TAT and HA2 facilitate cellular uptake of gold nanoparticles but do not lead to cytosolic localisation

Bioproduced Nanoparticles Deliver Multiple Cargoes via Targeted Tumor Therapy In Vivo

This study recognized biologically produced gold nanoparticles (AuNPs) as multiple cargo carriers with a perspective of drug delivery into specialized tumor cells in vivo. Paclitaxel (PTX), transferrin, and antimiR-135b were conjugated with AuNPs and their uptake by mouse tumor cells in an induced breast cancer model was investigated. Each of the above-mentioned molecules was conjugated to the AuNPs separately as well as simultaneously, loading efficiency of each cargo was assessed, and performance of the final product (FP) was judged. After tumor induction in BALB/c mice, sub-IC50 doses of FP as well as control AuNPs, PTX, and phosphate buffered saline were administered in vivo. Round AuNPs were prepared using Fusarium oxysporum and exhibited a size of 13 ± 1.3 nm and a zeta potential of -35.8 ± 1.3 mV. The cytotoxicity of individual conjugates and FP were tested by MTT assay in breast tumor cells 4T1 and nontumor fibroblasts NIH/3T3 cells. The conjugation of individual molecules with AuNPs was confirmed, and FP (size of 54 ± 14 nm and zeta potential of -31.9 ± 2.08 mV) showed higher 4T1-specific toxicity in vitro when compared to control conjugates. After in vivo application of the FP, transmission electron microscopy analyses proved the presence of AuNPs in the tumor cells. Hematoxylin and eosin staining of the tumor tissue revealed that the FP group exhibited the highest amounts of inflammatory, necrotic, and apoptotic cells in contrast to the control groups. Finally, qPCR results showed that FP could transfect and suppress miR-135b expression in vivo, confirming the tumor-targeting properties of FP. The capacity of biologically produced gold nanoparticles to conjugate with multiple decorative molecules while retaining their stability and effective intracellular uptake makes them a promising alternative strategy superior to current drug carriers.

Therapeutic Oligonucleotides: An Outlook on Chemical Strategies to Improve Endosomal Trafficking

The potential of oligonucleotide therapeutics is undeniable as more than 15 drugs have been approved to treat various diseases in the liver, central nervous system (CNS), and muscles. However, achieving effective delivery of oligonucleotide therapeutics to specific tissues still remains a major challenge, limiting their widespread use. Chemical modifications play a crucial role to overcome biological barriers to enable efficient oligonucleotide delivery to the tissues/cells of interest. They provide oligonucleotide metabolic stability and confer favourable pharmacokinetic/pharmacodynamic properties. This review focuses on the various chemical approaches implicated in mitigating the delivery problem of oligonucleotides and their limitations. It highlights the importance of linkers in designing oligonucleotide conjugates and discusses their potential role in escaping the endosomal barrier, a bottleneck in the development of oligonucleotide therapeutics.

Unravelling cytosolic delivery of cell penetrating peptides with a quantitative endosomal escape assay

Cytosolic transport is an essential requirement but a major obstacle to efficient delivery of therapeutic peptides, proteins and nucleic acids. Current understanding of cytosolic delivery mechanisms remains limited due to a significant number of conflicting reports, which are compounded by low sensitivity and indirect assays. To resolve this, we develop a highly sensitive Split Luciferase Endosomal Escape Quantification (SLEEQ) assay to probe mechanisms of cytosolic delivery. We apply SLEEQ to evaluate the cytosolic delivery of a range of widely studied cell-penetrating peptides (CPPs) fused to a model protein. We demonstrate that positively charged CPPs enhance cytosolic delivery as a result of increased non-specific cell membrane association, rather than increased endosomal escape efficiency. These findings transform our current understanding of how CPPs increase cytosolic delivery. SLEEQ is a powerful tool that addresses fundamental questions in intracellular drug delivery and will significantly improve the way materials are engineered to increase therapeutic delivery to the cytosol.

