Passive Uptake Research Articles

In vitro investigation of hyaluronan-based polymeric micelles for drug delivery into the skin: The internalization pathway

In our previous research, we concluded that polymeric micelles based on hyaluronic acid are able to penetrate into the deeper layers of skin tissue. The aim of this work was to characterize the mechanisms involved in the uptake by skin cells, which is important for understanding the influence of the carrier composition on the drug penetration.To reach this goal, we used micelles encapsulating curcumin made of oleyl-hyaluronan (HAC18:1) and hexyl-hyaluronan (HAC6) covalently linked with fluorescent Nile Blue. This labeling enabled us to track the micelle-forming derivative and also micelle payload into the keratinocytes and fibroblasts by fluorescent microscopy and flow cytometry. The regulation of both the passive and active cellular uptake was used to determine the mechanism of micelle internalization. Furthermore, the changes of membrane fluidity were measured for these derivatives by FRAP. Using these methods we concluded that carriers entered the cells using both active and passive transport. Passive transport was facilitated by the affinity of the carrier to the cell membrane, especially in the case of HAC18:1 carrier, which changed significantly the membrane fluidity. The active transport was dependent on cell type, but mainly driven by the clathrin-mediated endocytosis and macropinocytosis. Surprisingly, the main HA receptor, CD44, was not involved in the uptake. We can conclude that these carrier systems could be used for the local transport of active substances or hydrophobic drugs into the skin cells using the advantage of passive transport of oleyl-HA derivative.

Development and Optimization of an Airborne Formaldehyde Microfluidic Analytical Device Based on Passive Uptake through a Microporous Tube.

This paper describes a compact microfluidic analytical device developed for the detection of low airborne formaldehyde concentrations. This microdevice was based on a three-step analysis, i.e., the passive gaseous formaldehyde uptake using a microporous membrane into an acetylacetone solution, the derivatization with acetylacetone to form 3,5-diacetyl-1,4-dihydrolutidine, and the quantification of the latter using fluorescence detection. For a rapid and easier implementation, a cylindrical geometry of the microporous element was considered to perform laboratory-controlled experiments with known formaldehyde concentrations and to establish the proof of concept. This work reports the evaluation of the uptake performance according to the microporous tube length, the liquid flow rate inside the tube, the gas flow rate outside the tube, and the gaseous formaldehyde concentration. A 10.0 cm microporous tube combined with a gas flow rate of 250 NmL/min (normal milliliters per minute) and a liquid flow rate of 17 µL/min were found to be the optimized conditions. In these experimental conditions, the fluorescence signal increased linearly with the gaseous formaldehyde concentration in the range 0–118 µg/m3, with the detection limit being estimated as 0.13 µg/m3 when considering a signal-to-noise ratio of 3.

Transmembrane transport of polycyclic aromatic hydrocarbons by bacteria and functional regulation of membrane proteins

In recent years, increasing research has been conducted on transmembrane transport processes and the mechanisms behind the microbial breakdown of polycyclic aromatic hydrocarbons (PAHs), including the role of membrane proteins in transmembrane transport and the mode of transmission. This article explains the adsorption, uptake and transmembrane transport of PAHs by bacteria, the regulation of membrane protein function during the transmembrane transport. There are three different regulation mechanisms for uptake, depending on the state and size of the oil droplets relative to the size of the microbial cells, which are (i) direct adhesion, (ii) emulsification and pseudosolubilization, and (iii) interfacial uptake. Furthermore, two main transmembrane transport modes are introduced, which are (i) active transport and (ii) passive uptake and active efflux mechanism. Meanwhile, introduce the proteomics and single cell analysis technology used to address these areas of research, such as Isobaric tags for relative and absolute quantitation (iTRAQ) technology and Nano Secondary ion mass spectrometry (Nano-SIMS). Additionally, analyze the changes in morphology and structure and the characteristics of microbial cell membranes in the process of transmembrane transport. Finally, recognize the microscopic mechanism of PAHs biodegradation in terms of cell and membrane proteins are of great theoretical and practical significance for understanding the factors that influence the efficient degradation of PAHs contaminants in soil and for remediating the PAHs contamination in this area with biotechnology.

