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Designing chromophores for biological applications requires a fundamental understanding of how the chemical structure of a chromophore influences its photophysical properties. We here describe the synthesis of a library of BODIPY dyes, exploring diversity at various positions around the BODIPY core. The results show that the nature and position of substituents have a dramatic effect on the spectroscopic properties. Substituting in a heavy atom or adjusting the size and orientation of a conjugated system provides a means of altering the spectroscopic profiles with high precision. The insight from the structure–activity relationship was applied to devise a new BODIPY dye with rationally designed photochemical properties including absorption towards the near-infrared region. The dye also exhibited switch-on fluorescence to enable visualisation of cells with high signal-to-noise ratio without washing-out of unbound dye. The BODIPY-based probe is non-cytotoxic and compatible with staining procedures including cell fixation and immunofluorescence microscopy.

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We are witnessing an exponential increase in the use of different nanomaterials in a plethora of biomedical fields. We are all aware of how nanoparticles (NPs) have influenced and revolutionized the way we supply drugs or how to use them as therapeutic agents thanks to their tunable physico-chemical properties. However, there is still a niche of applications where NP have not yet been widely explored. This is the field of ocular delivery and NP-based therapy, which characterizes the topic of the current review. In particular, many efforts are being made to develop nanosystems capable of reaching deeper sections of the eye such as the retina. Particular attention will be given here to noble metal (gold and silver), and to polymeric nanoparticles, systems consisting of lipid bilayers such as liposomes or vesicles based on nonionic surfactant. We will report here the most relevant literature on the use of different types of NPs for an efficient delivery of drugs and bio-macromolecules to the eyes or as active therapeutic tools.

JTD Keywords: Bio-inspired NPs, Drug delivery, Noble metals NPs, Retinal diseases

The blood-brain barrier is made of polarized brain endothelial cells (BECs) phenotypically conditioned by the central nervous system (CNS). Although transport across BECs is of paramount importance for nutrient uptake as well as ridding the brain of waste products, the intracellular sorting mechanisms that regulate successful receptor-mediated transcytosis in BECs remain to be elucidated. Here, we used a synthetic multivalent system with tunable avidity to the low-density lipoprotein receptor–related protein 1 (LRP1) to investigate the mechanisms of transport across BECs. We used a combination of conventional and super-resolution microscopy, both in vivo and in vitro, accompanied with biophysical modeling of transport kinetics and membrane-bound interactions to elucidate the role of membrane-sculpting protein syndapin-2 on fast transport via tubule formation. We show that high-avidity cargo biases the LRP1 toward internalization associated with fast degradation, while mid-avidity augments the formation of syndapin-2 tubular carriers promoting a fast shuttling across.

JTD

Mononuclear phagocytes such as monocytes, tissue-specific macrophages, and dendritic cells are primary actors in both innate and adaptive immunity. These professional phagocytes can be parasitized by intracellular bacteria, turning them from housekeepers to hiding places and favoring chronic and/or disseminated infection. One of the most infamous is the bacteria that cause tuberculosis (TB), which is the most pandemic and one of the deadliest diseases, with one-third of the world’s population infected and an average of 1.8 million deaths/year worldwide. Here we demonstrate the effective targeting and intracellular delivery of antibiotics to infected macrophages both in vitro and in vivo, using pH-sensitive nanoscopic polymersomes made of PMPC–PDPA block copolymer. Polymersomes showed the ability to significantly enhance the efficacy of the antibiotics killing Mycobacterium bovis, Mycobacterium tuberculosis, and another established intracellular pathogen, Staphylococcus aureus. Moreover, they demonstrated to easily access TB-like granuloma tissues—one of the harshest environments to penetrate—in zebrafish models. We thus successfully exploited this targeting for the effective eradication of several intracellular bacteria, including M. tuberculosis, the etiological agent of human TB.