Efficient intracellular delivery of p53 protein by engineered protein crystals restores tumor suppressing function in vivo

Direct delivery of proteins into cells holds significant potential for basic research and drug development. However, the poor endosomal escape of conventional delivery strategies remains a challenge, thus limiting the clinical translation of many protein therapeutics. Herein, we report that engineered Cry3Aa protein (Pos3Aa) crystals formed naturally within Bacillus thuringiensis can serve as a vehicle for efficient cytosolic delivery of bioactive proteins. We showed that Pos3Aa-mediated delivery of tumor suppressor p53 protein, a promising therapeutic candidate found to be inactivated in nearly half of human cancers, resulted in the restoration of p53 function in p53-deficient cancer cells, and thereby sensitized them to 5-fluorouracil chemotherapy as demonstrated in in vitro and in vivo models. Our results validate that Pos3Aa crystals can be a robust and effective platform for the cytosolic delivery of effector proteins, and suggest that efficient uptake and endosomal escape could be critical for efficacious p53 protein-based cancer therapy.

Biomedical applications of the peptide decorated gold nanoparticles

Currently, peptide-nanoparticle (NP) conjugates have been demonstrated to be efficient and powerful tools for the treatment and the diagnosis of various diseases as well as in the bioimaging application. Several bioconjugation strategies have been adopted to formulate the peptide-NP conjugates. In this review, we discuss the exciting applications of peptide-gold (Au) NP conjugates in the area of drug delivery, targeting, cancer therapy, brain diseases, vaccines, immune modulation, biosensor, colorimetric detection of heavy metals, and bio-labeling in vitro and in vivo models. Within this framework, various approaches such as radiotherapy, photothermal therapy, photodynamic therapy and chemo-photothermal therapy have been demonstrated for the treatment of several diseases. Moreover, we highlight how the morphology, size, density of peptide and the protein corona influence the biological activity, biodistribution and biological fate of peptide-AuNP conjugates. In the end, we discuss the future outlook and the challenges being faced in the clinical translation of the peptide-AuNP conjugates. Overall, this review emphasizes that the peptide-AuNP conjugates might be used as potential theranostic agents for the treatment of life-threatening diseases in an economical fashion in the future.

Why have nanotechnologies been underutilized in the global uprising against the coronavirus pandemic?

Prior research on nanotechnologies in diagnostics, prevention and treatment of coronavirus infections is reviewed. Gold nanoparticles and semiconductor quantum dots in colorimetric and immunochromatographic assays, silica nanoparticles in the polymerase chain reaction and spike protein nanospheres as antigen carriers and adjuvants in vaccine formulations present notable examples in diagnostics and prevention, while uses of nanoparticles in coronavirus infection treatments have been merely sporadic. The current absence of antiviral therapeutics that specifically target human coronaviruses, including SARS-CoV-2, might be largely due to the underuse of nanotechnologies. Elucidating the interface between nanoparticles and coronaviruses is timely, but presents the only route to the rational design of precisely targeted therapeutics for coronavirus infections. Such a fundamental approach is also a viable prophylaxis against future pandemics of this type.

Gold Nanoparticles in Conjunction with Nucleic Acids as a Modern Molecular System for Cellular Delivery

Development of nanotechnology has become prominent in many fields, such as medicine, electronics, production of materials, and modern drugs. Nanomaterials and nanoparticles have gained recognition owing to the unique biochemical and physical properties. Considering cellular application, it is speculated that nanoparticles can transfer through cell membranes following different routes exclusively owing to their size (up to 100 nm) and surface functionalities. Nanoparticles have capacity to enter cells by themselves but also to carry other molecules through the lipid bilayer. This quality has been utilized in cellular delivery of substances like small chemical drugs or nucleic acids. Different nanoparticles including lipids, silica, and metal nanoparticles have been exploited in conjugation with nucleic acids. However, the noble metal nanoparticles create an alternative, out of which gold nanoparticles (AuNP) are the most common. The hybrids of DNA or RNA and metal nanoparticles can be employed for functional assemblies for variety of applications in medicine, diagnostics or nano-electronics by means of biomarkers, specific imaging probes, or gene expression regulatory function. In this review, we focus on the conjugates of gold nanoparticles and nucleic acids in the view of their potential application for cellular delivery and biomedicine. This review covers the current advances in the nanotechnology of DNA and RNA-AuNP conjugates and their potential applications. We emphasize the crucial role of metal nanoparticles in the nanotechnology of nucleic acids and explore the role of such conjugates in the biological systems. Finally, mechanisms guiding the process of cellular intake, essential for delivery of modern therapeutics, will be discussed.