Rapid and structure-specific cellular uptake of selected steroids.

Steroid hormones and their respective nuclear receptors are essential mediators in numerous physiologic and pathophysiologic processes, ranging from regulation of metabolism, immune function, and reproductive processes to the development of hormone-dependent cancers such as those of the breast and prostate. Because steroids must enter cells before activating nuclear receptors, understanding the mechanisms by which cellular uptake occurs is critical, yet a clear understanding of these mechanisms has been elusive. It is generally assumed that diffusion-driven uptake is similar across various steroids whereas an elevated cellular concentration is thought to reflect active uptake, but these assumptions have not been directly tested. Here we show that intact cells rapidly accumulate free steroids to markedly elevated concentrations. This effect varies widely depending on steroid structure; more lipophilic steroids reach more elevated concentrations. Strong preferences exist for 3β-OH, Δ5-steroids vs. 3-keto, Δ4-structural features and for progestogens vs. androgens. Surprisingly, steroid-structure-specific preferences do not require cell viability, implying a passive mechanism, and occur across cells derived from multiple tissue types. Physiologic relevance is suggested by structure-specific preferences in human prostate tissue compared with serum. On the other hand, the presence of serum proteins in vitro blocks much, but not all, of the passive accumulation, while still permitting a substantial amount of active accumulation for certain steroids. Our findings suggest that both passive and active uptake mechanisms make important contributions to the cellular steroid uptake process. The role of passive, lipophilicity-driven accumulation has previously been largely unappreciated, and its existence provides important context to studies on steroid transport and action both in vitro and in vivo.

Revisiting Alkali Metals As a Tool to Characterize Patterns of Mosquito Dispersal and Oviposition.

Mark-recapture methods constitute a set of classical ecological tools that are used to collect information on species dispersal and population size. These methods have advanced knowledge in disparate scientific fields, from conservation biology to pest control. Gathering information on the dispersal of mosquito species, such as Aedes aegypti, has become critical since the recognition of their role as vectors of pathogens. Here, we evaluate a method to mark mosquitoes that exploits the rare alkali metals rubidium (Rb) and caesium (Cs), which have been used previously to mark adult insects through feeding. We revised this method by adding Rb and Cs directly to water in which the immature stages of Ae. aegypti were allowed to develop. We then assessed the effect of Rb- and Cs-enriched water on fitness, survival and bioaccumulation in both adult females and their eggs. Results indicated that Cs had adverse effects on Ae. aegypti, even at low concentrations, whereas Rb at low concentrations had no measured effects on exposed individuals and accumulated at detectable levels in adult females. The method described here relies on passive uptake of Rb during immature stages, which has the benefit of avoiding handling or manipulation of the dispersive adults, which enables purer measurement of movement. Moreover, we demonstrated that Rb was transferred efficiently from the marked females to their eggs. To our knowledge, Rb is the only marker used for mosquitoes that has been shown to transfer vertically from females to eggs. The application of Rb rather than more traditional markers may therefore increase the quality (no impact on released individuals) and quantity (both adults and eggs are marked) of data collected during MR studies. The method we propose here can be used in combination with other markers, such as stable isotopes, in order to maximize the information collected during MR experiments.

Bioaccumulation Potential of CPs in Aquatic Organisms: Uptake and Depuration in Daphnia magna.

Chlorinated paraffins (CPs) are industrial chemicals, subdivided into three categories: short chain (SCCPs), medium chain (MCCPs), and long chain (LCCPs) chlorinated paraffins. SCCPs are currently restricted in Europe and North America. MC and LCCPs are being used as substitution products, but there is a knowledge gap concerning their bioaccumulation potential in aquatic organisms. In this work, we performed laboratory bioconcentration (passive uptake) and bioaccumulation (including dietary uptake) experiments with Daphnia magna using five different CP technical substances. All tested CP technical substances were bioaccumulative in D. magna, with log BCF and log BAF values ranging between 6.7-7.0 and 6.5-7.0 (L kg lipid-1), respectively. An increase in carbon chain length and an increase in chlorine content (% w/w) of the CP technical substances had significant positive effects on the log BCF and log BAF values. For the different CP technical substances, 50% depuration was achieved after 2 to 10 h when D. magna were transferred to clean media. Our results show that SC, MC, and LCCPs are (very)bioaccumulative in aquatic organisms. We believe these data can aid the ongoing policy discussion concerning the environmental risk posed by CPs.