JTD

Background: The developing zebrafish is an emerging tool in nanomedicine, allowing non-invasive live imaging of the whole animal at higher resolution than is possible in the more commonly used mouse models. In addition, several transgenic fish lines are available endowed with selected cell types expressing fluorescent proteins; this allows nanoparticles to be visualized together with host cells. Methods: Here, we introduce the zebrafish neural tube as a robust injection site for cancer cells, excellently suited for high resolution imaging. We use light and electron microscopy to evaluate cancer growth and to follow the fate of intravenously injected nanoparticles. Findings: Fluorescently labelled mouse melanoma B16 cells, when injected into this structure proliferated rapidly and stimulated angiogenesis of new vessels. In addition, macrophages, but not neutrophils, selectively accumulated in the tumour region. When injected intravenously, nanoparticles made of Cy5-labelled poly(ethylene glycol)-block-poly(2-(diisopropyl amino) ethyl methacrylate) (PEG-PDPA) selectively accumulated in the neural tube cancer region and were seen in individual cancer cells and tumour associated macrophages. Moreover, when doxorubicin was released from PEG-PDPA, in a pH dependant manner, these nanoparticles could strongly reduce toxicity and improve the treatment outcome compared to the free drug in zebrafish xenotransplanted with mouse melanoma B16 or human derived melanoma cells. Interpretation: The zebrafish has the potential of becoming an important intermediate step, before the mouse model, for testing nanomedicines against patient-derived cancer cells.

JTD

We investigated how the shape of polymeric vesicles, made by the exact same material, impacts the replication activity and metabolic state of both cancer and non-cancer cell types. First, we isolated discrete geometrical structures (spheres and tubes) from a heterogeneous sample using density-gradient centrifugation. Then, we characterized the cellular internalization and the kinetics of uptake of both types of polymersomes in different cell types (either cancer or non-cancer cells). We also investigated the cellular metabolic response as a function of the shape of the structures internalized and discovered that tubular vesicles induce a significant decrease in the replication activity of cancer cells compared to spherical vesicles. We related this effect to the significant up-regulation of the tumor suppressor genes p21 and p53 with a concomitant activation of caspase 3/7. Finally, we demonstrated that combining the intrinsic shape-dependent effects of tubes with the delivery of doxorubicin significantly increases the cytotoxicity of the system. Our results illustrate how the geometrical conformation of nanoparticles could impact cell behavior and how this could be tuned to create novel drug delivery systems tailored to specific biomedical application.

JTD

The possibility of exploring basic biological phenomena requires the development of new and efficient bio-imaging tools. These should ideally combine the feasibility of production (potentially through the use of green chemistry) together with high targeting efficiency, low cytotoxicity, and optimal contrast characteristics. In this work, we developed nanovesicles based on cardanol, a natural and renewable byproduct of the cashew industry, and a fluorescent reporter was encapsulated in them through an environment-friendly synthesis method. In vitro investigations demonstrated that the cardanol nanovesicles are efficiently taken-up by both professional and non-professional phagocytic cells, which have been modeled in our approach by macrophages and HeLa cells, respectively. Co-localization studies show high affinity of the nanovesicles towards the cell plasma membrane. Moreover, metabolic assays confirmed that these nanostructures are biocompatible in a specific concentration range, and do not promote inflammation response in human macrophages. Stability studies carried out at different temperatures showed that the nanovesicles are stable at both 37 °C and 20 °C, while the formation of aggregates occurs when the nanodispersion is incubated at 4 °C. The results demonstrate the high potential of fluorescent cardanol nanovesicles as a green bioimaging tool, especially for investigating cell membrane dynamics.

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The synthesis and aqueous self-assembly of a new class of amphiphilic aliphatic polyesters are presented. These AB block polyesters comprise polycaprolactone (hydrophobe) and an alternating polyester from succinic acid and an ether substituted epoxide (hydrophile). They self-assemble into biodegradable polymersomes capable of entering cells. Their degradation products are bioactive giving rise to differentiated cellular responses inducing stromal cell proliferation and macrophage apoptosis. Both effects emerge only when the copolymers enter cells as polymersomes and their magnitudes are size dependent.