Chlorambucil Conjugated Ugi Dendrimers with PAMAM-NH₂ Core and Evaluation of Their Anticancer Activity

Herein, a new Ugi multicomponent reaction strategy is described to enhance activity and solubility of the chemotherapeutic drug chlorambucil through its conjugation to poly(amidoamine) (PAMAM-NH₂) dendrimers with the simultaneous introduction of lipidic (i-Pr) and cationic (⁻NH₂) or anionic (⁻COOH) groups. Standard viability assays were used to evaluate the anticancer potential of the water-soluble dendrimers against PC-3 prostate and HT-29 colon cancer cell lines, as well as non-cancerous mouse NIH3T3 fibroblasts. It could be demonstrated that the anticancer activity against PC-3 cells was considerably improved when both chlorambucil and ⁻NH₂ (cationic) groups were present on the dendrimer surface (1b). Additionally, this dendrimer showed activity only against the prostate cancer cells (PC-3), while it did not affect colon cancer cells and fibroblasts significantly. The cationic chlorambucil-dendrimer 1b blocks PC-3 cells in the G2/M phase and induces caspase independent apoptosis.

Tumor heterogeneity and nanoparticle-mediated tumor targeting: the importance of delivery system personalization

After the discovery of the enhanced permeability and retention effect in 1986, it was envisioned that nanoparticle-mediated tumor-targeted delivery of chemotherapeutics would make a radical change in cancer therapy. However, after three decades of extensive research, only a few nanotherapeutics have been approved for clinical use. Although significant advantages of nanomedicines have been demonstrated in pre-clinical studies, clinical outcome was found to be variable. Advanced research has revealed that significant biochemical and structural variations exist between (and among) different tumors. These variations can considerably affect the tumor delivery and efficacy of nanomedicines. Tumor penetration is an important determining factor for positive therapeutic outcome and same nanomedicine can show diverse efficacy against different tumors depending on the extent of tumor accumulation and penetration. Recent research has started shading light on how the tumor variations can influence nanoparticle tumor delivery. These findings indicate that there is no "ideal" design of nanoparticles for exhibiting equally high efficacy against a broad spectrum of tumors. For achieving maximum benefit of the nanotherapeutics, it is necessary to analyze the tumor microenvironment for understanding the biological and structural characteristics of the tumor. Designing of the nanomedicine should be done according to the tumor characteristics. In this comprehensive review, we have first given a brief overview of the design characteristics of nanomedicine which impact their tumor delivery. Then we discussed about the variability in the tumor architecture and how it influences nanomedicine delivery. Finally, we have discussed the possibility of delivery system personalization based on the tumor characteristics.

Peptide and protein nanoparticle conjugates: versatile platforms for biomedical applications

Peptide- and protein-nanoparticle conjugates have emerged as powerful tools for biomedical applications, enabling the treatment, diagnosis, and prevention of disease. In this review, we focus on the key roles played by peptides and proteins in improving, controlling, and defining the performance of nanotechnologies. Within this framework, we provide a comprehensive overview of the key sequences and structures utilised to provide biological and physical stability to nano-constructs, direct particles to their target and influence their cellular and tissue distribution, induce and control biological responses, and form polypeptide self-assembled nanoparticles. In doing so, we highlight the great advances made by the field, as well as the challenges still faced in achieving the clinical translation of peptide- and protein-functionalised nano-drug delivery vehicles, imaging species, and active therapeutics.

