Dye-Loaded Nanoemulsions: Biomimetic Fluorescent Nanocarriers for Bioimaging and Nanomedicine

Photophysics of fluorescent nanoparticles based on organic dyes - challenges and design principles

Fluorescent nanoparticles have become attractive for bioanalysis and imaging, due to their high brightness and photostability. Many different optical materials have been applied in fluorescent nanoparticles with a broad range of properties and characteristics. One appealing approach is the incorporation of molecular organic fluorophores in nanoparticles with the intention of transferring their known attractive solution-state properties directly to the nanoparticles. However, as molecular dyes are packed closely together in the nanoparticles their interactions most often result in fluorescence quenching and change in spectral properties making this approach challenging. In this perspective we will first discuss the origins of quenching and spectral shifts observed in dye based nanoparticles. On this background, we will then describe various designs of dye based NPs and how they address the challenges of dye-dye interactions and quenching. Our aim is to provide a general framework for understanding the supramolecular mechanisms that determine the photophysics of dye based nanoparticles. This framework of molecular photophysics and its relation to the internal structure of dye based nanoparticles can hopefully serve to assist rational design and optimization of new and improved dye based nanoparticles.

Magneto-optical nanosystems for tumor multimodal imaging and therapy in-vivo

Multimodal imaging, which combines the strengths of two or more imaging modalities to provide complementary anatomical and molecular information, has emerged as a robust technology for enhancing diagnostic sensitivity and accuracy, as well as improving treatment monitoring. Moreover, the application of multimodal imaging in guiding precision tumor treatment can prevent under- or over-treatment, thereby maximizing the benefits for tumor patients. In recent years, several intriguing magneto-optical nanosystems with both magnetic and optical properties have been developed, leading to significant breakthroughs in the field of multimodal imaging and image-guided tumor therapy. These advancements pave the way for precise tumor medicine. This review summarizes various types of magneto-optical nanosystems developed recently and describes their applications as probes for multimodal imaging and agents for image-guided therapeutic interventions. Finally, future research and development prospects of magneto-optical nanosystems are discussed along with an outlook on their further applications in the biomedical field.

Nanosensor based approaches for quantitative detection of heparin

Heparin, being a widely employed anticoagulant in numerus clinical complications, requires strict quantification and qualitative screening to ensure the safety of patients from potential threat of thrombocytopenia. However, the intricacy of heparin's chemical structures and low abundance hinders the precise monitoring of its level and quality in clinical settings. Conventional laboratory assays have limitations in sensitivity and specificity, necessitating the development of innovative approaches. In this context, nanosensors emerged as a promising solution due to enhanced sensitivity, selectivity, and ability to detect heparin even at low concentrations. This review delves into a range of sensing approaches including colorimetric, fluorometric, surface-enhanced Raman spectroscopy, and electrochemical techniques using different types of nanomaterials, thus providing insights of its principles, capabilities, and limitations. Moreover, integration of smart-phone with nanosensors for point of care diagnostics has also been explored. Additionally, recent advances in nanopore technologies, artificial intelligence (AI) and machine learning (ML) have been discussed offering specificity against contaminants present in heparin to ensure its quality. By consolidating current knowledge and highlighting the potential of nanosensors, this review aims to contribute to the advancement of efficient, reliable, and economical heparin detection methods providing improved patient care.

To see or not to see: In vivo nanocarrier detection methods in the brain and their challenges

Nanoparticles have a great potential to significantly improve the delivery of therapeutics to the brain and may also be equipped with properties to investigate brain function. The brain, being a highly complex organ shielded by selective barriers, requires its own specialized detection system. However, a significant hurdle to achieve these goals is still the identification of individual nanoparticles within the brain with sufficient cellular, subcellular, and temporal resolution. This review aims to provide a comprehensive summary of the current knowledge on detection systems for tracking nanoparticles across the blood-brain barrier and within the brain. We discuss commonly employed in vivo and ex vivo nanoparticle identification and quantification methods, as well as various imaging modalities able to detect nanoparticles in the brain. Advantages and weaknesses of these modalities as well as the biological factors that must be considered when interpreting results obtained through nanotechnologies are summarized. Finally, we critically evaluate the prevailing limitations of existing technologies and explore potential solutions.

Hyperpolarized 129Xe Atoms Sense the Presence of Drug Molecules in Nanohosts Revealed by Magnetic Resonance Imaging

Assessing the effectiveness of nanomedicines involves evaluating the drug content at the target site. Currently, most research focuses on monitoring the signal responses from loaded drugs, neglecting the changes caused by the nanohosts. Here, we propose a strategy to quantitatively evaluate the content of loaded drugs by detecting the signal variations resulting from the alterations in the microenvironment of the nanohosts. Specifically, hyperpolarized (HP) 129Xe atoms are employed as probes to sense the nanohosts' environment and generate a specific magnetic resonance (MR) signal that indicates their accessibility. The introduction of drugs reduces the available space in the nanohosts, leading to a crowded microenvironment that hinders the access of the 129Xe atoms. By employing 129Xe atoms as a signal source to detect the alterations in the microenvironment, we constructed a three-dimensional (3D) map that indicated the concentration of the nanohosts and established a linear relationship to quantitatively measure the drug content within the nanohosts based on the corresponding MR signals. Using the developed strategy, we successfully quantified the uptake of the nanohosts and drugs in living cells through HP 129Xe MR imaging. Overall, the proposed HP 129Xe atom-sensing approach can be used to monitor alterations in the microenvironment of nanohosts induced by loaded drugs and provides a new perspective for the quantitative evaluation of drug presence in various nanomedicines.