The Investigation of Silicon Localization and Accumulation in Citrus.

Several studies have demonstrated Si absorption in monocotyledon and dicotyledon species. Regarding Si accumulation, studies in monocotyledons have identified Si deposition around the cell wall, cuticle layer bulliform cells, silica cells and endodermal cells. In previous studies with different citrus species there were evidence of Si accumulation, however no information on Si deposition can be found. Therefore, in this study, Si was applied (0 and 1000 mg L−1) to the roots of two citrus species, ‘Delta’ Valencia (Citrus sinensis) and ‘Nules’ Clementine (Citrus reticulata). Si accumulation were investigated in new, and old leaves and roots. Si deposition was investigated through scanning electron microscopy using energy dispersive analysis X-ray, environmental scanning electron microscopy and light microscopy. Si accumulation was significantly higher in Si treated leaves comparatively to the control in both young and mature leaves. Meanwhile, Si accumulation increased with leaf age. Additionally, Si accumulation was significantly higher in roots than in leaves. With respect to Si deposition, granules were identified in the epidermal cells through SEM and ESEM studies. The light microscopy identified the presence of Si granules in the surface and around the outer cell surface forming the cuticle-silica double layer of the lower epidermis in Si treated plants. Silica deposit were not found on the abaxial leaf surface. The findings suggest a passive uptake in citrus species.

Ion controlled passive nanoparticle uptake in lipid vesicles in theory and experiment

Despite the increasing number of applications of nano-sized particles (NP), there is a lack of systematic basic experimental studies on the physical basics of the interactions between NP and cell membranes. Here, we follow a bottom-up approach and investigate the intake of silica NP by giant unilamellar vesicles. We observe a massive nanoparticle uptake by fluid phase vesicles, but only above a specific ionic strength of the surrounding buffer solution. The uptake rates increase for decreasing NP size and increasing NaCl concentration. A correlation of ionic strength and adhesion force between the lipid membrane and the NP can explain this dependency. We discuss these effects employing a model which considers NP diffusion and an effective membrane permeability due to uptake-induced pores. Our findings contribute to a deeper understanding of the physics behind NP-membrane interactions as well as endocytotic particle uptake in living cells.

PEG-Citrate dendrimer second generation: is this a good carrier for imaging agents In Vitro and In Vivo?

While cancer is the leading cause of human's deaths worldwide, finding an imaging agent which can detect cancer tumours is needed for cancer diagnosis. In the present study, PEG-citrate dendrimer-G2 was used as a nano-carrier of FITC dye and Iohexol to help passive targeting and uptake of both imaging agents in cancer cells/tumour in vitro and in vivo. Dendrimer was synthesisedand the product characterised using LC-MS, FT-IR, DLS, ELS, AFM, and 1HNMR. After FITC loading into dendrimer, MTT was performed to determine the cytotoxicity of formulation on HEK-293 and MCF-7 cells. In vitro imaging using dendrimer-FITC was done via fluorescent microscope thereafter. Moreover, CT imaging using Iohexol was employed to show the targeting nature and ability of the complex to use as imaging agent in vivo. Data yielded in this study corroborate the notion that the promised dendrimer was synthesised properly and had no toxicity along with FITC on normal cell. Furthermore, CT and fluorescent images showed the targeting nature and imaging ability of Iohexol/FITC loaded dendrimer in vitro and in vivo. Overall, results showed promising characteristics of the novel complexes using dendrimer-G2 both in vitro and in vivo.

