Peptides and proteins used to enhance gold nanoparticle delivery to the brain: preclinical approaches

Advances in nanotechnology-assisted photodynamic therapy for neurological disorders: a comprehensive review

Neurological disorders such as neurodegenerative diseases and nervous system tumours affect more than one billion people throughout the globe. The physiological sensitivity of the nervous tissue limits the application of invasive therapies and leads to poor treatment and prognosis. One promising solution that has generated attention is Photodynamic therapy (PDT), which can potentially revolutionise the treatment landscape for neurological disorders. PDT attracted substantial recognition for anticancer efficacy and drug conjugation for targeted drug delivery. This review thoroughly explained the basic principles of PDT, scientific interventions and advances in PDT, and their complicated mechanism in treating brain-related pathologies. Furthermore, the merits and demerits of PDT in the context of neurological disorders offer a well-rounded perspective on its feasibility and challenges. In conclusion, this review encapsulates the significant potential of PDT in transforming the treatment landscape for neurological disorders, emphasising its role as a non-invasive, targeted therapeutic approach with multifaceted applications.

Tau- and α-synuclein-targeted gold nanoparticles: applications, opportunities, and future outlooks in the diagnosis and therapy of neurodegenerative diseases

The use of nanomaterials in medicine offers multiple opportunities to address neurodegenerative disorders such as Alzheimer's and Parkinson's disease. These diseases are a significant burden for society and the health system, affecting millions of people worldwide without sensitive and selective diagnostic methodologies or effective treatments to stop their progression. In this sense, the use of gold nanoparticles is a promising tool due to their unique properties at the nanometric level. They can be functionalized with specific molecules to selectively target pathological proteins such as Tau and α-synuclein for Alzheimer's and Parkinson's disease, respectively. Additionally, these proteins are used as diagnostic biomarkers, wherein gold nanoparticles play a key role in enhancing their signal, even at the low concentrations present in biological samples such as blood or cerebrospinal fluid, thus enabling an early and accurate diagnosis. On the other hand, gold nanoparticles act as drug delivery platforms, bringing therapeutic agents directly into the brain, improving treatment efficiency and precision, and reducing side effects in healthy tissues. However, despite the exciting potential of gold nanoparticles, it is crucial to address the challenges and issues associated with their use in the medical field before they can be widely applied in clinical settings. It is critical to ensure the safety and biocompatibility of these nanomaterials in the context of the central nervous system. Therefore, rigorous preclinical and clinical studies are needed to assess the efficacy and feasibility of these strategies in patients. Since there is scarce and sometimes contradictory literature about their use in this context, the main aim of this review is to discuss and analyze the current state-of-the-art of gold nanoparticles in relation to delivery, diagnosis, and therapy for Alzheimer's and Parkinson's disease, as well as recent research about their use in preclinical, clinical, and emerging research areas.

SLAM (CD150) receptor homologous peptides block the peste des petits ruminants virus entry into B95a cells

The fusion of haemagglutinin-neuraminidase (HN) protein of peste des petits ruminant (PPR) virus with signaling lymphocyte activation molecules (SLAM) host cell receptor consequences the virus entry and multiplication inside the host cell. The use of synthetic SLAM homologous peptides (i.e., molecular decoy for HN protein of PPR virus) may check PPR infection at the preliminary stage. Hence, the predicted SLAM homologous peptides using bioinformatics tools were synthesized by solid phase chemistry with standard Merrifield's 9-fluorenylmethoxycarbonyl (Fmoc) chemistry and were purified by reverse phase high performance liquid chromatography. The secondary structures of synthesized peptides were elucidated by circular dichroism spectroscopy. The in vitro interactions of these peptides were studied through indirect Enzyme Linked Immuno Sorbent Assay (ELISA) and visual surface plasmon UV-visible spectroscopy. The SLAM homologous peptides were able to interact with the peste des petits ruminant virus (PPRV) with varying binding efficiency. The interaction of SLAM homologous peptide with the PPR virus was ascertained by the change in the plasmon color from red wine to purple during visual detection and also by bathochromic shift in absorbance spectra under UV-visible spectrophotometry. The cytotoxic and anti-PPRV effect of these peptides were also evaluated in B95a cell line using PPR virus (Sungri/96). The cytotoxic concentration 50 (CC50 ) value of each peptide was greater than 1000 μg mL-1 . The anti-PPRV efficiency of SLAM-22 was relatively high among SLAM homologous peptides, SLAM-22 at 25 μg mL-1 concentration showed a reduction of more than log10 3 virus titer by priming of B95a cell line while the use of SLAM-15 and Muco-17 at the same concentration dropped virus titer from log10 4.8 to log10 2.5 and log10 3.1 respectively. The concentration of SLAM homologous peptide (25 μg mL-1 ) to exert its anti-PPRV effect was much less than its CC50 level (>1000 μg mL-1 ). Therefore, the synthetic SLAM homologous peptides may prove to be better agents to target PPRV.

Differential Detection of Amyloid Aggregates in Old Animals Using Gold Nanorods by Computerized Tomography: A Pharmacokinetic and Bioaccumulation Study

Introduction

The development of new materials and tools for radiology is key to the implementation of this diagnostic technique in clinics. In this work, we evaluated the differential accumulation of peptide-functionalized GNRs in a transgenic animal model (APPswe/PSENd1E9) of Alzheimer's disease (AD) by computed tomography (CT) and measured the pharmacokinetic parameters and bioaccumulation of the nanosystem.

Methods

The GNRs were functionalized with two peptides, Ang2 and D1, which conferred on them the properties of crossing the blood-brain barrier and binding to amyloid aggregates, respectively, thus making them a diagnostic tool with great potential for AD. The nanosystem was administered intravenously in APPswe/PSEN1dE9 model mice of 4-, 8- and 18-months of age, and the accumulation of gold nanoparticles was observed by computed tomography (CT). The gold accumulation and biodistribution were determined by atomic absorption.