A comprehensive review on the biomedical frontiers of nanowire applications

This comprehensive review examines the immense capacity of nanowires, nanostructures characterized by unbounded dimensions, to profoundly transform the field of biomedicine. Nanowires, which are created by combining several materials using techniques such as electrospinning and vapor deposition, possess distinct mechanical, optical, and electrical properties. As a result, they are well-suited for use in nanoscale electronic devices, drug delivery systems, chemical sensors, and other applications. The utilization of techniques such as the vapor-liquid-solid (VLS) approach and template-assisted approaches enables the achievement of precision in synthesis. This precision allows for the customization of characteristics, which in turn enables the capability of intracellular sensing and accurate drug administration. Nanowires exhibit potential in biomedical imaging, neural interfacing, and tissue engineering, despite obstacles related to biocompatibility and scalable manufacturing. They possess multifunctional capabilities that have the potential to greatly influence the intersection of nanotechnology and healthcare. Surmounting present obstacles has the potential to unleash the complete capabilities of nanowires, leading to significant improvements in diagnostics, biosensing, regenerative medicine, and next-generation point-of-care medicines.

Biosynthesized metallic nanoparticles: A new era in cancer therapy

Cancer remains a global health crisis, claiming countless lives throughout the years. Traditional cancer treatments like chemotherapy and radiation often bring about severe side effects, underscoring the pressing need for innovative, more efficient, and less toxic therapies. Nanotechnology has emerged as a promising technology capable of producing environmentally friendly anticancer nanoparticles. Among various nanoparticle types, metal-based nanoparticles stand out due to their exceptional performance and ease of use in methods of imaging. The widespread accessibility of biological precursors for synthesis based on plants of metal nanoparticles has made large-scale, eco-friendly production feasible. This evaluation provides a summary of the green strategy for synthesizing metal-based nanoparticles and explores their applications. Moreover, this review delves into the potential of phyto-based metal nanoparticles in combating cancer, shedding light on their probable mechanisms of action. These insights are invaluable for enhancing both biomedical and environmental applications. The study also touches on the numerous potential applications of nanotechnology in the field of medicine. Consequently, this research offers a concise and well-structured summary of nanotechnology, which should prove beneficial to researchers, engineers, and scientists embarking on future research endeavors.

Focused ion beam-scanning electron microscopy provides novel insights of drug delivery phenomena

Scanning electron microscopy (SEM) has long been a standard tool for morphological analyses, providing sub micrometer resolution of pharmaceutical formulations. However, analysis of internal morphologies of such formulations can often be biased due to the introduction of artifacts that originate from sample preparation. A recent advancement in SEM, is the focused ion beam scanning electron microscopy (FIB-SEM). This technique uses a focused ion beam (FIB) to remove material with nanometer precision, to provide virtually sample-independent access to sub-surface structures. The FIB can be combined with SEM imaging capabilities within the same instrumentation. As a powerful analytical tool, electron microscopy and FIB-milling are performed sequentially to produce high-resolution 3D models of structural peculiarities of diverse drug delivery systems or their behavior in a biological environment, i.e. intracellular or -tissue distribution. This review paper briefly describes the technical background of the method, outlines a wide array of potential uses within the drug delivery field, and focuses on intracellular transport where high-resolution images are an essential tool for mechanistical insights.

Biomaterials for Drug Delivery and Human Applications

Biomaterials embody a groundbreaking paradigm shift in the field of drug delivery and human applications. Their versatility and adaptability have not only enriched therapeutic outcomes but also significantly reduced the burden of adverse effects. This work serves as a comprehensive overview of biomaterials, with a particular emphasis on their pivotal role in drug delivery, classifying them in terms of their biobased, biodegradable, and biocompatible nature, and highlighting their characteristics and advantages. The examination also delves into the extensive array of applications for biomaterials in drug delivery, encompassing diverse medical fields such as cancer therapy, cardiovascular diseases, neurological disorders, and vaccination. This work also explores the actual challenges within this domain, including potential toxicity and the complexity of manufacturing processes. These challenges emphasize the necessity for thorough research and the continuous development of regulatory frameworks. The second aim of this review is to navigate through the compelling terrain of recent advances and prospects in biomaterials, envisioning a healthcare landscape where they empower precise, targeted, and personalized drug delivery. The potential for biomaterials to transform healthcare is staggering, as they promise treatments tailored to individual patient needs, offering hope for improved therapeutic efficacy, fewer side effects, and a brighter future for medical practice.

Supra-Cyanines: Ultrabright Cyanine-Based Fluorescent Supramolecular Materials in Solution and in the Solid State

Fluorescent materials with high brightness play a crucial role in the advancement of various technologies such as bioimaging, photonics, and OLEDs. While significant efforts are dedicated to designing new organic dyes with improved performance, enhancing the brightness of existing dyes holds equal importance. In this study, we present a simple supramolecular strategy to develop ultrabright cyanine-based fluorescent materials by addressing long-standing challenges associated with cyanine dyes, including undesired cis-trans photoisomerization and aggregation-caused quenching. Supra-cyanines are obtained by incorporating cyanine moieties in a cyclic peptide-based supramolecular scaffold, and exhibit high fluorescence quantum yields (up to 50 %) in both solution and in the solid state. These findings offer a versatile approach for constructing highly emissive cyanine-based supramolecular materials.

