Ring-opening metathesis polymerization-based synthesis of polymeric nanoparticles for enhanced tumor imaging in vivo: Synergistic effect of folate-receptor targeting and PEGylation

Osmium and OsO x nanoparticles: an overview of syntheses and applications

Precious metal nanoparticles are key for a range of applications ranging from catalysis and sensing to medicine. While gold (Au), silver (Ag), platinum (Pt), palladium (Pd) or ruthenium (Ru) nanoparticles have been widely studied, other precious metals are less investigated. Osmium (Os) is one of the least studied of the precious metals. However, Os nanoparticles are interesting materials since they present unique features compared to other precious metals and Os nanomaterials have been reported to be useful for a range of applications, catalysis or sensing for instance. With the increasing availability of advanced characterization techniques, investigating the properties of relatively small Os nanoparticles and clusters has become easier and it can be expected that our knowledge on Os nanomaterials will increase in the coming years. This review aims to give an overview on Os and Os oxide materials syntheses and applications.

A clinical trial of super-stable homogeneous lipiodol-nanoICG formulation-guided precise fluorescent laparoscopic hepatocellular carcinoma resection

Background

Applying traditional fluorescence navigation technologies in hepatocellular carcinoma is severely restricted by high false-positive rates, variable tumor differentiation, and unstable fluorescence performance.

Results

In this study, a green, economical and safe nanomedicine formulation technology was developed to construct carrier-free indocyanine green nanoparticles (nanoICG) with a small uniform size and better fluorescent properties without any molecular structure changes compared to the ICG molecule. Subsequently, nanoICG dispersed into lipiodol via a super-stable homogeneous intermixed formulation technology (SHIFT&nanoICG) for transhepatic arterial embolization combined with fluorescent laparoscopic hepatectomy to eliminate the existing shortcomings. A 52-year-old liver cancer patient was recruited for the clinical trial of SHIFT&nanoICG. We demonstrate that SHIFT&nanoICG could accurately identify and mark the lesion with excellent stability, embolism, optical imaging performance, and higher tumor-to-normal tissue ratio, especially in the detection of the microsatellite lesions (0.4 × 0.3 cm), which could not be detected by preoperative imaging, to realize a complete resection of hepatocellular carcinoma under fluorescence laparoscopy in a shorter period (within 2 h) and with less intraoperative blood loss (50 mL).

Conclusions

This simple and effective strategy integrates the diagnosis and treatment of hepatocellular carcinoma, and thus, it has great potential in various clinical applications.

Supplementary information

The online version contains supplementary material available at 10.1186/s12951-022-01467-w.

Nanohybrids as Protein-Polymer Conjugate Multimodal Therapeutics

Protein therapeutic formulations are being widely explored as multifunctional nanotherapeutics. Challenges in ensuring susceptibility and efficacy of nanoformulation still prevail owing to various interactions with biological fluids before reaching the target site. Smart polymers with the capability of masking drugs, ease of chemical modification, and multi-stimuli responsiveness can assist controlled delivery. An active moiety like therapeutic protein has started to be known as an important biological formulation with a diverse medicinal prospect. The delivery of proteins and peptides with high target specificity has however been tedious, due to their tendency to aggregate formation in different environmental conditions. Proteins due to high chemical reactivity and poor bioavailability are being researched widely in the field of nanomedicine. Clinically, multiple nano-based formulations have been explored for delivering protein with different carrier systems. A biocompatible and non-toxic polymer-based delivery system serves to tailor the polymer or drug better. Polymers not only aid delivery to the target site but are also responsible for proper stearic orientation of proteins thus protecting them from internal hindrances. Polymers have been shown to conjugate with proteins through covalent linkage rendering stability and enhancing therapeutic efficacy prominently when dealing with the systemic route. Here, we present the recent developments in polymer-protein/drug-linked systems. We aim to address questions by assessing the properties of the conjugate system and optimized delivery approaches. Since thorough characterization is the key aspect for technology to enter into the market, correlating laboratory research with commercially available formulations will also be presented in this review. By examining characteristics including morphology, surface properties, and functionalization, we will expand different hybrid applications from a biomaterial stance applied in in vivo complex biological conditions. Further, we explore understanding related to design criteria and strategies for polymer-protein smart nanomedicines with their potential prophylactic theranostic applications. Overall, we intend to highlight protein-drug delivery through multifunctional smart polymers.