Results

Our findings indicated that 18-month-old animals treated with our nanosystem (GNR-D1/Ang2) displayed noticeable differences in CT signals compared to those treated with a control nanosystem (GNR-Ang2). However, no such distinctions were observed in younger animals. This suggests that our nanosystem holds the potential to effectively detect AD pathology.

Discussion

These results support the future development of gold nanoparticle-based technology as a more effective and accessible alternative for the diagnosis of AD and represent a significant advance in the development of gold nanoparticle applications in disease diagnosis.

Recent trends of bioconjugated nanomedicines through nose-to-brain delivery for neurological disorders

The global burden of neurological disorders has been increasing day by day which calls for immediate attention to the solutions. Novel drug delivery systems are one of the alternatives that we count on to counteract these disorders. As the blood-brain barrier creates a significant hindrance to the delivery of drugs across the endothelium lining of the brain, nose-to-brain delivery has been the favorite option to administer such drugs. In recent times, bioconjugation has been viewed as a rapidly growing area in the field of pharmaceuticals. The pharmaceutical industry and academic research are investing significantly in bioconjugated structures as an attractive and advantageous potential aid to nanoparticulate delivery systems, with all of its flexible benefits in terms of tailor grafting and custom design as well as overcoming the majority of their drawbacks. This review discusses drug delivery via the intranasal route and gives insight into bioconjugation systems for drug molecules, their chemistry, and benefits over other systems. Conjugation of drugs/macromolecules with peptides, carbohydrates, ligands, and nucleic acids has also been discussed in detail. The figure represents few types of novel drug delivery systems and molecules that have been attempted by researchers for nose-to-brain delivery through nasal (mucosal) route for the effective management of epilepsy, Alzheimer's disease, brain cancer, and other brain disorders.

Nanomedicine in the Face of Parkinson's Disease: From Drug Delivery Systems to Nanozymes

The complexity and overall burden of Parkinson's disease (PD) require new pharmacological approaches to counteract the symptomatology while reducing the progressive neurodegeneration of affected dopaminergic neurons. Since the pathophysiological signature of PD is characterized by the loss of physiological levels of dopamine (DA) and the misfolding and aggregation of the alpha-synuclein (α-syn) protein, new proposals seek to restore the lost DA and inhibit the progressive damage derived from pathological α-syn and its impact in terms of oxidative stress. In this line, nanomedicine (the medical application of nanotechnology) has achieved significant advances in the development of nanocarriers capable of transporting and delivering basal state DA in a controlled manner in the tissues of interest, as well as highly selective catalytic nanostructures with enzyme-like properties for the elimination of reactive oxygen species (responsible for oxidative stress) and the proteolysis of misfolded proteins. Although some of these proposals remain in their early stages, the deepening of our knowledge concerning the pathological processes of PD and the advances in nanomedicine could endow for the development of potential treatments for this still incurable condition. Therefore, in this paper, we offer: (i) a brief summary of the most recent findings concerning the physiology of motor regulation and (ii) the molecular neuropathological processes associated with PD, together with (iii) a recapitulation of the current progress in controlled DA release by nanocarriers and (iv) the design of nanozymes, catalytic nanostructures with oxidoreductase-, chaperon, and protease-like properties. Finally, we conclude by describing the prospects and knowledge gaps to overcome and consider as research into nanotherapies for PD continues, especially when clinical translations take place.

Recombinant Protein Micelles to Block Transduction by SARS-CoV-2 Pseudovirus

The continuing emergence of variants of the SARS-CoV-2 virus requires the development of modular molecular therapies. Here, we engineered a recombinant amphiphilic protein, oleosin, to spontaneously self-assemble into multivalent micellar nanostructures which can block the Spike S1 protein of SARS-CoV-2 pseudoviruses (PVs). Short recombinant proteins like oleosin can be formulated more easily than antibodies and can be functionalized with precision through genetic engineering. We cloned S1-binding mini-protein genes called LCBx, previously designed by David Baker's laboratory (UW Seattle), to the N-terminus of oleosin, expressing Oleo-LCBx proteins in E. coli. These proteins largely formed 10-100 nm micelles as verified by dynamic light scattering. Two proteins, Oleo-LCB1 and Oleo-LCB3, were seen to completely and irreversibly block transduction by both wild-type and delta variant PVs into 293T-hsACE2 cells at 10 μM. Presented in multivalent micelles, these proteins reduced transduction by PVs down to a functional protein concentration of 5 nM. Additionally, Oleo-LCB1 micelles outperformed corresponding synthetic LCB1 mini-proteins in reducing transduction by PVs. Tunable aqueous solubility of recombinant oleosin allowed incorporation of peptides/mini-proteins at high concentrations within micelles, thus enhancing drug loading. To validate the potential multifunctionality of the micelles, we showed that certain combinations of Oleo-LCB1 and Oleo-LCB3 performed much better than the individual proteins at the same concentration. These micelles, which we showed to be non-toxic to human cells, are thus a promising step toward the design of modular, multifunctional therapeutics that could bind to and inactivate multiple receptors and proteins necessary for the infection of the SARS-CoV-2 virus.

Crossing the Blood-Brain Barrier: Advances in Nanoparticle Technology for Drug Delivery in Neuro-Oncology

The blood-brain barrier (BBB) constitutes a microvascular network responsible for excluding most drugs from the brain. Treatment of brain tumors is limited by the impermeability of the BBB and, consequently, survival outcomes for malignant brain tumors remain poor. Nanoparticles (NPs) represent a potential solution to improve drug transport to brain tumors, given their small size and capacity to target tumor cells. Here, we review the unique physical and chemical properties of NPs that aid in BBB transport and discuss mechanisms of NP transport across the BBB, including paracellular transport, carrier-mediated transport, and adsorptive- and receptor-mediated transcytosis. The major types of NPs investigated for treatment of brain tumors are detailed, including polymeric NPs, liposomes, solid lipid NPs, dendrimers, metals, quantum dots, and nanogels. In addition to their role in drug delivery, NPs can be used as imaging contrast agents and can be conjugated with imaging probes to assist in visualizing tumors, demarcating lesion boundaries and margins, and monitoring drug delivery and treatment response. Multifunctional NPs can be designed that are capable of targeting tumors for both imaging and therapeutic purposes. Finally, limitations of NPs for brain tumor treatment are discussed.

