Effect of nonendocytic uptake of nanoparticles on human bronchial epithelial cells

Recent Advances in Microscale Electroporation

Electroporation (EP) is a commonly used strategy to increase cell permeability for intracellular cargo delivery or irreversible cell membrane disruption using electric fields. In recent years, EP performance has been improved by shrinking electrodes and device structures to the microscale. Integration with microfluidics has led to the design of devices performing static EP, where cells are fixed in a defined region, or continuous EP, where cells constantly pass through the device. Each device type performs superior to conventional, macroscale EP devices while providing additional advantages in precision manipulation (static EP) and increased throughput (continuous EP). Microscale EP is gentle on cells and has enabled more sensitive assaying of cells with novel applications. In this Review, we present the physical principles of microscale EP devices and examine design trends in recent years. In addition, we discuss the use of reversible and irreversible EP in the development of therapeutics and analysis of intracellular contents, among other noteworthy applications. This Review aims to inform and encourage scientists and engineers to expand the use of efficient and versatile microscale EP technologies.

Nanochannel-Based Poration Drives Benign and Effective Nonviral Gene Delivery to Peripheral Nerve Tissue

While gene and cell therapies have emerged as promising treatment strategies for various neurological conditions, heavy reliance on viral vectors can hamper widespread clinical implementation. Here, the use of tissue nanotransfection as a platform nanotechnology to drive nonviral gene delivery to nerve tissue via nanochannels, in an effective, controlled, and benign manner is explored. TNT facilitates plasmid DNA delivery to the sciatic nerve of mice in a voltage-dependent manner. Compared to standard bulk electroporation (BEP), impairment in toe-spread and pinprick response is not caused by TNT, and has limited to no impact on electrophysiological parameters. BEP, however, induces significant nerve damage and increases macrophage immunoreactivity. TNT is subsequently used to deliver vasculogenic cell therapies to crushed nerves via delivery of reprogramming factor genes Etv2, Foxc2, and Fli1 (EFF). The results indicate the TNT-based delivery of EFF in a sciatic nerve crush model leads to increased vascularity, reduced macrophage infiltration, and improved recovery in electrophysiological parameters compared to crushed nerves that are TNT-treated with sham/empty plasmids. Altogether, the results indicate that TNT can be a powerful platform nanotechnology for localized nonviral gene delivery to nerve tissue, in vivo, and the deployment of reprogramming-based cell therapies for nerve repair/regeneration.

Guided migration analyses at the single-clone level uncover cellular targets of interest in tumor-associated myeloid-derived suppressor cell populations

Myeloid-derived suppressor cells (MDSCs) are immune cells that exert immunosuppression within the tumor, protecting cancer cells from the host’s immune system and/or exogenous immunotherapies. While current research has been mostly focused in countering MDSC-driven immunosuppression, little is known about the mechanisms by which MDSCs disseminate/infiltrate cancerous tissue. This study looks into the use of microtextured surfaces, coupled with in vitro and in vivo cellular and molecular analysis tools, to videoscopically evaluate the dissemination patterns of MDSCs under structurally guided migration, at the single-cell level. MDSCs exhibited topographically driven migration, showing significant intra- and inter-population differences in motility, with velocities reaching ~40 μm h⁻¹. Downstream analyses coupled with single-cell migration uncovered the presence of specific MDSC subpopulations with different degrees of tumor-infiltrating and anti-inflammatory capabilities. Granulocytic MDSCs showed a ~≥3-fold increase in maximum dissemination velocities and traveled distances, and a ~10-fold difference in the expression of pro- and anti-inflammatory markers. Prolonged culture also revealed that purified subpopulations of MDSCs exhibit remarkable plasticity, with homogeneous/sorted subpopulations giving rise to heterogenous cultures that represented the entire hierarchy of MDSC phenotypes within 7 days. These studies point towards the granulocytic subtype as a potential cellular target of interest given their superior dissemination ability and enhanced anti-inflammatory activity.