Precious metal clusters as fundamental agents in bioimaging usability

Fluorescent nanomaterials (NMs) are widely used in imaging techniques in biomedical research. Especially in bioimaging systems, with the rapid development of imaging nanotechnology, precious metal clusters such as Au, Ag, and Cu NMs have emerged with different functional agents for biomedical applications. Compared with traditional fluorescent molecules, precious metal clusters have the advantages of high optical stability, easy regulation of shape and size, and multifunctionalization. In addition, NMs possess strong photoluminescent properties with good photostability, high release rate, and sub-nanometer size. They could be treated as fundamental agents in bioimaging usability. This review summarizes the recent advances in bioimaging utilization, it conveys that metal clusters refer to Au, Ag, and Cu fluorescent clusters and could provide a generalized overview of their full applications. It includes optical property measurement, precious metal clusters in bioimaging systems, and a rare earth element-doped heterogeneous structure illustrated in biomedical imaging with specific examples, that provide new and innovative ideas for fluorescent NMs in the field of bioimaging usability.

Cancer-Associated Fibroblast Mimetic AIE Probe for Precision Imaging-Guided Full-Cycle Management of Ovarian Cancer Surgery

Fluorescence imaging can improve surgical accuracy in ovarian cancer, but a high signal-to-noise ratio is crucial for tiny metastatic cancers. Meanwhile, intraoperative fluorescent surgical navigation modalities alone are still insufficient to completely remove ovarian cancer lesions, and the recurrence rate remains high. Here, we constructed a cancer-associated fibroblasts (CAFs)-mimetic aggregation-induced emission (AIE) probe to enable full-cycle management of surgery that eliminates recurrence. AIE molecules (P3-PPh3) were packed in hollow mesoporous silica nanoparticles (HMSNs) to form HMSN-probe and then coated with a CAFs membrane to prepare CAF-probe. First, due to the negative potential of the CAF-probe, the circulation time in vivo is elevated, which facilitates passive tumor targeting. Second, the CAF-probe avoids its clearance by the immune system and improves the bioavailability. Finally, the fibronectin on the CAF-probe specifically binds to integrin α-5 (ITGA5), which is highly expressed in ovarian cancer cells, enabling fluorescence imaging with a contrast of up to 8.6. CAF-probe-based fluorescence imaging is used to evaluate the size and location of ovarian cancer before surgery (preoperative evaluation), to guide tumor removal during surgery (intraoperative navigation), and to monitor tumor recurrence after surgery (postoperative monitoring), ultimately significantly improving the efficiency of surgery and completely eliminating tumor recurrence. In conclusion, we constructed a CAFs mimetic AIE probe and established a full-cycle surgical management model based on its precise imaging properties, which significantly reduced the recurrence of ovarian cancer.

A critical review of the novelties in the development of intravenous nanoemulsions

Nanoemulsions have gained increasing attention in recent years as a drug delivery system due to their ability to improve the solubility and bioavailability of poorly water-soluble drugs. This systematic review aimed to collect and critically analyze recent novelties in developing, designing, and optimizing intravenous nanoemulsions appearing in articles published between 2017 and 2022. The applied methodology involved searching two electronic databases PubMed and Scopus, using the keyword "nanoemulsion" in combination with "intravenous" or "parenteral". The resulting original articles were classified by the method of preparation into different categories. An overview of the current methods used for the preparation of such formulations, including high- and low-energy emulsification, was provided. The advantages and disadvantages of these methods were discussed, as well as their potential impact on the properties of the developed intravenous nanoemulsions. The problem of inconsistency in intravenous nanoemulsion terminology may lead to misunderstandings and misinterpretations of their properties and applications was also undertaken. Finally, the regulatory aspects of intravenous nanoemulsions, the state of the art in the field of intravenous emulsifiers, and the future perspectives were presented.

Proteinoid Polymers and Nanocapsules for Cancer Diagnostics, Therapy and Theranostics: In Vitro and In Vivo Studies

Proteinoids-simple polymers composed of amino acids-were suggested decades ago by Fox and coworkers to form spontaneously by heat. These special polymers may self-assemble in micrometer structures called proteinoid microspheres, presented as the protocells of life on earth. Interest in proteinoids increased in recent years, in particular for nano-biomedicine. They were produced by stepwise polymerization of 3-4 amino acids. Proteinoids based on the RGD motif were prepared for targeting tumors. Nanocapsules form by heating proteinoids in an aqueous solution and slowly cooling to room temperature. Proteinoid polymers and nanocapsules suit many biomedical applications owing to their non-toxicity, biocompatibility and immune safety. Drugs and/or imaging reagents for cancer diagnostic, therapeutic and theranostic applications were encapsulated by dissolving them in aqueous proteinoid solutions. Here, recent in vitro and in vivo studies are reviewed.

In Vivo Fluorescence Imaging-Guided Development of Near-Infrared AIEgens

In vivo fluorescence imaging has received extensive attention due to its distinguished advantages of excellent biosafety, high sensitivity, dual temporal-spatial resolution, real-time monitoring ability, and non-invasiveness. Aggregation-induced emission luminogens (AIEgens) with near-infrared (NIR) absorption and emission wavelengths are ideal candidate for in vivo fluorescence imaging for their large Stokes shift, high brightness and superior photostability. NIR emissive AIEgens provide deep tissue penetration depth as well as low interference from tissue autofluorescence. Here in this review, we summarize the molecular engineering strategies for constructing NIR AIEgens with high performances, including extending π-conjugation system and strengthen donor (D)-acceptor (A) interactions. Then the encapsulation strategies for increasing water solubility and biocompatibility of these NIR AIEgens are highlighted. Finally, the challenges and prospect of fabricating NIR AIEgens for in vivo fluorescence imaging are also discussed. We hope this review would provide some guidelines for further exploration of new NIR AIEgens.