Nanocarriers for Delivery of Oligonucleotides to the CNS

Nanoparticles with oligonucleotides bound to the outside or incorporated into the matrix can be used for gene editing or to modulate gene expression in the CNS. These nanocarriers are usually optimised for transfection of neurons or glia. They can also facilitate transcytosis across the brain endothelium to circumvent the blood-brain barrier. This review examines the different formulations of nanocarriers and their oligonucleotide cargoes, in relation to their ability to enter the brain and modulate gene expression or disease. The size of the nanocarrier is critical in determining the rate of clearance from the plasma as well as the intracellular routes of endothelial transcytosis. The surface charge is important in determining how it interacts with the endothelium and the target cell. The structure of the oligonucleotide affects its stability and rate of degradation, while the chemical formulation of the nanocarrier primarily controls the location and rate of cargo release. Due to the major anatomical differences between humans and animal models of disease, successful gene therapy with oligonucleotides in humans has required intrathecal injection. In animal models, some progress has been made with intraventricular or intravenous injection of oligonucleotides on nanocarriers. However, getting significant amounts of nanocarriers across the blood-brain barrier in humans will likely require targeting endothelial solute carriers or vesicular transport systems.

Cyclodextrin-Modified Nanomaterials for Drug Delivery: Classification and Advances in Controlled Release and Bioavailability

In drug delivery, one widely used way of overcoming the biopharmaceutical problems present in several active pharmaceutical ingredients, such as poor aqueous solubility, early instability, and low bioavailability, is the formation of inclusion compounds with cyclodextrins (CD). In recent years, the use of CD derivatives in combination with nanomaterials has shown to be a promising strategy for formulating new, optimized systems. The goals of this review are to give in-depth knowledge and critical appraisal of the main CD-modified or CD-based nanomaterials for drug delivery, such as lipid-based nanocarriers, natural and synthetic polymeric nanocarriers, nanosponges, graphene derivatives, mesoporous silica nanoparticles, plasmonic and magnetic nanoparticles, quantum dots and other miscellaneous systems such as nanovalves, metal-organic frameworks, Janus nanoparticles, and nanofibers. Special attention is given to nanosystems that achieve controlled drug release and increase their bioavailability during in vivo studies.

Chemical Enhancement Effect of Icotinib-Au Complex Studied by Combined Density Functional Theory and Surface-Enhanced Raman Scattering

Icotinib is an epidermal growth factor receptor tyrosine kinase inhibitor used in the treatment of non-small cell lung cancer. The charge transfer effect between gold nanoparticles (AuNPs) and icotinib molecules can be used as a model to study the adsorption mechanism between molecules and metal. The adsorption of icotinib on the AuNP surface was confirmed by UV-vis and transmission electron microscopy (TEM) experiments. To explain the nature of chemisorption between icotinib and AuNPs from a theoretical perspective, the molecular correlation properties of the complex model of icotinib-Au₆ were studied by the density functional theory method. By studying the molecular electrostatic potential of an icotinib molecule, four potential binding sites of the icotinib molecule were predicted. The calculation results of binding energy showed that the complex formed by chemisorption of icotinib through acetylene group and Au₆ was the most stable one. The molecular frontier orbitals of icotinib and icotinib-Au₆ confirmed that the charge transfer effect occurred on the acetylene group, benzene ring, and quinazoline ring of the icotinib molecule. The Herzberg-Teller surface selection rule was used to explain selective enhancement in the theoretically calculated Raman spectra. By comparing the spectra of theory and experiment, the cause of spectral peak shift and broadening that appeared in the surface-enhanced Raman scattering spectrum compared with the normal Raman spectrum was explained as well. This work would contribute to the development and application of the icotinib-Au drug carrier system.

Intranasal Delivery of Temozolomide-Conjugated Gold Nanoparticles Functionalized with Anti-EphA3 for Glioblastoma Targeting

Glioblastoma multiforme (GBM) is a highly lethal and aggressive tumor of the brain that carries a poor prognosis. Temozolomide (TMZ) has been widely used as a first-line treatment for GBM. However, poor brain targeting, side effects, and drug resistance limit its application for the treatment of GBM. We designed a Temozolomide-conjugated gold nanoparticle functionalized with an antibody against the ephrin type-A receptor 3 (anti-EphA3-TMZ@GNPs) for targeted GBM therapy via intranasal administration. The system can bypass the blood-brain barrier and target active glioma cells to improve the glioma targeting of TMZ and enhance the treatment efficacy, while reducing the peripheral toxicity and drug resistance. The prepared anti-EphA3-TMZ@GNPs were 46.12 ± 2.0 nm and suitable for intranasal administration, which demonstrated high safety to the nasal mucosa in a toxicity assay. In vitro studies showed that anti-EphA3-TMZ@GNPs exhibited significantly enhanced cellular uptake and toxicity, and a higher cell apoptosis ratio has been seen compared with that of TMZ (54.9 and 14.1%, respectively) toward glioma cells (C6). The results from experiments on TMZ-resistant glioma cells (T98G) demonstrated that the IC₅₀ of anti-EphA3-TMZ@GNPs (64.06 ± 0.16 μM) was 18.5-fold lower than that of TMZ. In addition, Western blot analysis also revealed that anti-EphA3-TMZ@GNPs effectively down-modulated expression of O⁶-methylguanine-DNA methyltransferase and increased chemosensitivity of T98G to TMZ. The antiglioma efficacy in vivo was investigated in orthotopic glioma-bearing rats, and the results demonstrated that the anti-EphA3-TMZ@GNPs prolonged the median survival time to 42 days and increased tumor-cell apoptosis dramatically compared with TMZ. In conclusion, anti-EphA3-TMZ@GNPs could serve as an intranasal drug delivery system for efficacious treatment of GBM.

