and is not able to deliver to distant tumor areas. This study suggests that it is possible to boost the tumor entrance of nanoparticles by engineering surface chemistry for active transport.

Self-propelled continuous transport of nanoparticles on a wedge-shaped groove track.

Controlling the directional motion of nanoparticles on the surface is particularly important for human life, but achieving continuous transport is a time-consuming and demanding task. Here, a spontaneous movement of nanoflakes on a wedge-shaped groove track is demonstrated by using all-atom molecular dynamics (MD) simulations. Moreover, an optimized track, where one end of the substrate is cut into an angle, is introduced to induce a sustained directional movement. It is shown that the wedge-shaped interface results in a driving force for the nanoflakes to move from the diverging to the converging end, and the angular substrate provides an auxiliary driving force at the junction to maintain continuous transport. A force analysis is carried out in detail to reveal the driving mechanism. Moreover, the sustained transport is sensitive to the surface energy and structural characteristics of the track: the nanoflakes are more likely to move continuously on the track with lower surface energy and a smaller substrate and groove opening angle. The present findings are useful for designing nanodevices to control the movement of nanoparticles.