Biophysical characterization of mycobacterial model membranes and their interaction with rifabutin: Towards lipid-guided drug screening in tuberculosis

Lipid structure critically dictates the molecular interactions of drugs with membranes influencing passive diffusion, drug partitioning and accumulation, thereby underpinning a lipid-composition specific interplay. Spurring selective passive drug diffusion and uptake through membranes is an obvious solution to combat growing antibiotic resistance with minimized toxicities. However, the spectrum of complex mycobacterial lipids and lack thereof of suitable membrane platforms limits the understanding of mechanisms underlying drug-membrane interactions in tuberculosis. Herein, we developed membrane scaffolds specific to mycobacterial outer membrane and demonstrate them as improvised research platforms for investigating anti-tubercular drug interactions. Combined spectroscopy and microscopy results reveal an enhanced partitioning of model drug Rifabutin in trehalose dimycolate-containing mycobacterial membrane systems. These effects are apportioned to specific changes in membrane structure, order and fluidity leading to enhanced drug interaction. These findings on the membrane biophysical consequences of drug interactions will offer valuable insights for guiding the design of more effective antibiotic drugs coupled with tuned toxicity profiles.

The interaction between SBA-15 derivative loaded with Ph3Sn(CH2)6OH and human melanoma A375 cell line: uptake and stem phenotype loss.

Extraordinary progress in medicinal inorganic chemistry in the past few years led to the rational design of novel platinum compounds, as well as nonplatinum metal-based antitumor agents, including organotin compounds, whose activity is not based on unrepairable interaction with DNA. To overcome poor solubility and toxicity problems that limited the application of these compounds numerous delivering systems were used (Lila et al. in Biol Pharm Bull 37:206-211, 2014; Yue and Cao in Curr Cancer Drug Targets 16:480-488, 2016; Duan et al. in WIREs Nanomed Nanobiotechnol 8:776-791, 2016). Regarding high drug loading capacity, mesoporous silica nanoparticles like SBA-15 became more important for targeted drug delivery. In this study, cellular uptake and biological activities responsible for organotin(IV) compound Ph3Sn(CH2)6OH (Sn6) grafted into (3-chloropropyl)triethoxysilane functionalized SBA-15 (SBA-15p → SBA-15p|Sn6) were evaluated in human melanoma A375 cell line. Moreover, the influence of SBA-15p grafted with organotin(IV) compound on the stemness of A375 cell was tested. Given the fact that SBA-15p|Sn6 nanoparticles are nonspherical and relatively large, their internalization efficiently started even after 15min with stable adhesion to the cell membrane. After only 2h of incubation of A375 cells with SBA-15p|Sn6 passive fluid-phase uptake and macropinocytosis were observed. Inside of the cell, treatment with SBA-15p loaded with Sn6 promoted caspase-dependent apoptosis in parallel with senescence development. The subpopulation of cells expressing Schwann-like phenotype arose upon the treatment, while the signaling pathway responsible for maintenance of pluripotency and invasiveness, Wnt, Notch1, and Oct3/4 were modulated towards less aggressive signature. In summary, SBA-15p enhances the efficacy of free Sn6 compound through efficient uptake and well profiled intracellular response followed with decreased stem characteristics of highly invasive A375 melanoma cells.

Mitochondrial transplantation regulates antitumour activity, chemoresistance and mitochondrial dynamics in breast cancer