Microporous silica membranes promote plasmonic nanoparticle stability for SERS detection of uranyl

Silica membrane stabilized gold coated silver (Ag@Au) (i.e., internally etched silica coated Ag@Au (IE Ag@Au@SiO2)) nanoparticles promote surface-enhanced Raman scattering (SERS) activity and detection of uranium(vi) oxide (uranyl) under harsh solution phase conditions including at pH 3-7, with ionic strengths up to 150 mM, and temperatures up to 37 °C for at least 10 hours. These materials overcome traditional solution-phase plasmonic nanomaterial limitations including signal variability and/or degradation arising from nanoparticle aggregation, dissolution, and/or surface chemistry changes. Quantitative uranyl detection occurs via coordination to 3-mercaptopropionate (MPA), a result confirmed through changes in correlated SERS intensities for uranyl and COOH/COO- vibrational modes. Quantification is demonstrated down to 110 nM, a concentration below toxic levels. As pH varies from 3 to 7, the plasmonic properties of the nanoparticles are unchanged, and the uranyl signal depends on both the protonation state of MPA as well as uranyl solubility. High ionic strengths (up to 150 mM) and incubation at 37 °C for at least 10 hours do not impact the SERS activity of uranyl even though slight silica dissolution is observed during thermal treatment. All in all, microporous silica membranes effectively protect the nanoparticles against variations in solution conditions thus illustrating robust tunability for uranyl detection using SERS.

Improving Cell Penetration of Gold Nanorods by Using an Amphipathic Arginine Rich Peptide

Introduction

Gold nanorods are highly reactive, have a large surface-to-volume ratio, and can be functionalized with biomolecules. Gold nanorods can absorb infrared electromagnetic radiation, which is subsequently dispersed as local heat. Gold nanoparticles can be used as powerful tools for the diagnosis and therapy of different diseases. To improve the biological barrier permeation of nanoparticles with low cytotoxicity, in this study, we conjugated gold nanorods with cell-penetrating peptides (oligoarginines) and with the amphipathic peptide CLPFFD.

Methods

We studied the interaction of the functionalized gold nanorods with biological membrane models (liposomes) by dynamic light scattering, transmission electron microscopy and the Langmuir balance. Furthermore, we evaluated the effects on cell viability and permeability with an MTS assay and TEM.

Results and Discussion

The interaction study by DLS, the Langmuir balance and cryo-TEM support that GNR-Arg₇CLPFFD enhances the interactions between GNRs and biological membranes. In addition, cells treated with GNR-Arg₇CLPFFD internalized 80% more nanoparticles than cells treated with GNR alone and did not induce cell damage.

Conclusion

Our results indicate that incorporation of an amphipathic sequence into oligoarginines for the functionalization of gold nanorods enhances biological membrane nanoparticle interactions and nanoparticle cell permeability with respect to nanorods functionalized with oligoarginine. Overall, functionalized gold nanorods with amphipathic arginine rich peptides might be candidates for improving drug delivery by facilitating biological barrier permeation.

Intranasal Delivery of Immunotherapeutic Nanoformulations for Treatment of Glioma Through in situ Activation of Immune Response

PURPOSE

Some chemotherapeutics have been shown to induce both the release of damage-associated molecular patterns (DAMPs) and the production of type I interferon (IFN-I), leading to immunogenic cell death (ICD). However, the standard chemotherapy drug for glioma, temozolomide (TMZ), cannot induce ICD as it cannot activate IFN-I signaling. Moreover, inefficient delivery of immunostimulants across the blood-brain barrier (BBB) is the main obstacle to overcome in order to induce local immune responses in the brain.

METHODS

A new oligonucleotide nanoformulation (Au@PP)/poly(I:C)) was constructed by coating gold nanoparticles (AuNPs) with methoxypolyethylene glycol (mPEG)-detachable (d)-polyethyleneimine (PEI) (Au@PP) followed by inducing the formation of electrostatic interactions with polyinosinic-polycytidylic acid (poly(I:C)). Intracranial GL261 tumor-bearing C57BL/6 mice were used to explore the therapeutic outcomes of Au@PP/poly(I:C) plus TMZ in vivo. The anti-tumor immune response in the brain induced by this treatment was analyzed by RNA sequencing and immunohistochemical analyses.

RESULTS

Au@PP/poly(I:C) induced IFN-I production after endocytosis into glioma cells in vitro. Additionally, Au@PP/poly(I:C) was efficiently accumulated in the glioma tissue after intranasal administration, which allowed the nanoformulation to enter the brain while bypassing the BBB. Furthermore, Au@PP/poly(I:C) plus TMZ significantly improved the overall survival of the tumor-bearing mice compared with group TMZ only. RNA sequencing and immunohistochemical analyses revealed efficient immune response activation and T lymphocyte infiltration in the Au@PP/poly(I:C) plus TMZ group.

CONCLUSION

This study demonstrates that intranasal administration of Au@PP/poly(I:C) combined with TMZ induces ICD, thereby stimulating an in situ immune response to inhibit glioma growth.

Capping gold nanoparticles with albumin to improve their biomedical properties

Nanotechnology is an emerging field which has created great opportunities either through the creation of new materials or by improving the properties of existing ones. Nanoscale materials with a wide range of applications in areas ranging from engineering to biomedicine have been produced. Gold nanoparticles (AuNPs) have emerged as a therapeutic agent, and are useful for imaging, drug delivery, and photodynamic and photothermal therapy. AuNPs have the advantage of ease of functionalization with therapeutic agents through covalent and ionic binding. Combining AuNPs and other materials can result in nanoplatforms, which can be useful for biomedical applications. Biomaterials such as biomolecules, polymers and proteins can improve the therapeutic properties of nanoparticles, such as their biocompatibility, biodistribution, stability and half-life. Serum albumin is a versatile, non-toxic, stable, and biodegradable protein, in which structural domains and functional groups allow the binding and capping of inorganic nanoparticles. AuNPs coated with albumin have improved properties such as greater compatibility, bioavailability, longer circulation times, lower toxicity, and selective bioaccumulation. In the current article, we review the features of albumin, as well as its interaction with AuNPs, focusing on its biomedical applications.