Supramolecular behaviour and fluorescence of rhodamine-functionalised ROMP polymers

A ROMP platform leading to rhodamine B containing amphiphilic block copolymers, which self-assemble into micelles which are able to sequester molecular dyes and interact with them by energy transfer. The polymer micelles do not interact with DNA.

Grubbs' and Schrock's Catalysts, Ring Opening Metathesis Polymerization and Molecular Brushes-Synthesis, Characterization, Properties and Applications

In this review, molecular brushes and other macromolecular architectures bearing a bottlebrush segment where the main chain is synthesized by ring opening metathesis polymerization (ROMP) mediated by Mo or Ru metal complexes are considered. A brief review of metathesis and ROMP is presented in order to understand the problems and the solutions provided through the years. The synthetic strategies towards bottlebrush copolymers are demonstrated and each one discussed separately. The initiators/catalysts for the synthesis of the backbone with ROMP are discussed. Syntheses of molecular brushes are presented. The most interesting properties of the bottlebrushes are detailed. Finally, the applications studied by different groups are presented.

Biodistribution of arctigenin-loaded nanoparticles designed for multimodal imaging

BACKGROUND

Tracking targets of natural products is one of the most challenging issues in fields ranging from pharmacognosy to biomedicine. It is widely recognized that the biocompatible nanoparticle (NP) could function as a "key" that opens the target "lock".

RESULTS

We report a functionalized poly-lysine NP technique that can monitor the target protein of arctigenin (ATG) in vivo non-invasively. The NPs were synthesized, and their morphologies and surface chemical properties were characterized by transmission electron microscopy (TEM), laser particle size analysis and atomic force microscopy (AFM). In addition, we studied the localization of ATG at the level of the cell and the whole animal (zebrafish and mice). We demonstrated that fluorescent NPs could be ideal carriers in the development of a feasible method for target identification. The distributions of the target proteins were found to be consistent with the pharmacological action of ATG at the cellular and whole-organism levels.

CONCLUSIONS

The results indicated that functionalized poly-lysine NPs could be valuable in the multimodal imaging of arctigenin.

Polymer Structure and Conformation Alter the Antigenicity of Virus-like Particle-Polymer Conjugates

Covalent conjugation of water-soluble polymers to proteins is critical for evading immune surveillance in the field of biopharmaceuticals. The most common and long-standing polymer modification is the attachment of methoxypoly(ethylene glycol) (mPEG), termed PEGylation, which has led to several clinically approved pharmaceuticals. Recent data indicate that brush-type polymers significantly enhance in vitro and in vivo properties. Herein, the polymer conformation of poly(ethylene glycol) is detailed and compared with those of water-soluble polyacrylate and polynorbornene (PNB) when attached to icosahedral virus-like particles. Small-angle neutron scattering reveals vastly different polymer conformations of the multivalent conjugates. Immune recognition of conjugated particles was evaluated versus PEGylated particles, and PNB conjugation demonstrated the most effective shielding from antibody recognition.

Preparation of multilocation reduction-sensitive core crosslinked folate-PEG-coated micelles for rapid release of doxorubicin and tariquidar to overcome drug resistance

Herein, we prepared folate-targeting core crosslinked polymeric micelles (CCL/FA) containing multiple disulfide bonds located at the interface and core of the micelles to co-deliver doxorubicin (DOX) and the P-glycoprotein (P-gp) inhibitor tariquidar (TQR) for reversing drug resistance. The stability and redox-responsive behavior of the CCL/FA micelles was evaluated through the changes in morphology, molecular weight and hydrodynamic size. On the one hand, the micelles possessed good stability, which led to the suppression of drug release from the CCL micelles in the physiological environment. On the other hand, under reductive conditions, the CCL micelles collapsed rapidly and accelerated drug release markedly. In vitro cytotoxicity measurements, combined with confocal laser scanning microscopy (CLSM) and flow cytometry, confirmed that the dual-drug-loaded micelles exhibited obviously higher cytotoxicity to MCF-7/ADR-resistant cells than free DOX · HCl, single-drug loaded CCL micelles and nontargeted CCL micelles. The results imply that co-delivering DOX and TQR by CCL/FA micelles may be a promising way of overcoming multidrug resistance in tumor treatments.