BackgroundThe transfer of whole mitochondria that occurs during cell contact has been found to support cancer progression. However, the regulatory role of mitochondria alone is difficult to elucidate due to the complex microenvironment. Currently, mitochondrial transplantation is an available approach for restoring mitochondrial function in mitochondrial diseases but remains unclear in breast cancer. Herein, effects of mitochondrial transplantation via different approaches in breast cancer were investigated.MethodsWhole mitochondria (approximately 10.5 μg/ml) were transported into MCF-7 breast cancer cells via passive uptake or Pep-1-mediated delivery. Fresh mitochondria isolated from homeoplasmic 143B osteosarcoma cybrids containing mitochondrial DNA (mtDNA) derived from health individuals (Mito) or mtDNA with the A8344G mutation (Mito8344) were conjugated with cell-penetrating peptide Pep-1 (P-Mito) or not conjugated prior to cell co-culture. Before isolation, mitochondria were stained with MitoTracker dye as the tracking label. After 3 days of treatment, cell viability, proliferation, oxidative stress, drug sensitivity to Doxorubicin/Paclitaxel and mitochondrial function were assessed.ResultsCompared with P-Mito, a small portion of Mito adhered to the cell membrane, and this was accompanied by a slightly lower fluorescent signal by foreign mitochondria in MCF-7 cells. Both transplantations induced cell apoptosis by increasing the nuclear translocation of apoptosis-inducing factor; inhibited cell growth and decreased oxidative stress in MCF-7 cells; and increased the cellular susceptibility of both the MCF-7 and MDA-MB-231 cell lines to Doxorubicin and Paclitaxel. Mitochondrial transplantation also consistently decreased Drp-1, which resulted in an enhancement of the tubular mitochondrial network, but a distinct machinery through the increase of parkin and mitochondrial fusion proteins was observed in the Mito and P-Mito groups, respectively. Furthermore, although there were no differences in energy metabolism after transplantation of normal mitochondria, metabolism was switched to the energetic and glycolytic phenotypes when the mitochondria were replaced with dysfunctional mitochondria, namely, Mito8344 and P-Mito8344, due to dramatically induced glycolysis and reduced mitochondrial respiration, respectively. Consequently, transplant-induced growth inhibition was abolished, and cell growth in the Mito8344 group was even higher than that in the control group.ConclusionThis study reveals the antitumour potential of mitochondrial transplantation in breast cancer via distinct regulation of mitochondrial function.

The Incorporation of Host Proteins into the External HIV-1 Envelope.

The incorporation of biologically active host proteins into HIV-1 is a well-established phenomenon, particularly due to the budding mechanism of viral egress in which viruses acquire their external lipid membrane directly from the host cell. While this mechanism might seemingly imply that host protein incorporation is a passive uptake of all cellular antigens associated with the plasma membrane at the site of budding, this is not the case. Herein, we review the evidence indicating that host protein incorporation can be a selective and conserved process. We discuss how HIV-1 virions displaying host proteins on their surface can exhibit a myriad of altered phenotypes, with notable impacts on infectivity, homing, neutralization, and pathogenesis. This review describes the canonical and emerging methods to detect host protein incorporation, highlights the well-established host proteins that have been identified on HIV-1 virions, and reflects on the role of these incorporated proteins in viral pathogenesis and therapeutic targeting. Despite many advances in HIV treatment and prevention, there remains a global effort to develop increasingly effective anti-HIV therapies. Given the broad range of biologically active host proteins acquired on the surface of HIV-1, additional studies on the mechanisms and impacts of these incorporated host proteins may inform the development of novel treatments and vaccine designs.

Increasing Uptake of Silica Nanoparticles with Electroporation: From Cellular Characterization to Potential Applications.

In the fields of biology and medicine, nanoproducts such as nanoparticles (NPs) are specifically interesting as theranostic tools, since they offer the double capacity to locally deliver active drugs and to image exactly where the product is delivered. Among the many described possibilities, silica nanoparticles (SiNPs) represent a good choice because of their ease of synthesis, the possibility of their vast functionalization, and their good biocompatibility. However, SiNPs’ passive cell internalization by endocytosis only distributes NPs into the cell cytoplasm and is unable to target the nucleus if SiNPs are larger than a few nanometers. In this study, we demonstrate that the cell penetration of SiNPs of 28–30 nm in diameter can be strongly enhanced using a physical method, called electroporation or electropermeabilization (EP). The uptake of fluorescently labelled silica nanoparticles was improved in two different cancer cell lines, namely, HCT-116 (human colon cancer) cells and RL (B-lymphoma) cells. First, we studied cells’ capability for the regular passive uptake of SiNPs in vitro. Then, we set EP parameters in order to induce a more efficient and rapid cell loading, also comprising the nuclear compartment, while preserving the cell viability. In the final approach, we performed in vivo experiments, and evidenced that the labeling was long-lasting, as confirmed by fluorescence imaging of labeled tumors, which enabled a 30-day follow-up. This kind of SiNPs delivery, achieved by EP, could be employed to load extensive amounts of active ingredients into the cell nucleus, and concomitantly allow the monitoring of the long-term fate of nanoparticles.