Particle size affects the cytosolic delivery of membranotropic peptide-functionalized platinum nanozymes

Delivery of therapeutic agents inside the cytosol, avoiding the confinement in endo-lysosomal compartments and their degradative environment, is one of the key targets of nanomedicine to gain the maximum remedial effects. Current approaches based on cell penetrating peptides (CPPs), despite improving the cellular uptake efficiency of nanocarriers, have shown controversial results in terms of intracellular localization. To elucidate the delivery potential of CPPs, in this work we analyzed the role of the particle size in influencing the ability of a membranotropic peptide, namely gH625, to escape the endo-lysosomal pathway and deliver the particles in the cytosol. To this aim, we carried out a systematic assessment of the cellular uptake and distribution of monodisperse platinum nanoparticles (PtNPs), having different diameters (2.5, 5 and 20 nm) and citrate capping or gH625 peptide functionalization. The presence of gH625 significantly increased the amount of internalized NPs in human cervix epithelioid carcinoma cells, as a function of particle size. However, scanning transmission electron microscopy (STEM) and electron tomography (ET) revealed a prevalent confinement of PtNPs within vesicular structures, regardless of the particle size and surface functionalization. Only in the case of the smallest 2.5 nm particles, the membranotropic peptide was able to partly maintain its functionality, enabling cytosolic delivery of a small fraction of internalized PtNPs, though particle agglomeration in culture medium limited single-particle transport across the cell membrane. Interestingly, membrane crossing by 2.5 nm functionalized-PtNPs seemed to occur by diffusion through the lipid bilayer, with no apparent membrane damage. For larger particle sizes (≥5 nm), their hindrance likely blocked the membranotropic mechanism. Combining the enhanced uptake and partial cytosolic delivery promoted by gH625, we were able to achieve a strong improvement of the antioxidant nanozyme function of 2.5 nm PtNPs, decreasing both the endogenous ROS level and its overproduction following an external oxidative insult.

Endolysosomal targeting of a clinical chlorin photosensitiser for light-triggered delivery of nano-sized medicines

A major problem with many promising nano-sized biotherapeutics including macromolecules is that owing to their size they are subject to cellular uptake via endocytosis, and become entrapped and then degraded within endolysosomes, which can significantly impair their therapeutic efficacy. Photochemical internalisation (PCI) is a technique for inducing cytosolic release of the entrapped agents that harnesses sub-lethal photodynamic therapy (PDT) using a photosensitiser that localises in endolysosomal membranes. Using light to trigger reactive oxygen species-mediated rupture of the photosensitised endolysosomal membranes, the spatio-temporal selectivity of PCI then enables cytosolic release of the agents at the selected time after administration so that they can reach their intracellular targets. However, conventional photosensitisers used clinically for PDT are ineffective for photochemical internalisation owing to their sub-optimal intracellular localisation. In this work we demonstrate that such a photosensitiser, chlorin e6, can be repurposed for PCI by conjugating the chlorin to a cell penetrating peptide, using bioorthogonal ligation chemistry. The peptide conjugation enables targeting of endosomal membranes so that light-triggered cytosolic release of an entrapped nano-sized cytotoxin can be achieved with consequent improvement in cytotoxicity. The photoproperties of the chlorin moiety are also conserved, with comparable singlet oxygen quantum yields found to the free chlorin.

Plasmonic labeling of subcellular compartments in cancer cells: multiplexing with fine-tuned gold and silver nanoshells

Fine-tuned gold and silver nanoshells were produced via an entirely reformulated synthesis. The new method yielded ultramonodisperse samples, with polydispersity indexes (PI) as low as 0.02 and narrow extinction bands suited for multiplex analysis. A library of nanoshell samples with localized surface plasmon resonances (LSPR) spanning across the visible range was synthesized. Hyperspectral analysis revealed that the average scattering spectrum of 100 nanoshells matched closely to the spectrum of a single nanoshell, indicating an unprecedented low level of nanoparticle-to-nanoparticle variation for this type of system. A cell labeling experiment, targeting different subcellular compartments in MCF-7 human breast cancer cells, demonstrated that these monodisperse nanoparticles can be used as a multiplex platform for single cell analysis at the intracellular and extracellular level. Antibody-coated gold nanoshells targeted the plasma membrane, while silver nanoshells coated with a nuclear localization signal (NLS) targeted the nuclear membrane. A fluorescence counterstaining experiment, as well as single cell hyperspectral microscopy showed the excellent selectivity and specificity of each type of nanoparticle for its designed subcellular compartment. A time-lapse photodegradation experiment confirmed the enhanced stability of the nanoshells over fluorescent labeling and their capabilities for long-term live cell imaging.