In vitro and in vivo evaluation of a single chain antibody fragment generated in planta with potent rabies neutralisation activity

Rabies causes more than 60,000 human deaths annually in areas where the virus is endemic. Importantly, rabies is one of the few pathogens for which there is no treatment following the onset of clinical disease with the outcome of infection being death in almost 100% of cases. Whilst vaccination, and the combination of vaccine and rabies immunoglobulin treatment for post-exposure administration are available, no tools have been identified that can reduce or prevent rabies virus replication once clinical disease has initiated. The search for effective antiviral molecules to treat those that have already developed clinical disease associated with rabies virus infection is considered one of the most important goals in rabies research. The current study assesses a single chain antibody molecule (ScFv) based on a monoclonal antibody that potently neutralises rabies in vitro as a potential therapeutic candidate. The recombinant ScFv was generated in Nicotiana benthamiana by transient expression, and was chemically conjugated (ScFv/RVG) to a 29 amino acid peptide, specific for nicotinic acetylcholine receptor (nAchR) binding in the CNS. This conjugated molecule was able to bind nAchR in vitro and enter neuronal cells more efficiently than ScFv. The ability of the ScFv/RVG to neutralise virus in vivo was assessed using a staggered administration where the molecule was inoculated either four hours before, two days after or four days after infection. The ScFv/RVG conjugate was evaluated in direct comparison with HRIG and a potential antiviral molecule, Favipiravir (also known as T-705) to indicate whether there was greater bioavailability of the ScFv in the brains of treated mice. The study indicated that the approach taken with the ScFv/RVG conjugate may have utility in the design and implementation of novel tools targetting rabies virus infection in the brain.

Nanoparticle technology and stem cell therapy team up against neurodegenerative disorders

The convergence of nanoparticles and stem cell therapy holds great promise for the study, diagnosis, and treatment of neurodegenerative disorders. Researchers aim to harness the power of nanoparticles to regulate cellular microenvironment, improve the efficiency of cell and drug delivery to the brain, and enhance the survival of stem cell transplants. Understanding the various properties of different nanoparticles is key to applying them to clinical therapies; the many distinct types of nanoparticles offer unique capacities for medical imaging, diagnosis, and treatment of neurodegeneration disorders. In this review we introduce the biology of Alzheimer's, Parkinson's Disease, and amyotrophic lateral sclerosis, and discuss the potentials and shortcomings of metal, silica, lipid-based, polymeric, and hydrogel nanoparticles for diagnosis and treatment of neurodegenerative disorders. We then provide an overview of current strategies in stem cell therapies and how they can be combined with nanotechnology to improve clinical outcomes.

Elucidating the Inability of Functionalized Nanoparticles to Cross the Blood-Brain Barrier and Target Specific Cells in Vivo

The adsorption of serum proteins on the surface of nanoparticles (NPs) delivered into a biological environment has been known to alter NP surface properties and consequently their targeting efficiency. In this paper, we use random copolymer (p(HEMA- ran-GMA))-based NPs synthesized using 2-hydroxyethyl methacrylate (HEMA) and glycidyl methacrylate (GMA). We show that serum proteins bind to the NP and that functionalization with antibodies and peptides designed to facilitate NP passage across the blood-brain barrier (BBB) to bind specific cell types is ineffective. In particular, we use systematic in vitro and in vivo analyses to demonstrate that p(HEMA- ran-GMA) NPs functionalized with HIV-1 trans-activating transcriptor peptide (known to cross the BBB) and α neural/glial antigen 2 (NG2) (known for targeting oligodendrocyte precursor cells (OPCs)), individually and in combination, do not specifically target OPCs and are unable to cross the BBB, likely due to the serum protein binding to the NPs.

Intracisternal delivery of PEG-coated gold nanoparticles results in high brain penetrance and long-lasting stability

Background

The increasing use of gold nanoparticles (AuNPs) in the field of neuroscience instilled hope for their rapid translation to the clinical practice. AuNPs can be engineered to carry therapeutics or diagnostics in the diseased brain, possibly providing greater cell specificity and low toxicity. Although there is a general enthusiasm for these tools, we are in early stages of their development. Overall, their brain penetrance, stability and cell specificity are critical issues that must be addressed to drive AuNPs to the clinic.

Results

We studied the kinetic, distribution and stability of PEG-coated AuNPs in mice receiving a single injection into the cisterna magna of the 4th ventricle. AuNPs were conjugated with the fluorescent tag Cy5.5 (Cy5.5-AuNPs) to track their in vivo distribution. Fluorescence levels from such particles were detected in mice for weeks. In situ analysis of brains by immunofluorescence and electron microscopy revealed that Cy5.5-AuNPs penetrated the brain parenchyma, spreading in the CNS parenchyma beneath the 4th ventricle. Cy5.5-AuNPs were preferentially found in neurons, although a subset of resting microglia also entrapped these particles.

Conclusions

Our results suggest that the ICM route for delivering gold particles allows the targeting of neurons. This approach might be pursued to carry therapeutics or diagnostics inside a diseased brain with a surgical procedure that is largely used in gene therapy approaches. Furthermore, this approach could be used for radiotherapy, enhancing the agent’s efficacy to kill brain cancer cells.

Electronic supplementary material

The online version of this article (10.1186/s12951-019-0481-3) contains supplementary material, which is available to authorized users.

High-Contrast Imaging of Nanodiamonds in Cells by Energy Filtered and Correlative Light-Electron Microscopy: Toward a Quantitative Nanoparticle-Cell Analysis

Fluorescent nanodiamonds (fNDs) represent an emerging class of nanomaterials offering great opportunities for ultrahigh resolution imaging, sensing and drug delivery applications. Their biocompatibility, exceptional chemical and consistent photostability renders them particularly attractive for correlative light-electron microscopy studies providing unique insights into nanoparticle-cell interactions. Herein, we demonstrate a stringent procedure to image and quantify fNDs with a high contrast down to the single particle level in cells. Individual fNDs were directly visualized by energy-filtered transmission electron microscopy, that is, inside newly forming, early endosomal vesicles during their cellular uptake processes as well as inside cellular organelles such as a mitochondrion. Furthermore, we demonstrate the unequivocal identification, localization, and quantification of individual fNDs in larger fND clusters inside intracellular vesicles. Our studies are of great relevance to obtain quantitative information on nanoparticle trafficking and their various interactions with cells, membranes, and organelles, which will be crucial to design-improved sensors, imaging probes, and nanotherapeutics based on quantitative data.

