Poly(Lactide-co -Glycolide) Nanoparticles, Layer by Layer Engineered for the Sustainable Delivery of AntiTNF-α

Strategies and Progress of Raman Technologies for Cellular Uptake Analysis of the Drug Delivery Systems

Nanoparticle (NP)-based drug delivery systems have the potential to significantly enhance the pharmacological and therapeutic properties of drugs. These systems enhance the bioavailability and biocompatibility of pharmaceutical agents via enabling targeted delivery to specific tissues or organs. However, the efficacy and safety of these systems are largely dependent on the cellular uptake and intracellular transport of NPs. Thus, it is crucial to monitor the intracellular behavior of NPs within a single cell. Yet, it is challenging due to the complexity and size of the cell. Recently, the development of the Raman instrumentation offers a versatile tool to allow noninvasive cellular measurements. The primary objective of this review is to highlight the most recent advancements in Raman techniques (spontaneous Raman scattering, bioorthogonal Raman scattering, coherence Raman scattering, and surface-enhanced Raman scattering) when it comes to assessing the internalization of NP-based drug delivery systems and their subsequent movement within cells.

Pentagalloyl Glucose-Laden Poly(lactide-co-glycolide) Nanoparticles for the Biomechanical Extracellular Matrix Stabilization of an In Vitro Abdominal Aortic Aneurysm Model

The suppression of abdominal aortic aneurysm (AAA) growth by nonsurgical therapy is currently not an option, and AAA is considered an irreversible destructive disease. The formation and development of AAA is associated with the progressive deterioration of the aortic wall. Infiltrated macrophages and resident vascular smooth muscle cells oversecrete matrix metalloproteinases (MMPs), which cause the loss of crucial aortic extracellular matrix (ECM) components, thus weakening the aortic wall. Stabilization of the aortic ECM could enable the development of novel therapeutic options for preventing and reducing AAA progression. In the present work, we studied the biochemical and biomechanical interactions of pentagalloyl glucose (PGG) on mouse C2C12 myoblast cells. PGG is a naturally occurring ECM-stabilizing polyphenolic compound that has been studied in various applications, including vascular health, with promising results. With its known limitations of systemic administration, we also studied the administration of PGG when encapsulated within poly(lactide-co-glycolide) (PLGA) nanoparticles (NPs). Treatment with collagenase and elastase enzymes was used to mimic a pathway of degenerative effects seen in the pathogenesis of human AAA. PGG and PLGA(PGG) NPs were added to enzyme-treated cells in either a suppressive or preventative scenario. Biomolecular interactions were analyzed through cell viability, cell adhesion, reactive oxygen species (ROS) production, and MMP-2 and MMP-9 secretion. Biomechanical properties were studied through atomic force microscopy and quartz crystal microbalance with dissipation. Our results suggest that PGG or PLGA(PGG) NPs caused minor to no cytotoxic effects on the C2C12 cells. Both PGG and PLGA(PGG) NPs showed reduction in ROS and MMP-2 secretion if administered after enzymatic ECM degradation. A quantitative comparison of Young's moduli showed a significant recovery in the elastic properties of the cells treated with PGG or PLGA(PGG) NPs after enzymatic ECM degradation. This work provides preliminary support for the use of a pharmacological therapy for AAA treatment.

Stabilization of Poly (β-Amino Ester) Nanoparticles for the Efficient Intracellular Delivery of PiggyBac Transposon

The administration of gene-editing tools has been proposed as a promising therapeutic approach for correcting mutations that cause diseases. Gene-editing tools, composed of relatively large plasmid DNA constructs that often need to be co-delivered with a guiding protein, are unable to spontaneously penetrate mammalian cells. Although viral vectors facilitate DNA delivery, they are restricted by the size of the plasmid to carry. In this work, we describe a strategy for the stable encapsulation of the gene-editing tool piggyBac transposon into Poly (β-amino ester) nanoparticles (NPs). We propose a non-covalent and a covalent strategy for stabilization of the nanoformulation to slow down release kinetics and enhance intracellular delivery. We found that the formulation prepared by covalently crosslinking Poly (β-amino ester) NPs are capable to translocate into the cytoplasm and nuclei of human glioblastoma (U87MG) cells within 1 h of co-culturing, without the need of a targeting moiety. Once internalized, the nanoformulation dissociates, delivering the plasmid presumably as a response to the intracellular acidic pH. Transfection efficiency is confirmed by green fluorescence protein (GFP) expression in U87MG cells. Covalently stabilized Poly (β-amino ester) NPs are able to transfect ~55% of cells causing non-cytotoxic effects. The strategy described in this work may serve for the efficient non-viral delivery of other gene-editing tools.

