Targeted tumor dual mode CT/MR imaging using multifunctional polyethylenimine-entrapped gold nanoparticles loaded with gadolinium

Radiolabeled multi-layered coated gold nanoparticles as potential biocompatible PET/SPECT tracers

The demand for tailored, disease-adapted, and easily accessible radiopharmaceuticals is one of the most persistent challenges in nuclear imaging precision medicine. The aim of this work was to develop two multimodal radiotracers applicable for both SPECT and PET techniques, which consist of a gold nanoparticle core, a shell involved in radioisotope entrapment, peripherally placed targeting molecules, and biocompatibilizing polymeric sequences. Shell decoration with glucosamine units located in sterically hindered molecular environments is expected to result in nanoparticle accumulation in high-glucose-consuming areas. Gold cores were synthesized using the Turkevich method, followed by citrate substitution with linear PEG α,ω-functionalized with thiol and amine groups. The free amine groups facilitated the binding of branched polyethyleneimine through an epoxy ring-opening reaction by using PEG α,ω-diglycidyl ether as a linker. Afterwards, the glucose-PEG-epoxy prepolymer has been grafted onto the surface of AuPEG-PEI conjugates. Finally, the AuPEG-PEI-GA conjugates were radiolabeled with 99mTc or 68Ga. Instant thin-layer chromatography was used to evaluate the radiolabeling yield. The biocompatibility of non-labeled and 99mTc or 68Ga labeled nanoparticles was assessed on normal fibroblasts. The 99mTc complexes remained stable for over 22 hours, while the 68Ga containing ones revealed a slight decrease in stability after 1 hour.

Gold Polymer Nanomaterials: A Promising Approach for Enhanced Biomolecular Imaging

Gold nanoparticles (AuNPs) possess unique optical properties, making them highly attractive nanomaterials for biomedical research. By exploiting the diverse optical characteristics of various gold nanostructures, significant enhancements can be achieved in biosensing and biomedical imaging fields. The potential of AuNPs can be enhanced by creating hybrid nanocomposites with polymers, which offer supplementary functionalities, responsiveness, and enhanced biocompatibility. Moreover, polymers can modify the surface charges of AuNPs, thereby improving or controlling the efficiency of cellular uptake and the distribution of these nanoparticles within the body. Polymer modification using AuNPs offers a wide array of benefits, including improved sensitivity, specificity, speed, contrast, resolution, and penetration depth. By incorporating AuNPs into the polymer matrix, these enhancements synergistically enhance the overall performance of various applications. This versatile approach opens promising possibilities in fields such as biomedicine, nanotechnology, and sensor development, providing a powerful platform for advanced research and technological innovations. In this review, the recent advancements in polymer-AuNPs synthesis and their applications in bioimaging will be covered. Prospects and challenges associated with polymer-AuNPs-based bioimaging agents in preclinical and clinical investigations will be discussed.

Polyethyleneimine-Based Drug Delivery Systems for Cancer Theranostics

With the development of nanotechnology, various types of polymer-based drug delivery systems have been designed for biomedical applications. Polymer-based drug delivery systems with desirable biocompatibility can be efficiently delivered to tumor sites with passive or targeted effects and combined with other therapeutic and imaging agents for cancer theranostics. As an effective vehicle for drug and gene delivery, polyethyleneimine (PEI) has been extensively studied due to its rich surface amines and excellent water solubility. In this work, we summarize the surface modifications of PEI to enhance biocompatibility and functionalization. Additionally, the synthesis of PEI-based nanoparticles is discussed. We further review the applications of PEI-based drug delivery systems in cancer treatment, cancer imaging, and cancer theranostics. Finally, we thoroughly consider the outlook and challenges relating to PEI-based drug delivery systems.

Silk Fibroin-Induced Gadolinium-Functionalized Gold Nanoparticles for MR/CT Dual-Modal Imaging-Guided Photothermal Therapy

The development of multifunction nanoplatforms integrating accurate diagnosis and efficient therapy is of great significance for the precise treatment of tumors. Gold nanoparticles (AuNPs) possessing hallmark features of computed tomography (CT) imaging and photothermal conversion capability hold great potential in tumor theranostics. In this study, taking the advantages of outstanding biocompatibility, interesting anti-inflammatory and immunomodulatory properties, and abundant amino acid residues of silk fibroin (SF), a multifunctional Gd-hybridized AuNP nanoplatform was constructed using SF as a stabilizer and reductant via a facile one-pot biomimetic method, denoted as Gd:AuNPs@SF. The obtained Gd:AuNPs@SF possessed fascinating biocompatibility and excellent photothermal conversion efficiency. Functionalized with Gd, Gd:AuNPs@SF exhibited super tumor-contrasted imaging performance in magnetic resonance (MR) and CT imaging modalities. Moreover, Gd:AuNPs@SF, with strong NIR absorbance, demonstrated that it could effectively kill tumor cells in vitro, and was also proved to successfully ablate tumor tissues through MR/CT imaging-guided photothermal therapy (PTT) without systemic toxicity in Pan02 xenograft C57BL/6 mouse models. We successfully synthesized Gd:AuNPs@SF for MR/CT dual-mode imaging-guided PTT via a facile one-pot biomimetic method, and this biomimetic strategy can also be used for the construction of other multifunction nanoplatforms, which is promising for precise tumor theranostics.