JTD

Glucocorticoid (GC) drugs are the cornerstone therapy used in the treatment of inflammatory diseases. Here, we report pH responsive poly(2-methacryloyloxyethyl phosphorylcholine)–poly(2-(diisopropylamino)ethyl methacrylate) (PMPC–PDPA) polymersomes as a suitable nanoscopic carrier to precisely and controllably deliver GCs within inflamed target cells. The in vitro cellular studies revealed that polymersomes ensure the stability, selectivity and bioavailability of the loaded drug within macrophages. At molecular level, we tested key inflammation-related markers, such as the nuclear factor-κB, tumour necrosis factor-α, interleukin-1β, and interleukin-6. With this, we demonstrated that pH responsive polymersomes are able to enhance the anti-inflammatory effect of loaded GC drug. Overall, we prove the potential of PMPC–PDPA polymersomes to efficiently promote the inflammation shutdown, while reducing the well-known therapeutic limitations in GC-based therapy.

JTD Keywords: Inflammation, Macrophages, Glucocorticoid, Polymersomes

The green synthesis of nanoparticles (NPs) is currently under worldwide investigation as an eco-friendly alternative to traditional routes (NPs): the absence of toxic solvents and catalysts make it suitable in the design of promising nanomaterials for nanomedicine applications. In this work, we used the extracts collected from leaves of two cultivars (Leccino and Carolea) belonging to the species Olea Europaea, to synthesize silver NPs (AgNPs) in different pH conditions and low temperature. NPs underwent full morphological characterization with the aim to define a suitable protocol to obtain a monodispersed population of AgNPs. Afterwards, to validate the reproducibility of the mentioned synthetic procedure, we moved on to another Mediterranean plant, the Laurus Nobilis. Interestingly, the NPs obtained using the two olive cultivars produced NPs with different shape and size, strictly depending on the cultivar selected and pH. Furthermore, the potential ability to inhibit the growth of two woman cancer cells (breast adenocarcinoma cells, MCF-7 and human cervical epithelioid carcinoma, HeLa) were assessed for these AgNPs, as well as their capability to mitigate the bacteria concentration in samples of contaminated well water. Our results showed that toxicity was stronger when MCF-7 and Hela cells were exposed to AgNPs derived from Carolea obtained at pH 7 presenting irregular shape; on the other hand, greater antibacterial effect was revealed using AgNPs obtained at pH 8 (smaller and monodispersed) on well water, enriched with bacteria and coliforms.

JTD Keywords: Green synthesis, Silver nanoparticles, Olea Europaea, Leccino, Carolea, Cytotoxicity, Genotoxicity, Antibacterial activity

The nowadays growing use of nanoparticles (NPs) in commercial products does not match a comprehensive understanding of their potential harmfulness. More in vitro investigations are required to address how the physicochemical properties of NPs guide their engulfment within cells and their intracellular trafficking, fate, and toxicity. These nano-bio interactions have not been extensively addressed yet, especially from a mechanical viewpoint. Cell mechanic is a critical indicator of cell health because it regulates processes like cell migration, tissue integrity, and differentiation via cytoskeleton rearrangements. Here, we investigated in vitro the elasticity perturbation of Caco-2 and A549 cell lines, in terms of Young’s modulus modification induced by SiO2NPS and TiO2NPS. TiO2NPs demonstrated stronger effects on cell elasticity compared to SiO2NPs, as they induced significant morphological and morphometric changes in actin network. TiO2NPS increased the elasticity in Caco-2 cells, while opposite effects have been observed on A549 cells. These results demonstrate the existence of a correlation between the alteration of cell elasticity and NPs toxicity that depends, in turn, on the NPs physicochemical properties and the specific cell tested.

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