Doxorubicin and indocyanine green loaded superparamagnetic iron oxide nanoparticles with PEGylated phospholipid coating for magnetic resonance with fluorescence imaging and chemotherapy of glioma

Background

Glioma represents the most common malignant brain tumor. Outcomes of surgical resection are often unsatisfactory due to low sensitivity or resolution of imaging methods. Moreover, the use of traditional chemotherapeutics, such as doxorubicin (DOX), is limited due to their low blood-brain barrier (BBB) permeability. Recently, the development of nanotechnology could overcome these obstacles.

Materials and methods

Hydrophobic superparamagnetic iron oxide nanoparticles (SPIO NPs) were prepared with the use of thermal decomposition method. They were coated with 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG 2000) and DOX using a thin-film hydration method followed by loading of indocyanine green (ICG) into the phospholipid layers. Details regarding the characteristics of NPs were determined. The in vitro biocompatibility and antitumor efficacy were established with the use of MTT assay. In vivo fluorescence and magnetic resonance (MR) imaging were used to evaluate BBB penetration and accumulation of NPs at the tumor site. Antitumor efficacy was evaluated using measures of tumor size, median survival times, body weights, and H&E staining.

Results

The multifunctional NPs generated had an average diameter of 22.9 nm, a zeta potential of -38.19 mV, and were capable of providing a sustained release of DOX. In vitro experiments demonstrated that the SPIO@DSPE-PEG/DOX/ICG NPs effectively enhanced cellular uptake of DOX as compared with that of free DOX. In vivo fluorescence and MR imaging revealed that the NPs not only effectively crossed the BBB but selectively accumulated at the tumor site. Meanwhile, among all groups studied, C6 glioma-bearing rats treated with the NPs exhibited the maximal degree of therapeutic efficacy, including smallest tumor volume, lowest body weight loss, and longest survival times, with no obvious side effects.

Conclusion

These results suggest that the SPIO@DSPE-PEG/DOX/ICG NPs can not only function as a nanoprobe for MR and fluorescence bimodal imaging, but also as a vehicle to deliver chemotherapeutic drugs to the tumor site, to achieve the theranostic treatment of glioma.

Gold nanorods/siRNA complex administration for knockdown of PARP-1: a potential treatment for perinatal asphyxia

Background

Perinatal asphyxia interferes with neonatal development, resulting in long-term deficits associated with systemic and neurological diseases. Despite the important role of poly (ADP-ribose) polymerase 1 (PARP-1) in the regulation of gene expression and DNA repair, overactivation of PARP-1 in asphyxia-exposed animals worsens the ATP-dependent energetic crisis. Inhibition of PARP-1 offers a therapeutic strategy for diminishing the effects of perinatal asphyxia.

Methods

We designed a nanosystem that incorporates a specific siRNA for PARP-1 knockdown. The siRNA was complexed with gold nanorods (AuNR) conjugated to the peptide CLPFFD for brain targeting.

Results

The siRNA was efficiently delivered into PC12 cells, resulting in gene silencing. The complex was administered intraperitoneally in vivo to asphyxia-exposed rat pups, and the ability of the AuNR-CLPFFD/siRNA complex to reach the brain was demonstrated.

Conclusion

The combination of a nanosystem for delivery and a specific siRNA for gene silencing resulted in effective inhibition of PARP-1 in vivo.

The Delivery Challenge in Neurodegenerative Disorders: The Nanoparticles Role in Alzheimer's Disease Therapeutics and Diagnostics

Alzheimer’s disease (AD) is one of the main causes of disability and dependency among elderly people. AD is a neurodegenerative disorder characterized by a progressive and irreversible cognitive impairment, whose etiology is unclear because of the complex molecular mechanisms involved in its pathophysiology. A global view of the AD pathophysiology is described in order to understand the need for an effective treatment and why nanoparticles (NPs) could be an important weapon against neurodegenerative diseases by solving the general problem of poor delivery into the central nervous system (CNS) for many drugs. Drug delivery into the CNS is one of the most challenging objectives in pharmaceutical design, due to the limited access to the CNS imposed by the blood-brain barrier (BBB). The purpose of this review is to present a comprehensive overview of the use of NPs as delivery systems for therapeutic and diagnostic purposes in models of AD.

Functionalization of stable fluorescent nanodiamonds towards reliable detection of biomarkers for Alzheimer's disease

Background

Stable and non-toxic fluorescent markers are gaining attention in molecular diagnostics as powerful tools for enabling long and reliable biological studies. Such markers should not only have a long half-life under several assay conditions showing no photo bleaching or blinking but also, they must allow for their conjugation or functionalization as a crucial step for numerous applications such as cellular tracking, biomarker detection and drug delivery.

Results

We report the functionalization of stable fluorescent markers based on nanodiamonds (NDs) with a bifunctional peptide. This peptide is made of a cell penetrating peptide and a six amino acids long β-sheet breaker peptide that is able to recognize amyloid β (Aβ) aggregates, a biomarker for the Alzheimer disease. Our results indicate that functionalized NDs (fNDs) are not cytotoxic and can be internalized by the cells. The fNDs allow ultrasensitive detection (at picomolar concentrations of NDs) of in vitro amyloid fibrils and amyloid aggregates in AD mice brains.

Conclusions

The fluorescence of functionalized NDs is more stable than that of fluorescent markers commonly used to stain Aβ aggregates such as Thioflavin T. These results pave the way for performing ultrasensitive and reliable detection of Aβ aggregates involved in the pathogenesis of the Alzheimer disease.