Multifunctional Gold Nanoparticles in Cancer Diagnosis and Treatment

Cancer is the second leading cause of death in the world, behind only cardiovascular diseases, and is one of the most serious diseases threatening human health nowadays. Cancer patients’ lives are being extended by the use of contemporary medical technologies, such as surgery, radiotherapy, and chemotherapy. However, these treatments are not always effective in extending cancer patients’ lives. Simultaneously, these approaches are often accompanied with a series of negative consequences, such as the occurrence of adverse effects and an increased risk of relapse. As a result, the development of a novel cancer-eradication strategy is still required. The emergence of nanomedicine as a promising technology brings a new avenue for the circumvention of limitations of conventional cancer therapies. Gold nanoparticles (AuNPs), in particular, have garnered extensive attention due to their many specific advantages, including customizable size and shape, multiple and useful physicochemical properties, and ease of functionalization. Based on these characteristics, many therapeutic and diagnostic applications of AuNPs have been exploited, particularly for malignant tumors, such as drug and nucleic acid delivery, photodynamic therapy, photothermal therapy, and X-ray-based computed tomography imaging. To leverage the potential of AuNPs, these applications demand a comprehensive and in-depth overview. As a result, we discussed current achievements in AuNPs in anticancer applications in a more methodical manner in this review. Also addressed in depth are the present status of clinical trials, as well as the difficulties that may be encountered when translating some basic findings into the clinic, in order to serve as a reference for future studies.

Iron oxide nanoparticles as a drug carrier reduce host immunosuppression for enhanced chemotherapy

Chemotherapy is still regarded as the main modality for cancer treatment. However, it often suppresses the host immune system, resulting in limited therapeutic effects. It is desirable to design a novel chemotherapeutic agent to reduce the level of immunosuppression. Herein, we designed bovine serum albumin (BSA)-bioinspired iron oxide nanoparticles (IONPs) as a nanocarrier to load anticancer drug mitoxantrone (MTX) for enhanced chemotherapy of orthotopic breast cancer. The treatment with IONPs@BSA-MTX complexes increased CD3⁺CD4⁺ and CD3⁺CD8⁺ T lymphocytes more than free MTX. The complexes effectively restored the host immune system and exhibited a better anticancer efficacy than free MTX. It was worth noting that the BSA-inspired IONPs were a satisfactory contrast agent for magnetic resonance imaging of tumors and lymph nodes. Our work provides a novel strategy for enhanced chemotherapy with low levels of immunosuppression in the treatment of breast cancer and other cancers.

Click and Bioorthogonal Chemistry: The Future of Active Targeting of Nanoparticles for Nanomedicines?

Over the years, click and bioorthogonal reactions have been the subject of considerable research efforts. These high-performance chemical reactions have been developed to meet requirements not often provided by the chemical reactions commonly used today in the biological environment, such as selectivity, rapid reaction rate, and biocompatibility. Click and bioorthogonal reactions have been attracting increasing attention in the biomedical field for the engineering of nanomedicines. In this review, we study a compilation of articles from 2014 to the present, using the terms "click chemistry and nanoparticles (NPs)" to highlight the application of this type of chemistry for applications involving NPs intended for biomedical applications. This study identifies the main strategies offered by click and bioorthogonal chemistry, with respect to passive and active targeting, for NP functionalization with specific and multiple properties for imaging and cancer therapy. In the final part, a novel and promising approach for "two step" targeting of NPs, called pretargeting (PT), is also discussed; the principle of this strategy as well as all the studies listed from 2014 to the present are presented in more detail.

Recent advances in bionanomaterials for liver cancer diagnosis and treatment

According to the World Health Organization, liver cancer is the fourth leading cause of cancer associated with death worldwide. It demands effective treatment and diagnostic strategies to hinder its recurrence, complexities, aggressive metastasis and late diagnosis. With recent progress in nanotechnology, several nanoparticle-based diagnostic and therapeutic modalities have entered into clinical trials. With further developments in nanoparticle mediated liver cancer diagnosis and treatment, the approach holds promise for improved clinical liver cancer management. In this review, we discuss the key advances in nanoparticles that have potential for liver cancer diagnosis and treatment. We also discuss the potential of nanoparticles to overcome the limitations of existing therapeutic modalities.

