Luminescent Quantum Dots, Making Invisibles Visible in Bioimaging

Sustained intra-cellular siRNA release from Poly(hypenCapswithspaceRetainColl1rginine) multilayered nanoparticles for prolonged gene silencing

BACKGROUND

Sustained siRNA release from nanocarriers is difficult to achieve inside the cell after entry: typically, all nanocarriers exhibit burst release of the cargo into the cytoplasm.

RESEARCH DESIGN AND METHODS

Layer by layer (LbL) nanoparticles (NPs) can be constructed so that they escape endosomes intact, and subsequently exhibit sustained release of the cargo. Our work quantifies intra-cellular siRNA release from multilayered NPs, evaluates mechanism behind the sustained release, and optimizes the duration of release.

RESULTS

Intra-cellular studies showed that nanoparticles developed with 4 layers of polyL-arginine, alternated with 3 layers of siRNA layers was able to elicit effective and prolonged SPARC knockdown activity over 21 days with a single dose treatment. For the first time, we have quantified the amounts of released siRNA in the cytoplasm and the amount of siRNA remaining inside the nanoparticles at each timepoint. Furthermore, we have correlated the amount of released siRNA within cells by LbL NPs to the cellular knockdown efficiency of multilayered delivery system.

CONCLUSIONS

This methodology may provide an excellent screening tool for assessing the duration of gene silencing by various nanocarrier formulations.

Nanomaterials for Fluorescence and Multimodal Bioimaging

Bioconjugated nanomaterials replace molecular probes in bioanalysis and bioimaging in vitro and in vivo. Nanoparticles of silica, metals, semiconductors, polymers, and supramolecular systems, conjugated with contrast agents and drugs for image-guided (MRI, fluorescence, PET, Raman, SPECT, photodynamic, photothermal, and photoacoustic) therapy infiltrate into preclinical and clinical settings. Small bioactive molecules like peptides, proteins, or DNA conjugated to the surfaces of drugs or probes help us to interface them with cells and tissues. Nevertheless, the toxicity and pharmacokinetics of nanodrugs, nanoprobes, and their components become the clinical barriers, underscoring the significance of developing biocompatible next-generation drugs and contrast agents. This account provides state-of-the-art advancements in the preparation and biological applications of bioconjugated nanomaterials and their molecular, cell, and in vivo applications. It focuses on the preparation, bioimaging, and bioanalytical applications of monomodal and multimodal nanoprobes composed of quantum dots, quantum clusters, iron oxide nanoparticles, and a few rare earth metal ion complexes.

MicroRNA delivery systems in glioma therapy and perspectives: A systematic review

Gliomas are the deadliest of all primary brain tumors, and they constitute a serious global health problem. MicroRNAs (miRNAs) are gene expression regulators associated with glioma pathogenesis. Thus, miRNAs represent potential therapeutic agents for treating gliomas. However, miRNAs have not been established as part of the regular clinical armamentarium. This systemic review evaluates current molecular and pre-clinical studies with the aim of defining the most appealing supramolecular platform for administering therapeutic miRNA to patients with gliomas. An integrated analysis suggested that cationic lipid nanoparticles, functionalized with octa-arginine peptides, represent a potentially specific, practical, non-invasive intervention for treating gliomas. This supramolecular platform allows loading both hydrophilic (miRNA) and hydrophobic (anti-tumor drugs, like temozolomide) molecules. This systemic review is the first to describe miRNA delivery systems targeted to gliomas that integrate several types of molecules as active ingredients. Further experimental validation is warranted to confirm the practical value of miRNA delivery systems.

Development of tumor-specific liposomes containing quantum dots-photosensitizer conjugate used for radiotherapy

This study aims to develop a multifunctional liposomal radiosensitizer to destroy more tumor cells by using lower radiation doses compared to clinically used 6 MV X-ray doses. To achieve this aim, first Chlorine-e6 (Ce6) was covalently bound to functional groups of outer surfaces of quantum dots (QDs) through EDC/NHS reactions. Then, QDs-Ce6 conjugate loaded, nanosized, PEG-coated, and tumor-specific folic acid-modified immunoliposome dispersions were prepared by film method. Enhanced anti-proliferation activity of free and liposomal conjugate against 4T1 (murine breast cancer) cell lines was investigated at different X-ray doses (5, 10, 15, and 20 Gy). As a result, the best radiosensitizer effect was observed at a 5 Gy X-ray dose and it was found that following the X-ray irradiation, immunoliposome dispersions containing QDs-Ce6 conjugate killed 26.8 ± 1.7% more cancer cells than radiation alone.

Improving temozolomide biopharmaceutical properties in glioblastoma multiforme (GBM) treatment using GBM-targeting nanocarriers

Glioblastoma multiforme (GBM) is the most common primary brain cancer. GBM has aggressive development, and the pharmacological treatment remains a challenge due to GBM anatomical characteristics' (the blood-brain barrier and tumor microenvironment) and the increasing resistance to marketed drugs, such as temozolomide (TMZ), the first-line drug for GBM treatment. Due to physical-chemical properties such as short half-life time and the increasing resistance shown by GBM cells, high doses and repeated administrations are necessary, leading to significant adverse events. This review will discuss the main molecular mechanisms of TMZ resistance and the use of functionalized nanocarriers as an efficient and safe strategy for TMZ delivery. GBM-targeting nanocarriers are an important tool for the treatment of GBM, demonstrating to improve the biopharmaceutical properties of TMZ and repurpose its use in anti-GBM therapy. Technical aspects of nanocarriers will be discussed, and biological models highlighting the advantages and effects of functionalization strategies in TMZ anti-GBM activity. Finally, conclusions regarding the main findings will be made in the context of new perspectives for the treatment of GBM using TMZ as a chemotherapy agent, improving the sensibility and biological anti-tumor effect of TMZ through functionalization strategies.