Effects of available soil silicon on the formation of phytoliths in Phragmites australis (Cav.) Trin. ex Streud, Poaceae

ABSTRACTThe means by which silicon (Si) influences plant growth has important implications for ecology, nature conservation and biogeochemical cycling of Si. To clarify the effect of available soil silicon content on phytolith formation in plants, we studied phytolith in leaves of Phragmites australis (= Phragmites communis), in correlation with available soil silicon, and available silicon in P. australis from 12 sampling sites in Northeast China. The results showed that available soil silicon content and phytolith concentration in P. australis varied across the sampling sites. The differences of available silicon content in P. australis were great among different growing stages. In July and August, silicon absorbed by plant was mainly used for forming phytolith, resulting in a high phytolith concentration, while phytolith concentration was low in September and October. Phytolith concentration was strongly influenced by the ratio of available silicon content in the soil to that in the plant (S/P). The phytolith concentration was high when S/P was less than about 4, and it was low when S/P was more than about 4. The result of redundancy analysis showed that most phytolith morphotypes in P. australis were negatively correlated with S/P. We conclude that silicon uptake of P. australis gradually changes from active uptake to passive uptake when the available soil silicon content is about four times that in P. australis, and in this concentration range the higher available soil silicon content results in phytolith formation. However, if available soil silicon content is too high, it will inhibit phytolith formation.

Enhanced oral bioavailability and brain uptake of Darunavir using lipid nanoemulsion formulation.

The present work aimed to formulate Darunavir loaded lipid nanoemulsion to increase its oral bioavailability and enhance brain uptake. Various batches of lipid nanoemulsion of Darunavir were prepared by high pressure homogenization using soya bean oil, egg lecithin and Tween 80. The optimized batch DNE-3 had globule size of 109.5 nm, zeta potential of -41.1 mV, entrapment efficiency 93% and creaming volume 98%. The batch remained stable at 4 °C for 1 month with an insignificant change in globule size and zeta potential (P > 0.05). In-vivo pharmacokinetics male wistar rats indicated 223% bioavailability of Darunavir relative to drug suspension. Cmax of DNE-3 was twofold higher than suspension form. The organ biodistribution study indicated 2.65 fold higher brain uptake for DNE-3 than that for suspension. The higher bioavailability of Darunavir from nanoemulsion could lessen the dose related side effects. Moreover, high organ distribution results in passive uptake of Darunavir to HIV reservoir organs.

Water absorption into stems affects the measurement of vulnerability curves as a function of plant water status

Xylem hydraulic properties are of great significance for plant growth and performance under drought. The ability of plants to avoid drought-induced cavitation and loss of hydraulic conductivity (K) can be characterized with vulnerability curves (VC). A VC describes the sigmoidal relationship between percentage loss of K (PLC) and xylem water potential (ψxyl). The ψ at 50% loss of conductance indicates a commonly used threshold for detrimental embolism (P50). The slope (b) represents cavitation resistance. The standard hydraulic method to determine VC's requires the measurement of water flow rate (WFR) per pressure gradient through stem segments, either by measuring outflow from the stem gravimetrically or inflow using a flow meter. In a comparative study using both measurements of inflow and outflow in asparagus stems, we found considerable disparities in the resulting shapes of VCs (P50 and b). We hypothesized that water uptake of stem tissue occurs during the pressure-driven water transit, particularly at low water potential and that differences in the initial K might result from measurements of inflow or outflow. To determine whether water uptake of stem tissue occurs during K measurements of asparagus plants, we tested for effects of ψxyl on the initial inflow and outflow K at different pressure gradients and investigated if passive water uptake can be estimated by extrapolation from the linear regression between WFR and pressure gradient based on K at two pressures. Initial K differed significantly between inlet and outlet measurements at low ψxyl, whereas maximum K did not, providing evidence of water uptake during transit through droughted stems. The resulting parameters P50 and b, and thus the shape of VCs, differed as well. The extrapolation resulted in the first estimate of passive water uptake, leading to a convergence of the VC at inlet and at outlet. We conclude that differences between in- and outflow may play a major role in K measurements.