Controlled Release and Capture of Aldehydes by Dynamic Imine Chemistry in Nanoemulsions: From Delivery to Detoxification

Current biomedical applications of nanocarriers are focused on drug delivery, where encapsulated cargo is released in the target tissues under the control of external stimuli. Here, we propose a very different approach, where the active toxic molecules are removed from biological tissues by the nanocarrier. It is based on the drug-sponge concept, where specific molecules are captured by the lipid nanoemulsion (NE) droplets due to dynamic covalent chemistry inside their oil core. To this end, we designed a highly lipophilic amine (LipoAmine) capable of reacting with a free cargo-aldehyde (fluorescent dye and 4-hydroxynonenal toxin) directly inside lipid NEs, yielding a lipophilic imine conjugate well encapsulated in the oil core. The formation of imine bonds was first validated using a push-pull pyrene aldehyde dye, which changes its emission color during the reaction. The conjugate formation was independently confirmed by mass spectrometry. As a result, LipoAmine-loaded NEs spontaneously loaded cargo-aldehydes, yielding formulations stable against leakage at pH 7.4, which can further release the cargo in a low pH range (4-6) in solutions and living cells. Using fluorescence microscopy, we showed that LipoAmine NEs can extract pyrene aldehyde dye from cells as well as from an epithelial tissue (chicken skin). Moreover, successful extraction from cells was also achieved for a highly toxic aliphatic aldehyde 4-hydroxynonenal, which allowed obtaining the proof of concept for detoxification of living cells. Taken together, these results show that the dynamic imine chemistry inside NEs can be used to develop detoxification platforms.

Updated insight into the characterization of nano-emulsions

INTRODUCTION

In most of the studies, nano-emulsion characterization is limited to their size distribution and zeta potential. In this review, we present an updated insight of the characterization methods of nano-emulsions, including new or unconventional experimental approaches to explore in depth the nano-emulsion properties.

AREA COVERED

We propose an overview of all the main techniques used to characterize nano-emulsions, including the most classical ones, up to in vitro, ex vivo and in vivo evaluation. Innovative approaches are then presented in the second part of the review that presents innovative, experimental techniques less known in the field of nano-emulsion such as the nanoparticle tracking analysis, small-angle X-ray scattering, Raman spectroscopy, and nuclear magnetic resonance. Finally, in the last part we discuss the use of lipophilic fluorescent probes and imaging techniques as an emerging tool to understand the nano-emulsion droplet stability, surface decoration, release mechanisms, and in vivo fate.

EXPERT OPINION

This review is mostly intended for a broad readership and provides key tools regarding the choice of the approach to characterize nano-emulsions. Innovative and uncommon methods will be precious to disclose the information potentially reachable behind a formulation of nano-emulsions, not always known in first intention and with conventional methods.

Tuning Properties of Polyelectrolyte-Surfactant Associates in Two-Phase Microfluidic Flows

This work focuses on identifying and prioritizing factors that allow control of the properties of polyelectrolyte-surfactant complexes in two-phase microfluidic confinement and provide advantages over synthesis of such complexes in macroscopic conditions. We characterize the impact of polymer and surfactant aqueous flow conditions on the formation of microscale droplets and fluid threads in the presence of an immiscible organic solvent. We perform an experimental and selected numerical analysis of fast supramolecular reactions in droplets and threads. The work offers a quantitative control over properties of polyelectrolyte-surfactant complexes produced in two-phase confinement by varying capillary numbers and the ratio of aqueous and organic flowrates. We propose a combined thread-droplet mode to synthesize polyelectrolyte-surfactant complexes. This mode allows the production of complexes in a broader size range of R ≈ 70-200 nm, as compared with synthesis in macroscopic conditions and the respective sizes R ≈ 100-120 nm. Due to a minimized impact of undesirable post-chip reactions and ordered microfluidic confinement conditions, the dispersity of microfluidic aggregates (PDI = 0.2-0.25) is lower than that of their analogs synthesized in bulk (PDI = 0.3-0.4). The proposed approach can be used for tailored synthesis of target drug delivery polyelectrolyte-surfactant systems in lab-on-chip devices for biomedical applications.

Fluorescent Multifunctional Organic Nanoparticles for Drug Delivery and Bioimaging: A Tutorial Review

Fluorescent organic nanoparticles (FONs) are a large family of nanostructures constituted by organic components that emit light in different spectral regions upon excitation, due to the presence of organic fluorophores. FONs are of great interest for numerous biological and medical applications, due to their high tunability in terms of composition, morphology, surface functionalization, and optical properties. Multifunctional FONs combine several functionalities in a single nanostructure (emission of light, carriers for drug-delivery, functionalization with targeting ligands, etc.), opening the possibility of using the same nanoparticle for diagnosis and therapy. The preparation, characterization, and application of these multifunctional FONs require a multidisciplinary approach. In this review, we present FONs following a tutorial approach, with the aim of providing a general overview of the different aspects of the design, preparation, and characterization of FONs. The review encompasses the most common FONs developed to date, the description of the most important features of fluorophores that determine the optical properties of FONs, an overview of the preparation methods and of the optical characterization techniques, and the description of the theoretical approaches that are currently adopted for modeling FONs. The last part of the review is devoted to a non-exhaustive selection of some recent biomedical applications of FONs.