Antibacterial Layer-by-Layer Coatings for Medical Implants

The widespread occurrence of nosocomial infections and the emergence of new bacterial strands calls for the development of antibacterial coatings with localized antibacterial action that are capable of facing the challenges posed by increasing bacterial resistance to antibiotics. The Layer-by-Layer (LbL) technique, based on the alternating assembly of oppositely charged polyelectrolytes, can be applied for the non-covalent modification of multiple substrates, including medical implants. Polyelectrolyte multilayers fabricated by the LbL technique have been extensively researched for the development of antibacterial coatings as they can be loaded with antibiotics, antibacterial peptides, nanoparticles with bactericide action, in addition to being capable of restricting adhesion of bacteria to surfaces. In this review, the different approaches that apply LbL for antibacterial coatings, emphasizing those that can be applied for implant modification are presented.

Single cell study of adipose tissue mediated lipid droplet formation and biochemical alterations in breast cancer cells

Obesity is a known risk factor for breast cancer and a negative prognostic factor for cancer recurrence and survival. Several studies demonstrated that aggressive breast tumor cells contain higher numbers of intracellular lipid droplets (LDs). Here we applied simultaneous visualization, identification and quantification of the lipid accumulation in lipid droplets (LDs) of aggressive, human triple-negative MDA-MB-231 breast cancer cells treated with adipose tissue-conditioned medium (ACM) derived from overweight and obese patients. In addition to Oil Red O and AdipoRed fluorescent staining, label-free confocal Raman microspectroscopy (CRM) has been applied. CRM enables imaging of cell compartments as well as quantification and monitoring of specific biomolecules and metabolic processes on a single cell level. Interestingly, breast cancer cells incubated with ACM showed a significantly higher number of intracellular LDs. Cultivation of breast tumor cells with ACM of obese patients induced the formation of LDs with a 20-fold higher lipid concentration than cultivation with basal medium. This is in line with the significantly higher levels of NEFAs (non-esterified fatty acids) detected in the ACM obtained from obese patient compared to ACM obtained from overweight patients or basal medium. Further, by principal component analysis, we identified a significant increase in unsaturation, esterification and lipid to protein ratio in LDs in breast cancer cells incubated with ACM. CRM analyses might function as a valuable diagnostic tool to identify metabolic alterations in biological samples which in turn could provide more detailed insights in the pathogenesis of breast cancer in association with obesity.

The Future of Layer-by-Layer Assembly: A Tribute to ACS Nano Associate Editor Helmuth Möhwald

Layer-by-layer (LbL) assembly is a widely used tool for engineering materials and coatings. In this Perspective, dedicated to the memory of ACS Nano associate editor Prof. Dr. Helmuth Möhwald, we discuss the developments and applications that are to come in LbL assembly, focusing on coatings, bulk materials, membranes, nanocomposites, and delivery vehicles.

Raman Imaging of Nanocarriers for Drug Delivery

The efficacy of pharmaceutical agents can be greatly improved through nanocarrier delivery. Encapsulation of pharmaceutical agents into a nanocarrier can enhance their bioavailability and biocompatibility, whilst also facilitating targeted drug delivery to specific locations within the body. However, detailed understanding of the in vivo activity of the nanocarrier-drug conjugate is required prior to regulatory approval as a safe and effective treatment strategy. A comprehensive understanding of how nanocarriers travel to, and interact with, the intended target is required in order to optimize the dosing strategy, reduce potential off-target effects, and unwanted toxic effects. Raman spectroscopy has received much interest as a mechanism for label-free, non-invasive imaging of nanocarrier modes of action in vivo. Advanced Raman imaging techniques, including coherent anti-Stokes Raman scattering (CARS) and stimulated Raman scattering (SRS), are paving the way for rigorous evaluation of nanocarrier activity at the single-cell level. This review focuses on the development of Raman imaging techniques to study organic nanocarrier delivery in cells and tissues.

Exploring the pH Sensitivity of Poly(allylamine) Phosphate Supramolecular Nanocarriers for Intracellular siRNA Delivery

Silencing RNA (siRNA) technologies emerge as a promising therapeutic tool for the treatment of multiple diseases. An ideal nanocarrier (NC) for siRNAs should be stable at physiological pH and release siRNAs in acidic endosomal pH, fulfilling siRNA delivery only inside cells. Here, we show a novel application of polyamine phosphate NCs (PANs) based on their capacity to load negatively charged nucleic acids and their pH stability. PANs are fabricated by complexation of phosphate anions from phosphate buffer solution (PB) with the amine groups of poly(allylamine) hydrochloride as carriers for siRNAs. PANs are stable in a narrow pH interval, from 7 to 9, and disassemble at pH's higher than 9 and lower than 6. siRNAs are encapsulated by complexation with poly(allylamine) hydrochloride before or after PAN formation. PANs with encapsulated siRNAs are stable in cell media. Once internalized in cells following endocytic pathways, PANs disassemble at the low endosomal pH and release the siRNAs into the cytoplasm. Confocal laser scanning microscopy (CLSM) images of Rhodamine Green labeled PANs (RG-PANs) with encapsulated Cy3-labeled siRNA in A549 cells show that siRNAs are released from the PANs. Colocalization experiments with labeled endosomes and either labeled siRNAs prove the translocation of siRNAs into the cytosol. As a proof of concept, it is shown that PANs with encapsulated green fluorescence protein (GFP) siRNAs silence GFP in A549 cells expressing this protein. Silencing efficacy was evaluated by flow cytometry, CLSM, and Western blot assays. These results open the way for the use of poly(allylamine) phosphate nanocarriers for the intracellular delivery of genetic materials.