PEGylation Regulates Self-Assembled Small-Molecule Dye-Based Probes from Single Molecule to Nanoparticle Size for Multifunctional NIR-II Bioimaging.

To date, small-molecule dye-based probes have been at the forefront of research in biomedical imaging, especially in the second near-infrared (NIR-II) window (1.0-1.7 µm). However, how to precisely regulate the synthesized size of NIR-II organic dye-based probes remains challenging. Moreover, systematic studies on whether the size of NIR-II probes affects optical/pharmacokinetic properties are still rare. Here, an ingenious PEGylation strategy is developed to regulate the self-assembly size of organic dye-based (CH1055 scaffold) NIR-II probes (SCH1-SCH4) from nanoparticles to the single molecule, and the relationship between their size and chemical/physical properties is thoroughly investigated. Based on their own merits, nanoprobe SCH1 (≈170 nm), with outstanding fluorescent brightness (quantum yield ≈0.14%), performs accurate tracing of the lymphatic system as well as identification of vessel networks in mice brains with excellent signal-to-background ratio images. Meanwhile, rapidly excreted SCH4, showing fast and high passive liver tumor uptake and promising tumor/normal tissue ratios (>7), is capable of facilitating precise image-guided tumor surgery, and also demonstrates the first example of the assessment of liver fibrosis in the NIR-II window.

Cerium oxide nanoparticles at the nano-bio interface: size-dependent cellular uptake

The authors investigated the role of different size and morphology of cerium oxide nanoparticles (CNPs) in cellular uptake and internalization at the nano-bio interface. Atomic force microscopy (AFM) has been utilized to record changes in the membrane elasticity as a function of ceria particle morphology and concentration. Young’s Modulus was estimated in presence and absence of CNPs of different sizes by gauging the membrane elasticity of CCL30 (squamous cell carcinoma) cells. Significant change in Young’s Modulus was observed for CNP treatments at higher concentrations, while minimum membrane disruption was observed at lower concentrations. Studies using blocking agents specific to energy-dependent cellular internalization pathways indicated passive cellular uptake for smaller CNPs (3–5 nm). Other observations showed that larger CNPs were unable to permeate the cell membrane, which indicates an active uptake mechanism by the cell membrane. The ability of smaller CNPs (3–5 nm) to permeate the cell membrane without energy consumption by uptake pathways suggests potential for use as nanovectors for the delivery of bioactive molecules. Specifically, the passive uptake mechanism allows for the delivery of surface-bound molecules directly to the cytoplasm, avoiding the extreme chemical conditions of endosomal pathways.

Sustainable production of biomass and biodiesel by acclimation of non-acidophilic microalgae to acidic conditions

The overwhelming response towards algal biodiesel production has been well-recognized recently as a sustainable alternative to conventional fuels. Most microalgae cannot grow well at acidic pH. The present study, therefore, investigated whether non-acidophilic microalgae Desmodesmus sp. MAS1 and Heterochlorella sp. MAS3 can be acclimated to extreme-acidic pH for sustainable production of biomass and biodiesel. Growth analysis indicated that both the microalgal strains possessed a passive uptake of CO2 at pH 3.0 with biomass production of 0.25 g dry wt. L−1 in Desmodemus sp. and 0.45 g dry wt. L−1 in Heterochlorella sp.. Flow-cytometry analysis for reactive oxygen species, membrane permeability and neutral-lipids revealed the capabilities of both strains to adapt to the stress imposed by acidic pH. Lipid production was doubled in both the strains when grown at pH 3.0. In-situ transesterification of biomass resulted in 13–15% FAME yield in the selected microalgae, indicating their great potential in biofuel production.