Fluorescent Polymer Nanoparticles Based on Dyes: Seeking Brighter Tools for Bioimaging

Speed, resolution and sensitivity of today's fluorescence bioimaging can be drastically improved by fluorescent nanoparticles (NPs) that are many-fold brighter than organic dyes and fluorescent proteins. While the field is currently dominated by inorganic NPs, notably quantum dots (QDs), fluorescent polymer NPs encapsulating large quantities of dyes (dye-loaded NPs) have emerged recently as an attractive alternative. These new nanomaterials, inspired from the fields of polymeric drug delivery vehicles and advanced fluorophores, can combine superior brightness with biodegradability and low toxicity. Here, we describe the strategies for synthesis of dye-loaded polymer NPs by emulsion polymerization and assembly of pre-formed polymers. Superior brightness requires strong dye loading without aggregation-caused quenching (ACQ). Only recently several strategies of dye design were proposed to overcome ACQ in polymer NPs: aggregation induced emission (AIE), dye modification with bulky side groups and use of bulky hydrophobic counterions. The resulting NPs now surpass the brightness of QDs by ≈10-fold for a comparable size, and have started reaching the level of the brightest conjugated polymer NPs. Other properties, notably photostability, color, blinking, as well as particle size and surface chemistry are also systematically analyzed. Finally, major and emerging applications of dye-loaded NPs for in vitro and in vivo imaging are reviewed.

Histone Deacetylase Inhibitors Delivery using Nanoparticles with Intrinsic Passive Tumor Targeting Properties for Tumor Therapy

Fast clearance, metabolism and systemic toxicity are major limits for the clinical use of anti-cancer drugs. Histone deacetylase inhibitors (HDACi) present these defects despite displaying promising anti-tumor properties on tumor cells in vitro and in in vivo model of cancers. Specific delivery of anti-cancer drugs into the tumor should improve their clinical benefit by limiting systemic toxicity and by increasing the anti-tumor effect. In this work, we describe a simple and flexible polymeric nanoparticle platform highly targeting the tumor in vivo and triggering impressive tumor weight reduction when functionalized with HDACi. Our nanoparticles were produced by Ring-Opening Metathesis Polymerization of azido-polyethylene oxide-norbornene macromonomers and functionalized using click chemistry. Using an orthotopic model of peritoneal invasive cancer, a highly selective accumulation of the particles in the tumor was obtained. A combination of epigenetic drugs involving a pH-responsive histone deacetylase inhibitor (HDACi) polymer conjugated to these particles gave 80% reduction of tumor weight without toxicity whereas the free HDACi has no effect. Our work demonstrates that the use of a nanovector with theranostic properties leads to an optimized delivery of potent HDACi in tumor and then, to an improvement of their anti-tumor properties in vivo.

A targeted agent with intercalation structure for cancer near-infrared imaging and photothermal therapy

A new targeted photothermal agent is synthesized by co-intercalation of indocyanine green (ICG) and folic acid (FA) into the layered double hydroxide (LDH), which can be potentially used in cancer NIR imaging and photothermal therapy (PTT) field.

NANOTECHNOLOGY - NEW TRENDS IN THE TREATMENT OF BRAIN TUMOURS

High grade gliomas are some of the deadliest human tumours. Conventional treatments such as surgery, radiotherapy and chemotherapy have only a limited effect. Nowadays, resection is the common treatment of choice and although new approaches, such as perioperative magnetic resonance imaging or fluorescent microscopy have been developed, the survival rate of diagnosed patients is still very low. The inefficacy of conventional methods has led to the development of new strategies and the significant progress of nanotechnology in recent years. These platforms can be used either as novel imaging tools or to improve anticancer drug delivery into tumours while minimizing its distribution and toxicity in healthy tissues. Amongst the new nanotechnology platforms used for delivery into the brain tissue are: polymeric nanoparticles, liposomes, dendrimers, nanoshells, carbon nanotubes, superparamagnetic nanoparticles and nucleic acid based nanoparticles (DNA, RNA interference [RNAi] and antisense oligonucleotides [ASO]). These nanoparticles have been applied in the delivery of small molecular weight drugs as well as macromolecules - proteins, peptides and genes. The unique properties of these nanoparticles, such as surface charge, particle size, composition and ability to modify their surface with tissue recognition ligands and antibodies, improve their biodistribution and pharmacokinetics. All of the above mentioned characteristics make of nanoplatforms a very suitable tool for its use in targeted, personalized medicine, where they could possibly carry large doses of therapeutic agents specifically into malignant cells while avoiding healthy cells. This review poses new possibilities in the large field of nanotechnology with special interest in the treatment of high grade brain tumours.