NIR-II-Excitable Dye-Loaded Nanoemulsions for Two-Photon Microscopy Imaging of Capillary Blood Vessels in the Entire Hippocampal CA1 Region of Living Mice

For in vivo two-photon fluorescence microscopy (2PM) imaging, the development of techniques that can improve the observable depth and temporal resolution is an important challenge to address biological and biomedical concerns such as vascular dynamics in the deep brain (typically the hippocampal region) of living animals. Improvements have been achieved through two approaches: an optical approach using a highly tissue-penetrating excitation laser oscillating in the second near-infrared wavelength region (NIR-II, 1100-1350 nm) and a chemical approach employing fluorescent probes with high two-photon brightness (characterized by the product of the two-photon absorption cross section, σ², and the fluorescence quantum yield, Φ). To integrate these two approaches, we developed a fluorescent dye exhibiting a sufficiently high σ²Φ value of 68 Goeppert-Mayer units at 1100 nm. When a nanoemulsion encapsulating >1000 dye molecules per particle and a 1100 nm laser were employed for 2PM imaging, capillary blood vessels in almost the entire hippocampal CA1 region of the mouse brain (approximately 1.1-1.5 mm below the surface) were clearly visualized at a frame rate of 30 frames s^-1 (averaged over eight frames, practically 3.75 frames s^-1). This observable depth and frame rate are much higher than those in previous reports on 2PM imaging. Furthermore, this nanoemulsion allowed for the visualization of blood vessels at a depth of 1.8 mm, corresponding to the hippocampal dentate gyrus. These results highlight the advantage of combining bright probes with NIR-II lasers. Our probe is a promising tool for studying the vascular dynamics of living animals and related diseases.

FRET as the tool for in vivo nanomedicine tracking

Advanced drug delivery system utilizing a nanocarrier is the major application of nanotechnology on pharmacotherapeutics. However, despite the promising benefits and a leading trend in pharmaceutical research, nanomedicine development suffers from a poor clinical translation problem as only a handful of nanomedicine products reach the market yearly. The conventional pharmacokinetic study generally focuses only on monitoring the level of a free drug but ignores the nanocarrier's role in pharmacokinetics. One hurdle is that it is difficult to directly track intact nanocarriers in vivo to explore their pharmacokinetics. Although several imaging techniques such as radiolabeling, nuclear imaging, fluorescence imaging, etc., have been developed over the past few years, currently, one method that can successfully track the intact nanocarriers in vivo directly is by Förster resonance energy transfer (FRET). This review summarizes the application of FRET as the in vivo nanoparticle tracker for studying the in vivo pharmacokinetics of the organic nanocarriers and gives elaborative details on the techniques utilized.

Biodistribution, pharmacokinetics and excretion studies of intravenously injected nanoparticles and extracellular vesicles: Possibilities and challenges

There is a large interest in developing nanoparticles and extracellular vesicles for delivery of therapeutics or imaging agents. Regulatory approval of such products requires knowledge about their biodistribution, metabolism and excretion. We here discuss possibilities and challenges of methods used for such studies, which most often are performed after labelling with radioactive isotopes or fluorescent molecules. It is important to evaluate if the labelled and unlabeled products can be expected to behave similarly in the body. Furthermore, one needs to critically consider whether the labels are still associated with the product at the time of analyses. We discuss advantages and disadvantages of different imaging modalities such as PET, SPECT, MRI, CT, ultrasound and optical imaging for whole-body biodistribution, and describe how to estimate the amount of labelled product in harvested organs and tissue. Microscopy of cells and tissues and various mass spectrometry methods are also discussed in this review.

Rosmarinic Acid-Loaded Polymeric Nanoparticles Prepared by Low-Energy Nano-Emulsion Templating: Formulation, Biophysical Characterization, and In Vitro Studies

Rosmarinic acid (RA), a caffeic acid derivative, has been loaded in polymeric nanoparticles made up of poly(lactic-co-glycolic acid) (PLGA) through a nano-emulsion templating process using the phase-inversion composition (PIC) method at room temperature. The obtained RA-loaded nanoparticles (NPs) were colloidally stable exhibiting average diameters in the range of 70–100 nm. RA was entrapped within the PLGA polymeric network with high encapsulation efficiencies and nanoparticles were able to release RA in a rate-controlled manner. A first-order equation model fitted our experimental data and confirmed the prevalence of diffusion mechanisms. Protein corona formation on the surface of NPs was assessed upon incubation with serum proteins. Protein adsorption induced an increase in the hydrodynamic diameter and a slight shift towards more negative surface charges of the NPs. The radical scavenging activity of RA-loaded NPs was also studied using the DPPH·assay and showed a dose–response relationship between the NPs concentration and DPPH inhibition. Finally, RA-loaded NPs did not affect the cellular proliferation of the human neuroblastoma SH-SY5Y cell line and promoted efficient cellular uptake. These results are promising for expanding the use of O/W nano-emulsions in biomedical applications.

Size-Selective Transfer of Lipid Nanoparticle-Based Drug Carriers Across the Blood Brain Barrier Via Vascular Occlusions Following Traumatic Brain Injury

The current lack of understanding about how nanocarriers cross the blood-brain barrier (BBB) in the healthy and injured brain is hindering the clinical translation of nanoscale brain-targeted drug-delivery systems. Here, the bio-distribution of lipid nano-emulsion droplets (LNDs) of two sizes (30 and 80 nm) in the mouse brain after traumatic brain injury (TBI) is investigated. The highly fluorescent LNDs are prepared by loading them with octadecyl rhodamine B and a bulky hydrophobic counter-ion, tetraphenylborate. Using in vivo two-photon and confocal imaging, the circulation kinetics and bio-distribution of LNDs in the healthy and injured mouse brain are studied. It is found that after TBI, LNDs of both sizes accumulate at vascular occlusions, where specifically 30 nm LNDs extravasate into the brain parenchyma and reach neurons. The vascular occlusions are not associated with bleedings, but instead are surrounded by processes of activated microglia, suggesting a specific opening of the BBB. Finally, correlative light-electron microscopy reveals 30 nm LNDs in endothelial vesicles, while 80 nm particles remain in the vessel lumen, indicating size-selective vesicular transport across the BBB via vascular occlusions. The data suggest that microvascular occlusions serve as "gates" for the transport of nanocarriers across the BBB.