Electronic supplementary material

The online version of this article (10.1186/s12951-018-0385-7) contains supplementary material, which is available to authorized users.

Evaluating the antimicrobial, apoptotic, and cancer cell gene delivery properties of protein-capped gold nanoparticles synthesized from the edible mycorrhizal fungus Tricholoma crassum

Biosynthesis of gold nanoparticles of distinct geometric shapes with highly functional protein coats without additional capping steps is rarely reported. This study describes green synthesis of protein-coated gold nanoparticles for the first time from the edible, mycorrhizal fungus Tricholoma crassum (Berk.) Sacc. The nanoparticles were of the size range 5-25 nm and of different shapes. Spectroscopic analysis showed red shift of the absorption maxima with longer reaction period during production and blue shift with increase in pH. These were characterized with spectroscopy, SEM, TEM, AFM, XRD, and DLS. The particle size could be altered by changing synthesis parameters. These had potent antimicrobial activity against bacteria, fungi, and multi-drug-resistant pathogenic bacteria. These also had inhibitory effect on the growth kinetics of bacteria and germination of fungal spores. These showed apoptotic properties on eukaryotic cells when tested with comet assays. Moreover, the particles are capped with a natural 40 kDa protein which was utilized as attachment sites for genes to be delivered into sarcoma cancer cells. The present work also attempted at optimizing safe dosage of these nanoparticles using hemolysis assays, for application in therapy. Large-scale production of the nanoparticles in fermentors and other possible applications of the particles have been discussed.

Peptide Mediated Brain Delivery of Nano- and Submicroparticles: A Synergistic Approach

The brain is a complex, regulated organ with a highly controlled access mechanism: The Blood-Brain Barrier (BBB). The selectivity of this barrier is a double-edged sword, being both its greatest strength and weakness. This weakness is evident when trying to target therapeutics against diseases within the brain. Diseases such as metastatic brain cancer have extremely poor prognosis due to the poor permeability of many therapeutics across the BBB. Peptides can be designed to target BBB receptors and gain access to the brain by transcytosis. These peptides (known as BBB-shuttles) can carry compounds, usually excluded from the brain, across the BBB. BBB-shuttles are limited by poor loading of therapeutics and degradation of the peptide and cargo. Likewise, nano- submicro- and microparticles can be fine-tuned to limit their degradation and with high loading of therapeutics. However, most nano- and microparticles' core materials completely lack efficient targeting, with a few selected materials able to cross the BBB passively. Combining the selectivity of peptides with the high loading potential of nano-, microparticles offers an exciting strategy to develop novel, targeted therapeutics towards many brain disorders and diseases. Nevertheless, at present the field is diverse, in both scope and nomenclature, often with competing or contradictory names. In this review, we will try to address some of these issues and evaluate the current state of peptide mediated nano,-microparticle transport to the brain, analyzing delivery vehicle type and peptide design, the two key components that must act synergistically for optimal therapeutic impact.

Immobilization of Neurotrophin Peptides on Gold Nanoparticles by Direct and Lipid-Mediated Interaction: A New Multipotential Therapeutic Nanoplatform for CNS Disorders

Neurotrophins are essential proteins for the development and maintenance of neural functions as well as promising drugs in neurodegenerative disorders. Current limits in their effective clinical applications can be overwhelmed by the combined use of peptidomimetic and nanomedicine approaches. Indeed, neurotrophin-mimicking peptides may allow minimizing the adverse side effects of the whole protein drug. Moreover, the immobilization of such peptides on nanomaterials may offer additional advantages, including protection against degradation, enhanced permeability of barrier membranes, and intrinsic therapeutic properties of the nanoparticles (e.g., antiangiogenic and plasmonic features of gold nanoparticles (AuNPs)). In the present article, we scrutinize the functionalization of spherical AuNPs of diameter 12 nm by peptides because of the N-terminal domains of the nerve growth factor (NGF) and the brain-derived neurotrophic factor (BDNF), NGF1-14 and BDNF1-12, respectively. The hybrid gold-peptide nanobiointerface was investigated, both in the direct physisorption and in the lipid-bilayer-mediated adsorption processes, by a multitechnique study that included UV-vis and X-ray photoelectron spectroscopies, dynamic light scattering, zeta-potential analyses, and atomic force microscopy. Both peptide- and lipid-dependent features were identified, to have a modulation in the peptide coverage of nanoparticles as well as in the cellular uptake of NGF and BDNF peptides, as investigated by confocal microscopy. The promising potentials of the neurotrophins to cross the blood-brain barrier were demonstrated.

Biological mechanisms of gold nanoparticle radiosensitization

There has been growing interest in the use of nanomaterials for a range of biomedical applications over the last number of years. In particular, gold nanoparticles (GNPs) possess a number of unique properties that make them ideal candidates as radiosensitizers on the basis of their strong photoelectric absorption coefficient and ease of synthesis. However, despite promising preclinical evidence in vitro supported by a limited amount of in vivo experiments, along with advances in mechanistic understanding, GNPs have not yet translated into the clinic. This may be due to disparity between predicted levels of radiosensitization based on physical action, observed biological response and an incomplete mechanistic understanding, alongside current experimental limitations. This paper provides a review of the current state of the field, highlighting the potential underlying biological mechanisms in GNP radiosensitization and examining the barriers to clinical translation.