Soft fluorescent nanomaterials for biological and biomedical imaging

Soft fluorescent nanomaterials have attracted recent attention as imaging agents for biological applications, because they provide the advantages of good biocompatibility, high brightness, and easy biofunctionalization. Here, we provide a survey of recent developments in fluorescent soft nano-sized biological imaging agents. Various soft fluorescent nanoparticles (NPs) (including dye-doped polymer NPs, semiconducting polymer NPs, small-molecule organic NPs, nanogels, micelles, vesicles, and biomaterial-based NPs) are summarized from the perspectives of preparation methods, structure, optical properties, and surface functionalization. Based on both optical and functional properties of the nano-sized imaging agents, their applications are then reviewed in terms of in vitro imaging, in vivo imaging, and cellular-process imaging, by means of specific or nonspecific targeting.

Indocyanine green-loaded nanoparticles for image-guided tumor surgery

Detecting positive tumor margins and local malignant masses during surgery is critical for long-term patient survival. The use of image-guided surgery for tumor removal, particularly with near-infrared fluorescent imaging, is a potential method to facilitate removing all neoplastic tissue at the surgical site. In this study we demonstrate a series of hyaluronic acid (HLA)-derived nanoparticles that entrap the near-infrared dye indocyanine green, termed NanoICG, for improved delivery of the dye to tumors. Self-assembly of the nanoparticles was driven by conjugation of one of three hydrophobic moieties: aminopropyl-1-pyrenebutanamide (PBA), aminopropyl-5β-cholanamide (5βCA), or octadecylamine (ODA). Nanoparticle self-assembly, dye loading, and optical properties were characterized. NanoICG exhibited quenched fluorescence that could be activated by disassembly in a mixed solvent. NanoICG was found to be nontoxic at physiologically relevant concentrations and exposure was not found to inhibit cell growth. Using an MDA-MB-231 tumor xenograft model in mice, strong fluorescence enhancement in tumors was observed with NanoICG using a fluorescence image-guided surgery system and a whole-animal imaging system. Tumor contrast with NanoICG was significantly higher than with ICG alone.

Sonication-induced formation of size-controlled self-assemblies of amphiphilic Janus-type polymers as optical tumor-imaging agents

In this study, amphiphilic Janus-type polymers were synthesized via ring-opening metathesis polymerization (ROMP), multiple vicinal diol formation, and grafting of poly(ethylene glycol) monomethyl ether (mPEG). These amphiphilic polymers formed self-assemblies, which were a mixture of micelles and multimicellar aggregates, in water. By choosing suitable Janus-type polymers and irradiating an aqueous solution of polymers using a sonicator, either small micelles or large multimicellar aggregates were obtained selectively. Hydrophobic substituents controlled the aggregation-disaggregation behavior, leading to the formation of metastable self-assemblies by sonication. The formation of self-assemblies with a uniform size was affected by ultrasonic frequency, rather than power. In vivo optical tumor imaging revealed that the large-size multimicellar aggregates persisting for a long time in blood circulation slowly accumulated in tumor tissues. In contrast, the tumor site was rapidly, clearly visualized using the small-size micelles.

Advances in imaging probes and optical microendoscopic imaging techniques for early in vivo cancer assessment

A new chapter in the history of medical diagnosis happened when the first X-ray technology was invented in the late 1800s. Since then, many non-invasive and minimally invasive imaging techniques have been invented for clinical diagnosis to research in cellular biology, drug discovery, and disease monitoring. These imaging modalities have leveraged the benefits of significant advances in computer, electronics, and information technology and, more recently, targeted molecular imaging. The development of targeted contrast agents such as fluorescent and nanoparticle probes coupled with optical imaging techniques has made it possible to selectively view specific biological events and processes in both in vivo and ex vivo systems with great sensitivity and selectivity. Thus, the combination of targeted molecular imaging probes and optical imaging techniques have become a mainstay in modern medicinal and biological research. Many promising results have demonstrated great potentials to translate to clinical applications. In this review, we describe a discussion of employing imaging probes and optical microendoscopic imaging techniques for cancer diagnosis.