Binding and Uptake into Human Hepatocellular Carcinoma Cells of Peptide-Functionalized Gold Nanoparticles

One of the most daunting challenges of nanomedicine is the finding of appropriate targeting agents to deliver suitable payloads precisely to cells affected by malignancies. Even more complex is the ability to ensure that the nanosystems enter those cells. Here, we use 2 nm (metal core) gold nanoparticles to target human hepatocellular carcinoma (HepG2) cells stably transfected with the SERPINB3 (SB3) protein. The nanoparticles were coated with a 85:15 mixture of thiols featuring, respectively, a phosphoryl choline (to ensure water solubility and biocompatibility) and a 28-mer peptide corresponding to the amino acid sequence 21-47 of the hepatitis B virus-PreS1 protein (PreS1(21-47)). Conjugation of the peptide was performed via the maleimide-thiol reaction in methanol, allowing the use of a limited amount of the targeting molecule. This is an efficient procedure also in the perspective of selecting libraries of new targeting agents. The rationale behind the selection of the peptide is that SB3, which is undetectable in normal hepatocytes, is overexpressed in hepatocellular carcinoma and in hepatoblastoma and has been proposed as a target of the hepatitis B virus (HBV). For the latter, the key recognition element is the PreS1(21-47) peptide, which is a fragment of one of the proteins composing the viral envelope. The ability of the conjugated nanoparticles to bind the target protein SB3, expressed in liver cancer cells, was investigated by surface plasmon resonance analysis and in vitro via cellular uptake analysis followed by atomic absorption analysis of digested samples. The results showed that the PreS1(21-47) peptide is a suitable targeting agent for cells overexpressing the SB3 protein. Even more important is the evidence that the gold nanoparticles are internalized by the cells. The comparison between the surface plasmon resonance analysis and the cellular uptake studies suggests that the presentation of the protein on the cell surface is critical for efficient recognition.

In Vivo Bio-distribution and Efficient Tumor Targeting of Gelatin/Silica Nanoparticles for Gene Delivery

The non-viral gene delivery system is an attractive alternative to cancer therapy. The clinical success of non-viral gene delivery is hampered by transfection efficiency and tumor targeting, which can be individually overcome by addition of functional modules such as cell penetration or targeting. Here, we first engineered the multifunctional gelatin/silica (GS) nanovectors with separately controllable modules, including tumor-targeting aptamer AGRO100, membrane-destabilizing peptide HA2, and polyethylene glycol (PEG), and then studied their bio-distribution and in vivo transfection efficiencies by contrast resonance imaging (CRI). The results suggest that the sizes and zeta potentials of multifunctional gelatin/silica nanovectors were 203-217 nm and 2-8 mV, respectively. Functional GS-PEG nanoparticles mainly accumulated in the liver and tumor, with the lowest uptake by the heart and brain. Moreover, the synergistic effects of tumor-targeting aptamer AGRO100 and fusogenic peptide HA2 promoted the efficient cellular internalization in the tumor site. More importantly, the combined use of AGRO100 and PEG enhanced tumor gene expression specificity and effectively reduced toxicity in reticuloendothelial system (RES) organs after intravenous injection. Additionally, low accumulation of GS-PEG was observed in the heart tissues with high gene expression levels, which could provide opportunities for non-invasive gene therapy.