Gold nanoparticles meet medical radionuclides

Thanks to their unique optical and physicochemical properties, gold nanoparticles have gained increased interest as radiosensitizing, photothermal therapy and optical imaging agents to enhance the effectiveness of cancer detection and therapy. Furthermore, their ability to carry multiple medically relevant radionuclides broadens their use to nuclear medicine SPECT and PET imaging as well as targeted radionuclide therapy. In this review, we discuss the radiolabeling process of gold nanoparticles and their use in (multimodal) nuclear medicine imaging to better understand their specific distribution, uptake and retention in different in vivo cancer models. In addition, radiolabeled gold nanoparticles enable image-guided therapy is reviewed as well as the enhancement of targeted radionuclide therapy and nanobrachytherapy through an increased dose deposition and radiosensitization, as demonstrated by multiple Monte Carlo studies and experimental in vitro and in vivo studies.

Multifunctional theranostic nanoparticles for biomedical cancer treatments - A comprehensive review

Modern-day search for the novel agents (their preparation and consequent implementation) to effectively treat the cancer is mainly fuelled by the historical failure of the conventional treatment modalities. Apart from that, the complexities such as higher rate of cell mutations, variable tumor microenvironment, patient-specific disparities, and the evolving nature of cancers have made this search much stronger in the latest times. As a result of this, in about two decades, the theranostic nanoparticles (TNPs) - i.e., nanoparticles that integrate therapeutic and diagnostic characteristics - have been developed. The examples for TNPs include mesoporous silica nanoparticles, luminescence nanoparticles, carbon-based nanomaterials, metal nanoparticles, and magnetic nanoparticles. These TNPs have emerged as single and powerful cancer-treating multifunctional nanoplatforms, as they widely provide the necessary functionalities to overcome the previous/conventional limitations including lack of the site-specific delivery of anti-cancer drugs, and real-time continuous monitoring of the target cancer sites while performing therapeutic actions. This has been mainly possible due to the association of the as-developed TNPs with the already-available unique diagnostic (e.g., luminescence, photoacoustic, and magnetic resonance imaging) and therapeutic (e.g., photothermal, photodynamic, hyperthermia therapy) modalities in the biomedical field. In this review, we have discussed in detail about the recent developments on the aforementioned important TNPs without/with targeting ability (i.e., attaching them with ligands or tumor-specific antibodies) and also the strategies that are implemented to increase their tumor accumulation and to enhance their theranostic efficacies for effective biomedical cancer treatments.

Gold nanoparticle-based nanoprobes with enhanced tumor targeting and photothermal/photodynamic response for therapy of osteosarcoma

Plasmonic nanomaterials, especially a wide variety of gold nanoparticles, demonstrate great potential for theranostics of cancer. Herein, a gold nanotriangle with CD133 and hyaluronic acid on its surface loaded with a near-infrared photosensitizer was prepared for enhanced photodynamic/photothermal combined anti-tumor therapy. CD133 and hyaluronic acid provide the nanoprobe with dual tumor targeting, while the hyaluronic acid also protects photosensitive drugs from photodegradation. Thus, the nanoprobe has enhanced photothermal/photodynamic effects. This integrated treatment strategy significantly enhanced photodynamic/photothermal destruction of osteosarcoma cells. In addition, this treatment, induced by mild irradiation with a single wavelength laser, inhibited tumor growth in an osteosarcoma mouse model. These results indicate that this systemic treatment strategy can achieve enhanced anti-tumor therapeutic effects through active tumor targeting and protection of the loaded drugs.

"Stealth" dendrimers with encapsulation of indocyanine green for photothermal and photodynamic therapy of cancer

Poly(amido amine) dendrimers and indocyanine green have inevitable interaction with proteins and cells, which induces biological toxicity and reduces therapeutic efficacy in vivo. To overcome these shortcomings, a new drug delivery system G5MEK7C(n)-ICG with a "stealth" layer was prepared. The surface of G5MEK7C(n)-ICG was modified with double-layer super hydrophilic zwitterionic materials. In the "stealth" double-layer structure, the outer layer was consisted of zwitterionic Glu-Lys-Glu-Lys-Glu-Lys-Cys (EK7) peptide, and the inner layer was composed of amino and carboxyl groups with a ratio of 1:1. DLS results showed that the average hydrodynamic size of G5MEK7C(n)-ICG was about 25-30 nm, and the zeta potential was proven to undergo a slight charge reversal with the increasing pH values of solutions. Furthermore, G5MEK7C(n)-ICG exhibited excellent biocompatibility to red blood cells and proteins resistance. Photothermal and photodynamic experiments demonstrated that G5MEK7C(n)-ICG had a good photothermal conversion effect and generated singlet oxygen (¹O₂) under laser irradiation. The MTT and hemolysis results showed that the toxicity of G5 PAMAM was significantly reduced after modification double-layer structure. Cytotoxicity studies and flow cytometry showed G5MEK7C(70)-ICG under laser irradiation had a good effect on killing A549 cells. More importantly, the tumor inhibition rate of mice treated with G5MEK7C(70)-ICG (under laser irradiation) was 78.2% in vivo, which was higher than that of mice treated with free ICG. Compared with free ICG, G5MEK7C(70)-ICG caused less damage to the liver according to the enzyme activities of alanine aminotransferase (ALT) and aspartate aminotransferase (AST). Therefore, dendrimers modified with a zwitterionic double layer will be a promising candidate as a drug delivery system.