Fluorescence labelled XT5 modified nano-capsules enable highly sensitive myeloma cells detection

Accurate diagnosis of cancer cells in early stages plays an important role in reliable therapeutic strategies. In this study, we aimed to develop fluorescence-conjugated polymer carrying nanocapsules (NCs) which is highly selective for myeloma cancer cells. To gain specific targeting properties, NCs, XT5 molecules (a benzamide derivative) which shows high affinity properties against protease-activated receptor-1 (PAR1), that overexpressed in myeloma cancer cells, was used. For this purpose, 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[carboxy(polyethylene glycol)-2000]-carboxylic acid (DSPE-PEG₂₀₀₀-COOH) molecules, as a main encapsulation material, was conjugated to XT5 molecules due to esterification reaction using N,N'-dicyclohexylcarbodiimide as a coupling agent. The synthesized DSPE-PEG₂₀₀₀-COO-XT5 was characterized by using FT-IR and¹H NMR spectroscopies and results indicated that XT5 molecules were successfully conjugated to DSPE-PEG₂₀₀₀-COOH. Poly(fluorene-alt-benzothiadiazole) (PFBT) conjugated polymer (CP) was encapsulated with DSPE-PEG₂₀₀₀-COO-XT5 due to dissolving in tetrahydrofuran and ultra-sonication in an aqueous solution, respectively. The morphological properties, UV-vis absorbance, and emission properties of obtainedCPencapsulatedDSPE-PEG₂₀₀₀-COO-XT5(CPDP-XT5) NCs was determined by utilizing scanning electron microscopy, UV-vis spectroscopy, and fluorescent spectroscopy, respectively. Cytotoxicity properties of CPDP-XT5 was evaluated by performing MTT assay on RPMI 8226 myeloma cell lines. Cell viability results confirmed that XT5 molecules were successfully conjugated to DSPE-PEG₂₀₀₀-COOH. Specific targeting properties of CPDP-XT5 NCs and XT5-free NCs (CPDP NCs) were investigated on RPMI 8226 myeloma cell lines by utilizing fluorescent microscopy and results indicated that CPDP-XT5 NCs shows significantly high affinity in comparison to CPDP NCs against the cells. Homology modeling and molecular docking properties of XT5 molecules were evaluated and simulation results confirmed our results.

Dynamic covalent chemistry in live cells for organelle targeting and enhanced photodynamic action

Organelle-specific targeting enables increasing the therapeutic index of drugs and localizing probes for better visualization of cellular processes. Current targeting strategies require conjugation of a molecule of interest with organelle-targeting ligands. Here, we propose a concept of dynamic covalent targeting of organelles where the molecule is conjugated with its ligand directly inside live cells through a dynamic covalent bond. For this purpose, we prepared a series of organelle-targeting ligands with a hydrazide residue for reacting with dyes and drugs bearing a ketone group. We show that dynamic hydrazone bond can be formed between these hydrazide ligands and a ketone-functionalized Nile Red dye (NRK) in situ in model lipid membranes or nanoemulsion droplets. Fluorescence imaging in live cells reveals that the targeting hydrazide ligands can induce preferential localization of NRK dye and an anti-cancer drug doxorubicin in plasma membranes, mitochondria and lipid droplets. Thus, with help of the dynamic covalent targeting, it becomes possible to direct a given bioactive molecule to any desired organelle inside the cell without its initial functionalization by the targeting ligand. Localizing the same NRK dye in different organelles by the hydrazide ligands is found to affect drastically its photodynamic activity, with the most pronounced phototoxic effects in mitochondria and plasma membranes. The capacity of this approach to tune biological activity of molecules can improve efficacy of drugs and help to understand better their intracellular mechanisms.

Review on Nanoparticles and Nanostructured Materials: Bioimaging, Biosensing, Drug Delivery, Tissue Engineering, Antimicrobial, and Agro-Food Applications

In the last few decades, the vast potential of nanomaterials for biomedical and healthcare applications has been extensively investigated. Several case studies demonstrated that nanomaterials can offer solutions to the current challenges of raw materials in the biomedical and healthcare fields. This review describes the different nanoparticles and nanostructured material synthesis approaches and presents some emerging biomedical, healthcare, and agro-food applications. This review focuses on various nanomaterial types (e.g., spherical, nanorods, nanotubes, nanosheets, nanofibers, core-shell, and mesoporous) that can be synthesized from different raw materials and their emerging applications in bioimaging, biosensing, drug delivery, tissue engineering, antimicrobial, and agro-foods. Depending on their morphology (e.g., size, aspect ratio, geometry, porosity), nanomaterials can be used as formulation modifiers, moisturizers, nanofillers, additives, membranes, and films. As toxicological assessment depends on sizes and morphologies, stringent regulation is needed from the testing of efficient nanomaterials dosages. The challenges and perspectives for an industrial breakthrough of nanomaterials are related to the optimization of production and processing conditions.