Nanoparticles produced by ring-opening metathesis polymerization using norbornenyl-poly(ethylene oxide) as a ligand-free generic platform for highly selective in vivo tumor targeting

We described a norbornenyl-poly(ethylene oxide) nanoparticles ligand-free generic platform, made fluorescent with straightforward preparation by ring-opening metathesis polymerization (ROMP). Our method allowed to easily obtain a drug delivery system (DDS) with facilitated functionalization by means of azide-alkyne click chemistry and with a high selectivity for the tumor in vivo, while cellular internalization is obtained without cell targeting strategy. We demonstrated that our nanoparticles are internalized by endocytosis and colocalized with acidic intracellular compartments in two models of aggressive tumoral cell lines with low prognostic and limited therapeutic treatments. Our nanoparticles could be of real interest to limit the toxicity and to increase the clinical benefit of drugs suffering rapid clearance and side effects and an alternative for cancers with poorly efficient therapeutic solutions by associating the drug delivery in the tumor tissue with an acid-sensitive release system.

Exogenous near-infrared fluorophores and their applications in cancer diagnosis: biological and clinical perspectives

INTRODUCTION

Near-infrared fluorescent (NIRF) imaging is a rapidly growing research field which has the potential to be an important imaging modality in cancer diagnosis. Various exogenous NIR fluorophores have been developed for the technique, including small molecule fluorophores and nanoparticles. NIRF imaging has been used in animal models for the detection of cancer overthe last twenty years and has in recent years been used in human clinical trials.

AREAS COVERED

This article describes the types and characteristics of exogenous fluorophores available for in vivo fluorescent cancer imaging. The article also discusses the progression of NIRF cancer imaging over recent years and its future challenges, from both a biological and clinical perspective. in The review also looks at its application for lymph node mapping, tumor targeting and characterization, and tumor margin definition for surgical guidance.

EXPERT OPINION

NIRF imaging is not in routine clinical cancer practice; yet, the authors predict that techniques using NIR fluorophores for tumor margin definition and lymph node mapping will enter clinical practice in the near future. The authors also anticipate that NIRF imaging research will lead to the development of flurophores with 'high brightness' that will overcome the limited penetration of this modality and be better suited for non invasive tumor targeting.

Surface modification of iron oxide nanoparticles by biocompatible polymers for tissue imaging and targeting

Superparamagnetic iron oxide nanoparticles (SPIONs) are excellent MR contrast agents when coated with biocompatible polymers such as hydrophilic synthetic polymers, proteins, polysaccharides, and lipids, which improve their stability and biocompatibility and reduce their aggregation. Various biocompatible materials, coated or conjugated with targeting moieties such as galactose, mannose, folic acid, antibodies and RGD, have been applied to SPION surfaces to provide tissue specificity to hepatocytes, macrophages, and tumor regions in order to reduce non-specific uptake and improve biocompatibility. This review discusses the recent progress in the development of biocompatible and hydrophilic polymers for improving stability of SPIONs and describes the carbohydrates based biocompatible materials that are providing SPIONs with cell/tissue specificity as ligands.

Fluorescent nanoprobes dedicated to in vivo imaging: from preclinical validations to clinical translation

With the fast development, in the last ten years, of a large choice of set-ups dedicated to routine in vivo measurements in rodents, fluorescence imaging techniques are becoming essential tools in preclinical studies. Human clinical uses for diagnostic and image-guided surgery are also emerging. In comparison to low-molecular weight organic dyes, the use of fluorescent nanoprobes can improve both the signal sensitivity (better in vivo optical properties) and the fluorescence biodistribution (passive “nano” uptake in tumours for instance). A wide range of fluorescent nanoprobes have been designed and tested in preclinical studies for the last few years. They will be reviewed and discussed considering the obstacles that need to be overcome for their potential everyday use in clinics. The conjugation of fluorescence imaging with the benefits of nanotechnology should open the way to new medical applications in the near future.