Cytosolic delivery of quantum dots mediated by freezing and hydrophobic polyampholytes in RAW 264.7 cells

Quantum dots (QDs) can be delivered efficiently inside macrophages using a freeze-concentration approach. In this study, we introduced a new, facile, high concentration-based freezing technology of low toxicity. We also developed QD-conjugated new hydrophobic polyampholytes using poly-l-lysine (PLL), a naturally derived polymer, which showed sustained biocompatibility, stability over one week, and enhanced intracellular delivery. When freeze-concentration was applied, the QD-encapsulated hydrophobic polyampholytes showed a higher tendency to adsorb onto the cell membrane than the non-frozen molecules. Interestingly, we observed that the efficacy of adsorption of QDs on RAW 264.7 macrophages was higher than that on fibroblasts. Furthermore, the intracellular delivery of QDs using hydrophobic polyampholytes was higher than those of PLL and QDs. In vitro studies revealed the efficient endosomal escape of QDs in the presence of hydrophobic polyampholytes and freeze-concentration. Collectively, these observations indicated that the promising combination of freeze-concentration and hydrophobic polyampholytes may act as an effective and versatile strategy for the intracellular delivery of QDs, which can be used for biological diagnosis and therapeutic applications.

Comparative analysis of the cellular entry of polystyrene and gold nanoparticles using the freeze concentration method

Despite advances in nanoparticle delivery, established physical approaches, such as electroporation and sonication, result in cell damage, limiting their practical applications. In this study, we proposed a unique freeze concentration-based technique and evaluated the efficacy of the method using two types of nanoparticles: citrate-capped gold nanoparticles and carboxylated polystyrene nanoparticles. We further compared the internalisation behaviour of particles of various sizes with and without freezing. Confocal microscopic images showed that the uptake efficacy of 50 nm nanomaterials was greater than that of 100 nm particles. Polystyrene nanoparticles of 50 nm size had more favourable adsorption and internalisation behaviours compared to those of gold nanoparticles after freeze concentration. We also examined the possible endocytic pathways involved in the uptake of gold and polystyrene nanoparticles, and found that the route differed between non-frozen and frozen conditions. Overall, we determined the influence of the freeze concentration strategy on both nanomaterial internalisation and the endocytic uptake pathway. Our findings provide a mechanistic understanding of the internalisation of nanoparticles using a freezing approach and thereby contribute to further developments in nanotherapeutic applications.

Review of in vitro toxicological research of quantum dot and potentially involved mechanisms

Quantum dots (QDs) are one of emerging engineering nanomaterials (NMs) with advantageous properties which can act as candidates for clinical imaging and diagnosis. Nevertheless, toxicological studies have proved that QDs for better or worse pose threats to diverse systems which are attributed to the release of metal ion and specific characteristics of nanoparticles (NPs), hampering the wide use of QDs to biomedical area. It has been postulated that mechanisms of toxicity evoked by QDs have implications in oxidative stress, reactive oxygen species (ROS), inflammation and release of metal ion. Meanwhile, DNA damage and disturbance of subcellular structures would occur during QDs treatment. This review is intended to conclude the cytotoxicity of QDs in multiple systems, as well as the potential mechanisms on the basis of recent literatures. Finally, toxicity-related factors are clarified, among which chirality seems to be a newly proposed influence factor that determines the destiny of cells in response to QDs. However, details of interaction between QDs and cells have not been well elucidated. Given that molecular mechanisms of QDs-induced toxicity are still not clearly elucidated, further research should be required for this meaningful topic.

Application of semiconductor quantum dots in bioimaging and biosensing

In this review we present new concepts and recent progress in the application of semiconductor quantum dots (QD) as labels in two important areas of biology, bioimaging and biosensing.