Fluorescence Correlation Spectroscopy Monitors the Fate of Degradable Nanocarriers in the Blood Stream

The use of nanoparticles as carriers to deliver pharmacologically active compounds to specific parts of the body via the bloodstream is a promising therapeutic approach for the effective treatment of various diseases. To reach their target sites, nanocarriers (NCs) need to circulate in the bloodstream for prolonged periods without aggregation, degradation, or cargo loss. However, it is very difficult to identify and monitor small-sized NCs and their cargo in the dense and highly complex blood environment. Here, we present a new fluorescence correlation spectroscopy-based method that allows the precise characterization of fluorescently labeled NCs in samples of less than 50 μL of whole blood. The NC size, concentration, and loading efficiency can be measured to evaluate circulation times, stability, or premature drug release. We apply the new method to follow the fate of pH-degradable fluorescent cargo-loaded nanogels in the blood of live mice for periods of up to 72 h.

Recent advances in the targeted delivery of paclitaxel nanomedicine for cancer therapy

Cancer cases have reached an all-time high in the current era.

Design of nanoemulgel using Argania spinosa microfibrillated cellulose and natural emulsifiers foreseeing melanogenesis enhancement

Nanotechnology is a route of choice that improves administration and efficacy of bioactive compounds. In this study, nanoemulgels were prepared using microfibrillated cellulose from Argania spinosa shell (AS-MFC) and Argan shell (ASE) or Argan press cake extracts (APC) as natural emulsifiers. Oil-in-water (O/W) nanoemulsions were prepared using different natural emulsifiers or synthetic emulsifiers and presented a nano size (d_3,2 < 140 nm). Following that, the nanoemulsions were incorporated within AS-MFC matrix and rheological properties confirmed a shear thinning behavior. Confocal micrographs of nanoemulgels confirmed the dispersion of nanoemulsions in the AS-MFC network without affecting the nanoemulsions stability. Finally, in vitro bioassay on B16F10 using ASE or APC nanoemulsions was conducted. This study confirmed cell permeation in B16F10 cells of formulated nanoemulsions and the upregulation of melanin content up to 30% more that the untreated cells. This study designed novel MFC nanoemulgel with high potential application in healthcare and cosmetic field.

Cytotoxicity of Amino-BODIPY Modulated via Conjugation with 2-Phenyl-3-Hydroxy-4(1H)-Quinolinones

The combination of cytotoxic amino-BODIPY dye and 2-phenyl-3-hydroxy-4(1H)-quinolinone (3-HQ) derivatives into one molecule gave rise to selective activity against lymphoblastic or myeloid leukemia and the simultaneous disappearance of the cytotoxicity against normal cells. Both species' conjugation can be realized via a disulfide linker cleavable in the presence of glutathione characteristic for cancer cells. The cleavage liberating the free amino-BODIPY dye and 3-HQ derivative can be monitored by ratiometric fluorescence or by the OFF-ON effect of the amino-BODIPY dye. A similar cytotoxic activity is observed when the amino-BODIPY dye and 3-HQ derivative are connected through a non-cleavable maleimide linker. The work reports the synthesis of several conjugates, the study of their cleavage inside cells, and cytotoxic screening.

Biodistribution of 68/67Ga-Radiolabeled Sphingolipid Nanoemulsions by PET and SPECT Imaging

Background and Purpose

Non-invasive imaging methodologies, especially nuclear imaging techniques, have undergone an extraordinary development over the last years. Interest in the development of innovative tracers has prompted the emergence of new nanomaterials with a focus on nuclear imaging and therapeutical applications. Among others, organic nanoparticles are of the highest interest due to their translational potential related to their biocompatibility and biodegradability. Our group has developed a promising new type of biocompatible nanomaterials, sphingomyelin nanoemulsions (SNs). The aim of this study is to explore the potential of SNs for nuclear imaging applications.

Methods

Ready-to-label SNs were prepared by a one-step method using lipid derivative chelators and characterized in terms of their physicochemical properties. Stability was assessed under storage and after incubation with human serum. Chelator-functionalized SNs were radiolabeled with ⁶⁷Ga and ⁶⁸Ga, and the radiochemical yield (RCY), radiochemical purity (RCP) and radiochemical stability (RCS) were determined. Finally, the biodistribution of ^67/68Ga-SNs was evaluated in vivo and ex vivo.

Results

Here, we describe a simple and mild one-step method for fast and efficient radiolabeling of SNs with ⁶⁸Ga and ⁶⁷Ga radioisotopes. In vivo experiments showed that ^67/68Ga-SNs can efficiently and indistinctly be followed up by PET and SPECT. Additionally, we proved that the biodistribution of the ^67/68Ga-SNs can be conveniently modulated by modifying the surface properties of different hydrophilic polymers, and therefore the formulation can be further adapted to the specific requirements of different biomedical applications.

Conclusion

This work supports ^67/68Ga-SNs as a novel probe for nuclear imaging with tunable biodistribution and with great potential for the future development of nanotheranostics.

Targeted Delivery of Drugs and Genes Using Polymer Nanocarriers for Cancer Therapy

Cancer is one of the primary causes of worldwide human deaths. Most cancer patients receive chemotherapy and radiotherapy, but these treatments are usually only partially efficacious and lead to a variety of serious side effects. Therefore, it is necessary to develop new therapeutic strategies. The emergence of nanotechnology has had a profound impact on general clinical treatment. The application of nanotechnology has facilitated the development of nano-drug delivery systems (NDDSs) that are highly tumor selective and allow for the slow release of active anticancer drugs. In recent years, vehicles such as liposomes, dendrimers and polymer nanomaterials have been considered promising carriers for tumor-specific drug delivery, reducing toxicity and improving biocompatibility. Among them, polymer nanoparticles (NPs) are one of the most innovative methods of non-invasive drug delivery. Here, we review the application of polymer NPs in drug delivery, gene therapy, and early diagnostics for cancer therapy.