Enhanced tumor treatment using biofunctional indocyanine green-containing nanostructure by intratumoral or intravenous injection

Indocyanine green (ICG) is a conventional dye that can be used in clinical near-infrared (NIR) imaging, and it is also an effective light absorber for laser-mediated photothermal therapy. However, applications of ICG were limited due to its fast degradation in aqueous media and quick clearance from the body. Herein, an ICG-containing nanostructure, ICG-PL-PEG, was developed for photothermal therapy, which was self-assembled by ICG and phospholipid-polyethylene glycol (PL-PEG). Our in vitro and in vivo experiments demonstrated that ICG-PL-PEG suspension was more efficient in producing a NIR-dependent temperature increase than ICG alone, due to the increase of ICG monomers from the addition of PL-PEG to match the central wavelength of the 808 nm laser. When conjugated with integrin α(v)β(3) monoclonal antibody (mAb), ICG-PL-PEG could be selectively internalized and retained in target tumor cells. Irradiation of an 808 nm laser after intravenous administration of ICG-PL-PEG-mAb resulted in tumor suppression in mice, while ICG alone had only limited effect. This is the first time an ICG-containing nanostructure has been used through systemic administration to achieve an efficient in vivo photothermal effect for cancer treatment. Therefore, ICG-PL-PEG could be used as a fluorescent marker as well as a light-absorber for imaging-guided photothermal therapy. All the components of ICG-PL-PEG have been approved for human use. Therefore, this unique ICG-containing nanostructure has great potential in clinical applications.

Influence of side chain length on fluorescence intensity of ROMP-based polymeric nanoparticles and their tumor specificity in in-vivo tumor imaging

In this study, amphiphilic brush-like copolymers conjugated with short alkyl or long polymeric chains of various lengths are synthesized using ring-opening metathesis polymerization (ROMP) of substituted norbornadiene monomers followed by chemical transformations. These amphiphilic copolymers form spherical self-assemblies in aqueous media with diameters of 132-244 nm. The low critical aggregation concentration of these assemblies (2.5 × 10(-3) -1.4 × 10(-5) g/L) indicates that they are quite stable in dilute conditions. An appropriate length of polymer side chain that conjugates the polymer backbone with a hydrophobic ICG (indocyanine green) moiety enhanced the fluorescence intensities of these self-assemblies in aqueous solution as well as in tumor-bearing mice. A longer side chain conjugated with tumor targeting agents could significantly affect the tumor specificity of self-assemblies to a greater extent. The self-assemblies bearing hydrophilic tumor targeting agents, such as a glucosamine molecule and a cyclic RGD (arginine-glycine-asparatic acid) peptide, accumulated in tumor tissues with high selectivity, while those having a hydrophobic targeting agent, such as folate moieties, accumulated in tumor sites with low selectivity. The results demonstrated here unambiguously indicate that the fluorescence intensity and tumor specificity of self-assemblies are strongly affected by the length of side chains that conjugate with dyes and targeting agents.

Integrin-targeting block copolymer probes for two-photon fluorescence bioimaging

Targeted molecular imaging with two-photon fluorescence microscopy (2PFM) is a powerful technique for chemical biology and, potentially, for noninvasive diagnosis and treatment of a number of diseases. The synthesis, photophysical studies, and bioimaging are reported for a versatile norbornene-based block copolymer multifunctional scaffold containing biocompatible (PEG), two-photon fluorescent dyes (fluorenyl) and targeting (cyclic-RGD peptide) moieties. The two bioconjugates, containing two different fluorenyl dyes and cRGDfK covalently attached to the polymer probe, formed a spherical micelle and self-assembled structure in water, for which size was analyzed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). Cell viability and 2PFM imaging of human epithelial U87MG cell lines that overexpress α(v)β(3) integrin was performed via incubation with the new probes, along with negative control studies using MCF-7 breast cancer cells and blocking experiments. 2PFM microscopy confirmed the high selectivity of the biocompatible probe in the integrin-rich area in the U87MF cells while blocking as well as negative control MCF-7 experiments confirmed the integrin-targeting ability of the new probes.