RETRACTED: Designing of carbon based fluorescent nanosea-urchin via green-synthesis approach for live cell detection of zinc oxide nanoparticle

This article has been retracted: please see Elsevier Policy on Article Withdrawal (https://www.elsevier.com/about/our-business/policies/article-withdrawal). This article has been retracted at the request of Editor following concerns raised by a reader. There are significant concerns regarding the originality of the electron micrographs displayed in Fig. 1 (panels B-G, especially C). The concern is that these multi-particle images are comprised of copies of the same particles. These problems with the data presented cast doubt on all the data, and accordingly also the conclusions based on that data, in this publication. As such this article represents a severe abuse of the scientific publishing system. The scientific community takes a very strong view on this matter and apologies are offered to readers of the journal that this was not detected during the submission process

Unconventional micro-/nanofabrication technologies for hybrid-scale lab-on-a-chip

Micro-/nanofabrication-based lab-on-a-chip (LOC) technologies have recently been substantially advanced and have become widely used in various inter-/multidisciplinary research fields, including biological, (bio-)chemical, and biomedical fields. However, such hybrid-scale LOC devices are typically fabricated using microfabrication and nanofabrication processes in series, resulting in increased cost and time and low throughput issues. In this review, after briefly introducing the conventional micro-/nanofabrication technologies, we focus on unconventional micro-/nanofabrication technologies that allow us to produce either in situ micro-/nanoscale structures or master molds for additional replication processes to easily and conveniently create novel LOC devices with micro- or nanofluidic channel networks. In particular, microfabrication methods based on crack-assisted photolithography and carbon-microelectromechanical systems (C-MEMS) are described in detail because of their superior features from the viewpoint of the throughput, batch fabrication process, and mixed-scale channels/structures. In parallel with previously reported articles on conventional micro-/nanofabrication technologies, our review of unconventional micro-/nanofabrication technologies will provide a useful and practical fabrication guideline for future hybrid-scale LOC devices.

Intracellular imaging of quantum dots, gold, and iron oxide nanoparticles with associated endocytic pathways

Metallic nanoparticles (NP) have been used for biomedical applications especially for imaging. Compared to nonmetallic NP, metallic NP provide high contrast images because of their optical light scattering, magnetic resonance, X-ray absorption, or other physicochemical properties. In this review, a series of in vitro imaging techniques for metallic NP will be introduced, meanwhile their strengths and weaknesses will be discussed. By utilizing these imaging methods, the cellular uptake of metallic NP can be easily visualized to better understand the endocytic mechanisms of NP intracellular delivery. Several types of metallic NP that are used for imaging or as contrast agents such as quantum dots, gold, iron oxide, and other metallic NP will be presented. Cellular uptake of metallic NP and associated endocytic mechanisms highly depends upon the NP size, charge, surface coating, shape, or other factors such as cell type, cell differentiation status, cell surface status, external forces, protein binding, temperature, and the biological milieu. Classical endocytic routes such as lipid raft-mediated pathways, clathrin or caveolae-mediated pathways, macropinocytosis, and phagocytosis have been investigated, yet there is still a demand to determine other endocytic pathways. Knowing the different methodologies used to determine the endocytic pathways will increase the understanding of NP toxicity, cancer cell targeting, and imaging, so that surface coatings can be created for efficient cell uptake of metallic NP with minimal cytotoxicity WIREs Nanomed Nanobiotechnol 2017, 9:e1419. doi: 10.1002/wnan.1419 For further resources related to this article, please visit the WIREs website.

Metal-based quantum dots: synthesis, surface modification, transport and fate in aquatic environments and toxicity to microorganisms

The intense interest in metal-based QDs is diluted by the fact that they cause risks to aquatic environments.

Nanochannel Electroporation as a Platform for Living Cell Interrogation in Acute Myeloid Leukemia

A living cell interrogation platform based on nanochannel electroporation is demonstrated with analysis of RNAs in single cells. This minimally invasive process is based on individual cells and allows both multi-target analysis and stimulus-response analysis by sequential deliveries. The unique platform possesses a great potential to the comprehensive and lysis-free nucleic acid analysis on rare or hard-to-transfect cells.