Quantitative uptake of colloidal particles by cell cultures

The use of nanotechnologies involving nano- and microparticles has increased tremendously in the recent past. There are various beneficial characteristics that make particles attractive for a wide range of technologies. However, colloidal particles on the other hand can potentially be harmful for humans and environment. Today, complete understanding of the interaction of colloidal particles with biological systems still remains a challenge. Indeed, their uptake, effects, and final cell cycle including their life span fate and degradation in biological systems are not fully understood. This is mainly due to the complexity of multiple parameters which need to be taken in consideration to perform the nanosafety research. Therefore, we will provide an overview of the common denominators and ideas to achieve universal metrics to assess their safety. The review discusses aspects including how biological media could change the physicochemical properties of colloids, how colloids are endocytosed by cells, how to distinguish between internalized versus membrane-attached colloids, possible correlation of cellular uptake of colloids with their physicochemical properties, and how the colloidal stability of colloids may vary upon cell internalization. In conclusion three main statements are given. First, in typically exposure scenarios only part of the colloids associated with cells are internalized while a significant part remain outside cells attached to their membrane. For quantitative uptake studies false positive counts in the form of only adherent but not internalized colloids have to be avoided. pH sensitive fluorophores attached to the colloids, which can discriminate between acidic endosomal/lysosomal and neutral extracellular environment around colloids offer a possible solution. Second, the metrics selected for uptake studies is of utmost importance. Counting the internalized colloids by number or by volume may lead to significantly different results. Third, colloids may change their physicochemical properties along their life cycle, and appropriate characterization is required during the different stages.

Intranasal Delivery of Recombinant AAV Containing BDNF Fused with HA2TAT: a Potential Promising Therapy Strategy for Major Depressive Disorder

Depression is a disturbing psychiatric disease with unsatisfied therapy. Not all patients are sensitive to anti-depressants currently in use, side-effects are unavoidable during therapy, and the cases with effectiveness are always accompanied with delayed onset of clinical efficacy. Delivering brain-derived neurotrophic factor (BDNF) to brain seems to be a promising therapy. However, a better approach to delivery is still rudimentary. The purpose of our present work is to look for a rapid-onset and long-lasting therapeutic strategy for major depressive disorder (MDD) by effectively delivering BDNF to brain. BDNF, fused with cell-penetrating peptides (TAT and HA2), was packaged in adenovirus associated virus (AAV) to construct the BDNF-HA2TAT/AAV for intranasally delivering BDNF to central nervous system (CNS) via nose-brain pathway. Intranasal administration of BDNF-HA2TAT/AAV to normal mice displayed anti-depression effect in forced swimming test when the delivery lasted relatively longer. The AAV applied to mice subjected to chronic mild stress (CMS) through intranasal administration for 10 days also alleviated depression-like behaviors. Western-blotting analysis revealed that BDNF-HA2TAT/AAV nasal administration enhanced hippocampal BDNF content. These results indicate intranasal administration of constructed BDNF-HA2TAT/AAV exerts anti-depression effect in CMS mice by increasing hippocampal BDNF, suggesting that this strategy holds a promising therapeutic potential for MDD.

Platinum nanozymes recover cellular ROS homeostasis in an oxidative stress-mediated disease model

In recent years, the use of nanomaterials as biomimetic enzymes has attracted great interest. In this work, we show the potential of biocompatible platinum nanoparticles (Pt NPs) as antioxidant nanozymes, which combine abundant cellular internalization and efficient scavenging activity of cellular reactive oxygen species (ROS), thus simultaneously integrating the functions of nanocarriers and antioxidant drugs. Careful toxicity assessment and intracellular tracking of Pt NPs proved their cytocompatibility and high cellular uptake, with compartmentalization within the endo/lysosomal vesicles. We have demonstrated that Pt NPs possess strong and broad antioxidant properties, acting as superoxide dismutase, catalase, and peroxidase enzymes, with similar or even superior performance than natural enzymes, along with higher adaptability to the changes in environmental conditions. We then exploited their potent activity as radical scavenging materials in a cellular model of an oxidative stress-related disorder, namely human Cerebral Cavernous Malformation (CCM) disease, which is associated with a significant increase in intracellular ROS levels. Noteworthily, we found that Pt nanozymes can efficiently reduce ROS levels, completely restoring the cellular physiological homeostasis.