Biokinetics of Nanomaterials: the Role of Biopersistence

Nanotechnology risk management strategies and environmental regulations continue to rely on hazard and exposure assessment protocols developed for bulk materials, including larger size particles, while commercial application of nanomaterials (NMs) increases. In order to support and corroborate risk assessment of NMs for workers, consumers, and the environment it is crucial to establish the impact of biopersistence of NMs at realistic doses. In the future, such data will allow a more refined future categorization of NMs. Despite many experiments on NM characterization and numerous in vitro and in vivo studies, several questions remain unanswered including the influence of biopersistence on the toxicity of NMs. It is unclear which criteria to apply to characterize a NM as biopersistent. Detection and quantification of NMs, especially determination of their state, i.e., dissolution, aggregation, and agglomeration within biological matrices and other environments are still challenging tasks; moreover mechanisms of nanoparticle (NP) translocation and persistence remain critical gaps. This review summarizes the current understanding of NM biokinetics focusing on determinants of biopersistence. Thorough particle characterization in different exposure scenarios and biological matrices requires use of suitable analytical methods and is a prerequisite to understand biopersistence and for the development of appropriate dosimetry. Analytical tools that potentially can facilitate elucidation of key NM characteristics, such as ion beam microscopy (IBM) and time-of-flight secondary ion mass spectrometry (ToF-SIMS), are discussed in relation to their potential to advance the understanding of biopersistent NM kinetics. We conclude that a major requirement for future nanosafety research is the development and application of analytical tools to characterize NPs in different exposure scenarios and biological matrices.

High throughput toxicity screening and intracellular detection of nanomaterials

With the growing numbers of nanomaterials (NMs), there is a great demand for rapid and reliable ways of testing NM safety—preferably using in vitro approaches, to avoid the ethical dilemmas associated with animal research. Data are needed for developing intelligent testing strategies for risk assessment of NMs, based on grouping and read‐across approaches. The adoption of high throughput screening (HTS) and high content analysis (HCA) for NM toxicity testing allows the testing of numerous materials at different concentrations and on different types of cells, reduces the effect of inter‐experimental variation, and makes substantial savings in time and cost. HTS/HCA approaches facilitate the classification of key biological indicators of NM‐cell interactions. Validation of in vitroHTS tests is required, taking account of relevance to in vivo results. HTS/HCA approaches are needed to assess dose‐ and time‐dependent toxicity, allowing prediction of in vivo adverse effects. Several HTS/HCA methods are being validated and applied for NM testing in the FP7 project NANoREG, including Label‐free cellular screening of NM uptake, HCA, High throughput flow cytometry, Impedance‐based monitoring, Multiplex analysis of secreted products, and genotoxicity methods—namely High throughput comet assay, High throughput in vitro micronucleus assay, and γH2AX assay. There are several technical challenges with HTS/HCA for NM testing, as toxicity screening needs to be coupled with characterization of NMs in exposure medium prior to the test; possible interference of NMs with HTS/HCA techniques is another concern. Advantages and challenges of HTS/HCA approaches in NM safety are discussed. WIREs Nanomed Nanobiotechnol 2017, 9:e1413. doi: 10.1002/wnan.1413

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Raman microscopy for cellular investigations--From single cell imaging to drug carrier uptake visualization

Progress in advanced therapeutic concepts requires the development of appropriate carrier systems for intracellular drug delivery. Consequently, analysis of interaction between carriers, drugs and cells as well as their uptake and intracellular fate is a current focus of research interest. In this context, Raman spectroscopy recently became an emerging analytical technique, due to its non-destructive, chemically selective and label-free working principle. In this review, we briefly present the state-of-the-art technologies for cell visualization and drug internalization. Against this background, Raman microscopy is introduced as a versatile analytical technique. An overview of various Raman spectroscopy investigations in this field is given including interactions of cells with drug molecules, carrier systems and other nanomaterials. Further, Raman instrumentations and sample preparation methods are discussed. Finally, as the analytical limit is not reached yet, a future perspective for Raman microscopy in pharmaceutical and biomedical research on the single cell level is given.