Oligoarginine Peptide Conjugated to BSA Improves Cell Penetration of Gold Nanorods and Nanoprisms for Biomedical Applications

Gold nanoparticles (AuNPs) have been shown to be outstanding tools for drug delivery and biomedical applications, mainly owing to their colloidal stability, surface chemistry, and photothermal properties. The biocompatibility and stability of nanoparticles can be improved by capping the nanoparticles with endogenous proteins, such as albumin. Notably, protein coating of nanoparticles can interfere with and decrease their cell penetration. Therefore, in the present study, we functionalized albumin with the r₈ peptide (All-D, octaarginine) and used it for coating NIR-plasmonic anisotropic gold nanoparticles. Gold nanoprisms (AuNPrs) and gold nanorods (AuNRs) were coated with bovine serum albumin (BSA) previously functionalized using a cell penetrating peptide (CPP) with the r₈ sequence (BSA-r₈). The effect of the coated and r₈-functionalized AuNPs on HeLa cell viability was assessed by the MTS assay, showing a low effect on cell viability after BSA coating. Moreover, the internalization of the nanostructures into HeLa cells was assessed by confocal microscopy and transmission electron microscopy (TEM). As a result, both nanoconstructs showed an improved internalization level after being capped with BSA-r₈, in contrast to the BSA-functionalized control, suggesting the predominant role of CPP functionalization in cell internalization. Thus, our results validate both novel nanoconstructs as potential candidates to be coated by endogenous proteins and functionalized with a CPP to optimize cell internalization. In a further approach, coating AuNPs with CPP-functionalized BSA can broaden the possibilities for biomedical applications by combining their optical properties, biocompatibility, and cell-penetration abilities.

Live-Cell Surface-Enhanced Raman Spectroscopy Imaging of Intracellular pH: From Two Dimensions to Three Dimensions

Visualization of intracellular pH (i-pH) using surface-enhanced Raman spectroscopy (SERS) plays an important role toward understanding of cellular processes including their interactions with nanoparticles. However, conventional two-dimensional SERS imaging often fails to take into consideration changes occurring in the whole-cell volume. We therefore aimed at obtaining a comprehensive i-pH profile of living cells by means of three-dimensional (3D) SERS imaging, thereby visualizing dynamic i-pH distribution changes in a single cell. We devised here a biocompatible and highly stable SERS pH probe, comprising plasmonic gold nanostars functionalized with a pH-sensitive Raman reporter tag-4-mercaptobenzoic acid-and protected by a cationic biocompatible polymer, poly-l-arginine hydrochloride (PA). The positively charged PA coating plays a double role in enhancing cell uptake and providing chemical and colloidal stability in cellular environments. The SERS-active pH probe allowed visualization of local changes in i-pH, such as acidification during nanoparticle (NP) endocytosis. We provide evidence of i-pH changes during NP endocytosis via high-resolution 3D SERS imaging, thereby opening new avenues toward the application of SERS to intracellular studies.

Biodegradable Nanocarriers Resembling Extracellular Vesicles Deliver Genetic Material with the Highest Efficiency to Various Cell Types

Efficient delivery of genetic material to primary cells remains challenging. Here, efficient transfer of genetic material is presented using synthetic biodegradable nanocarriers, resembling extracellular vesicles in their biomechanical properties. This is based on two main technological achievements: generation of soft biodegradable polyelectrolyte capsules in nanosize and efficient application of the nanocapsules for co-transfer of different RNAs to tumor cell lines and primary cells, including hematopoietic progenitor cells and primary T cells. Near to 100% efficiency is reached using only 2.5 × 10^-4 pmol of siRNA, and 1 × 10^-3 nmol of mRNA per cell, which is several magnitude orders below the amounts reported for any of methods published so far. The data show that biodegradable nanocapsules represent a universal and highly efficient biomimetic platform for the transfer of genetic material with the utmost potential to revolutionize gene transfer technology in vitro and in vivo.

Delivery of SiC-based nanoparticles into live cells driven by cell-penetrating peptides SAP and SAP-E

Cell-penetrating peptides enhance nanoparticle delivery into cells most efficiently if surface and peptide functional groups “match” to form non-covalent conjugates.

Charge-driven selective localization of fluorescent nanoparticles in live cells

Covalent grafting of amino groups onto the carboxylic acid functionalities, naturally covering the surface of fluorescent nanoparticles produced from silicon carbide (SiC NPs), allowed tuning of their surface charge from negative to highly positive. Incubating 3T3-L1 fibroblast cells with differently charged SiC NPs demonstrates the crucial role of the charge in cell fluorescent targeting. Negatively charged SiC NPs concentrate inside the cell nuclei. Close to neutrally charged SiC NPs are present in both cytoplasm and nuclei while positively charged SiC NPs are present only in the cytoplasm and are not able to move inside the nuclei. This effect opens the door for the use of SiC NPs for easy and fast visualization of long-lasting biological processes taking place in the cell cytosol or nucleus as well as providing a new long-term cell imaging tool. Moreover, here we have shown that the interaction between charged NPs and nuclear pore complex plays an essential role in their penetration into the nuclei.