In Vitro Effects of Hollow Gold Nanoshells on Human Aortic Endothelial Cells

Gold nanoparticles are emerging as promising biomedical tools due to their unique nanoscale characteristics. Our purpose was to synthesize a hollow-shaped gold nanoparticle and to investigate its effect on human aortic endothelial cells (HAECs) in vitro. Hollow gold nanoshells with average 35-nm diameters and 10-nm shell thickness were obtained by galvanic replacement using quasi-spherical nanosilver as sacrifice-template. Our results showed that hollow gold nanoshells in the culture medium could be internalized into the cytoplasm of HAECs. No cytotoxicity effect of hollow gold nanoshells on HAECs was observed within the test concentrations (0-0.8 μg/mL) and test exposure period (0-72 h) by tetrazolium dye assay. Meanwhile, the release of cell injury biomarker, lactate dehydrogenase, was not significantly higher than that from control cells (without hollow gold nanoshells). The concentrations of vasodilators, nitric oxide, and prostacyclin I-2 were not changed, but the vasoconstrictor endothelin-1 was decreased by hollow gold nanoshells treatment in HAECs. HAECs exposed to hollow gold nanoshells resulted in suppressing expressions of genes involved in apoptosis and activating expressions of genes of adhesion molecules. Moreover, we demonstrated by in vitro endothelial tube formation that hollow gold nanoshells (0.8 μg/mL) could not inhibit angiogenesis by the HAECs. Altogether, these results indicate that the structure and major function of HAECs would not be disrupted by hollow gold nanoshell treatment.

Recent trends on hydrogel based drug delivery systems for infectious diseases

Since centuries, the rapid spread and cure of infectious diseases have been a major concern to the progress and survival of humans. These diseases are a global burden and the prominent cause for worldwide deaths and disabilities. Nanomedicine has emerged as the most excellent tool to eradicate and halt their spread. Various nanoformulations (NFs) using advanced nanotechnology are in demand. Recently, hydrogel and nanogel based drug delivery devices have posed new prospects to simulate the natural intelligence of various biological systems. Owing to their unique porous interpenetrating network design, hydrophobic drug incorporation and stimulus sensitivity hydrogels owe excellent potential as targeted drug delivery systems. The present review is an attempt to highlight the recent trends of hydrogel based drug delivery systems for the delivery of therapeutic agents and diagnostics for major infectious diseases including acquired immune deficiency syndrome (AIDS), malaria, tuberculosis, influenza and ebola. Future prospects and challenges are also described.

Development of bimetallic (Zn@Au) nanoparticles as potential PET-imageable radiosensitizers

PURPOSE

Gold nanoparticles (GNPs) are being investigated actively for various applications in cancer diagnosis and therapy. As an effort to improve the imaging of GNPs in vivo, the authors developed bimetallic hybrid Zn@Au NPs with zinc cores and gold shells, aiming to render them in vivo visibility through positron emission tomography (PET) after the proton activation of the zinc core as well as capability to induce radiosensitization through the secondary electrons produced from the gold shell when irradiated by various radiation sources.

METHODS

Nearly spherical zinc NPs (∼5-nm diameter) were synthesized and then coated with a ∼4.25-nm gold layer to make Zn@Au NPs (∼13.5-nm total diameter). 28.6 mg of these Zn@Au NPs was deposited (∼100 μm thick) on a thin cellulose target and placed in an aluminum target holder and subsequently irradiated with 14.15-MeV protons from a GE PETtrace cyclotron with 5-μA current for 5 min. After irradiation, the cellulose matrix with the NPs was placed in a dose calibrator to assess the induced radioactivity. The same procedure was repeated with 8-MeV protons. Gamma ray spectroscopy using an high-purity germanium detector was conducted on a very small fraction (<1 mg) of the irradiated NPs for each proton energy. In addition to experimental measurements, Monte Carlo simulations were also performed with radioactive Zn@Au NPs and solid GNPs of the same size irradiated with 160-MeV protons and 250-kVp x-rays.

RESULTS

The authors measured 168 μCi of activity 32 min after the end of bombardment for the 14.15-MeV proton energy sample using the (66)Ga setting on a dose calibrator; activity decreased to 2 μCi over a 24-h period. For the 8-MeV proton energy sample, PET imaging was additionally performed for 5 min after a 12-h delay. A 12-h gamma ray spectrum showed strong peaks at 511 keV (2.05 × 10(6) counts) with several other peaks of smaller magnitude for each proton energy sample. PET imaging showed strong PET signals from mostly decaying (66)Ga. The Monte Carlo results showed that radioactive Zn@Au NPs and solid GNPs provided similar characteristics in terms of their secondary electron spectra when irradiated.

CONCLUSIONS

The Zn@Au NPs developed in this investigation have the potential to be used as PET-imageable radiosensitizers for radiotherapy applications as well as PET tracers for molecular imaging applications.

Kinetics of functionalised carbon nanotube distribution in mouse brain after systemic injection: Spatial to ultra-structural analyses

Earlier studies proved the success of using chemically functionalised multi-walled carbon nanotubes (f-MWNTs) as nanocarriers to the brain. Little insight into the kinetics of brain distribution of f-MWNTs in vivo has been reported. This study employed a wide range of qualitative and quantitative techniques with the aim of shedding the light on f-MWNT's brain distribution following intravenous injection. γ-Scintigraphy quantified the uptake of studied radiolabelled f-MWNT in the whole brain parenchyma and capillaries while 3D-single photon emission computed tomography/computed tomography imaging and autoradiography illustrated spatial distribution within various brain regions. Raman and multiphoton luminescence together with transmission electron microscopy confirmed the presence of intact f-MWNT in mouse brain, in a label-free manner. The results evidenced the presence of f-MWNT in mice brain parenchyma, in addition to brain endothelium. Such information on the rate and extent of regional and cellular brain distribution is needed before further implementation into neurological therapeutics can be made.

MiniAp-4: A Venom-Inspired Peptidomimetic for Brain Delivery

Drug delivery across the blood–brain barrier (BBB) is a formidable challenge for therapies targeting the central nervous system. Although BBB shuttle peptides enhance transport into the brain non‐invasively, their application is partly limited by lability to proteases. The present study proposes the use of cyclic peptides derived from venoms as an affordable way to circumvent this drawback. Apamin, a neurotoxin from bee venom, was minimized by reducing its complexity, toxicity, and immunogenicity, while preserving brain targeting, active transport, and protease resistance. Among the analogues designed, the monocyclic lactam‐bridged peptidomimetic MiniAp‐4 was the most permeable. This molecule is capable of translocating proteins and nanoparticles in a human‐cell‐based BBB model. Furthermore, MiniAp‐4 can efficiently deliver a cargo across the BBB into the brain parenchyma of mice.