Bulky Barbiturates as Non-Toxic Ionic Dye Insulators for Enhanced Emission in Polymeric Nanoparticles

Bulky hydrophobic counterions (weakly coordinating anions) can insulate ionic dyes against aggregation-caused quenching (ACQ) and enable preparation of highly fluorescent dye-loaded nanoparticles (NPs) for bioimaging, biosensing and light harvesting. Here, we introduce a family of hydrophobic anions based on fluorinated C-acyl barbiturates with delocalized negative charge and bulky non-polar groups. Similarly to fluorinated tetraphenylborates, these barbiturates prevent ACQ of cationic dye alkyl rhodamine B inside polymer NPs made of biodegradable poly(lactic-co-glycolic acid) (PLGA). Their efficiency to prevent ACQ increases for analogues with higher acidity and bulkiness. Their structure controls dye-dye communication, yielding bright NPs with on/off switching or stable emission. They enhance dye encapsulation inside NPs, allowing intracellular imaging without dye leakage. Compared to fluorinated tetraphenylborates known as cytotoxic transmembrane ion transporters, the barbiturates display a significantly lower cytotoxicity. These chemically available and versatile barbiturate derivatives are promising counterion scaffolds for preparation of bright non-toxic fluorescent nanomaterials.

Quantitative comparison of different fluorescent dye-loaded nanoparticles

Labeling nanoparticles with fluorescent dyes is a common approach to investigate their cell uptake and biodistribution, providing valuable information for the preclinical assessment of nanoparticles for drug delivery. However, the underlying assumption that the fluorescence intensity of dye-labeled nanoparticles correlates positively with the amount of nanoparticles taken up by cells might not be valid under some conditions, as it can be affected by many factors including dye dispersion, dye quenching, and material shading. Here we demonstrated that both nanoparticles with hydrophobic dyes encapsulated inside and nanoparticles with hydrophilic dyes conjugated on the particle surface suffer from different degrees of dye quenching, making it challenging for quantitative comparison of cell uptake of different nanoparticles. To address this challenge, we proposed a possible solution for direct comparative studies of dye-labeled nanoparticles. This work provides valuable information for designing and evaluating different nanoparticles for drug delivery applications.

Ultrabright Green-Emitting Nanoemulsions Based on Natural Lipids-BODIPY Conjugates

Nanoemulsions (NEs) are water-dispersed oil droplets that constitute stealth biocompatible nanomaterials. NEs can reach an impressive degree of fluorescent brightness owing to their oily core that can encapsulate a large number of fluorophores on the condition the latter are sufficiently hydrophobic and oil-soluble. BODIPYs are among the brightest green emitting fluorophores and as neutral molecules possess high lipophilicity. Herein, we synthesized three different natural lipid-BODIPY conjugates by esterification of an acidic BODIPY by natural lipids, namely: α-tocopherol (vitamin E), cholesterol, and stearyl alcohol. The new BODIPY conjugates were characterized in solvents and oils before being encapsulated in NEs at various concentrations. The physical (size, stability over time, leakage) and photophysical properties (absorption and emission wavelength, brightness, photostability) are reported and showed that the nature of the lipid anchor and the nature of the oil used for emulsification greatly influence the properties of the bright NEs.

NIR-/pH-Responsive Nanocarriers Based on Mesoporous Hollow Polydopamine for Codelivery of Hydrophilic/Hydrophobic Drugs and Photothermal Synergetic Therapy

Combined therapy system has become an efficient strategy to overcome drug resistance and strengthen therapeutic effects. Herein, an efficient NIR-/pH-triggered dual-drug-loaded nanoplatform was designed for combined chemo-photothermal therapy. The hydrophobic anticancer drug bortezomib (BTZ) was first loaded in mesoporous polydopamine nanospheres (MPDAs) through the acid-sensitive borate ester bond. Afterward, pH-responsive carboxymethyl chitosan (CMCS) conjugated on the surface of MPDA could capture another anticancer drug doxorubicin (DOX) and exhibited controlled release behavior in an acidic tumor microenvironment. Meanwhile, under NIR laser irradiation, hyperthermia produced by the photothermal conversion agent MPDA could efficiently ablate cancer cells and further promote drug release. In vitro and in vivo experiments emphasized that the synthesized MPDA-BTZ@CMCS-DOX nanostructure exhibited efficient accumulation in the tumor site, resulting in sustained release of BTZ and DOX and realizing NIR-/pH-triggered chemotherapy and photothermal synergistic ablation of cancer.

Development of Non-Porous Silica Nanoparticles towards Cancer Photo-Theranostics

Nanoparticles have demonstrated several advantages for biomedical applications, including for the development of multifunctional agents as innovative medicine. Silica nanoparticles hold a special position among the various types of functional nanoparticles, due to their unique structural and functional properties. The recent development of silica nanoparticles has led to a new trend in light-based nanomedicines. The application of light provides many advantages for in vivo imaging and therapy of certain diseases, including cancer. Mesoporous and non-porous silica nanoparticles have high potential for light-based nanomedicine. Each silica nanoparticle has a unique structure, which incorporates various functions to utilize optical properties. Such advantages enable silica nanoparticles to perform powerful and advanced optical imaging, from the in vivo level to the nano and micro levels, using not only visible light but also near-infrared light. Furthermore, applications such as photodynamic therapy, in which a lesion site is specifically irradiated with light to treat it, have also been advancing. Silica nanoparticles have shown the potential to play important roles in the integration of light-based diagnostics and therapeutics, termed "photo-theranostics". Here, we review the recent development and progress of non-porous silica nanoparticles toward cancer "photo-theranostics".