Ultra-small gold nanoparticles self-assembled by gadolinium ions for enhanced photothermal/photodynamic liver cancer therapy

Gold nanomaterials are widely used in biomedical research as drug delivery systems, imaging agents and therapeutic materials owing to their unique physicochemical properties and high biocompatibility. In this study, we prepared ultra-small gold nanoparticles (AuNPs) and induced them with gadolinium ions to form a spherical self-assembly. The nanoparticles were coupled with matrix metalloproteinase-2 (MMP-2) and loaded with the photosensitive drug IR820 for photothermal/photodynamic combination therapy of liver cancer. The formed nanoprobes were metabolised in vivo via degradation under dual-mode real-time imaging because of their acid response degradation characteristics. In addition, the nanoprobe showed excellent tumour-targeting ability due to the presence of surface-modified MMP-2. In vivo treatment experiments revealed that the nanoprobes achieved enhanced photodynamic/photothermal combination therapy under laser irradiation and significantly inhibited tumour growth. Therefore, the nanoprobes have great potential for anti-tumour therapy guided by dual-mode real-time imaging of liver cancer.

Synthesis and Application of Fe3O4@Au Composite Nanoparticles as Magnetic Resonance/Computed Tomography Dual-Modality Contrast Agent

Background:

None of the molecular imaging modalities can produce imaging with both anatomical and functional information. In recent years, to overcome these limitations multimodality molecular imaging or combination of two imaging modalities can provide anatomical and pathological information.

Methods:

Magnetic iron oxide nanoparticles were prepared by co-precipitation method and then were coated with silica according to Stober method. Consequently, silica-coated nanoparticles were amino-functionalized. Finally, gold nanoparticles assembled onto the surfaces of the previous product. Cytotoxicity effects of prepared Fe₃O₄@Au nanoparticles were evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay on human hepatocellular carcinoma cells. Their ability as a dual-mode contrast agent was investigated by magnetic resonance (MR) and computed tomography (CT) imaging.

Results:

Fe₃O₄@Au nanoparticles were spherical undersize of 75 nm. X-ray diffraction analysis confirmed the formation of Fe₃O₄@Au nanoparticles. The magnetometry result confirmed the superparamagnetism property of prepared nanoparticles, and the saturation magnetization (M_s) was found to be 33 emu/g. Fe₃O₄@Au nanoparticles showed good cytocompatibility up to 60 μg/mL. The results showed that the Fe₃O₄@Au nanoparticles have good r₂ relaxivity (135.26 mM⁻¹s⁻¹) and good X-ray attenuation property.

Conclusion:

These findings represent that prepared Fe₃O₄@Au nanoparticles in an easy and relatively low-cost manner have promising potential as a novel contrast agent for dual-modality of MR/CT imaging.

Polymeric Nanoparticles for Drug Delivery: Recent Developments and Future Prospects

The complexity of some diseases—as well as the inherent toxicity of certain drugs—has led to an increasing interest in the development and optimization of drug-delivery systems. Polymeric nanoparticles stand out as a key tool to improve drug bioavailability or specific delivery at the site of action. The versatility of polymers makes them potentially ideal for fulfilling the requirements of each particular drug-delivery system. In this review, a summary of the state-of-the-art panorama of polymeric nanoparticles as drug-delivery systems has been conducted, focusing mainly on those applications in which the corresponding disease involves an important morbidity, a considerable reduction in the life quality of patients—or even a high mortality. A revision of the use of polymeric nanoparticles for ocular drug delivery, for cancer diagnosis and treatment, as well as nutraceutical delivery, was carried out, and a short discussion about future prospects of these systems is included.

Multifunctional Dendrimer-Entrapped Gold Nanoparticles for Labeling and Tracking T Cells Via Dual-Modal Computed Tomography and Fluorescence Imaging

Nanosystems for monitoring and tracking T cells provide an important basis for evaluating the functionality and efficacy of T cell-based immunotherapy. To this end, we designed herein an efficient nanoprobe for T cell monitoring and tracking using poly(amidoamine) (PAMAM) dendrimer-entrapped gold nanoparticles (Au DENPs) conjugated with Fluo-4 for dual-mode computed tomography (CT) and fluorescence imaging. In this study, PAMAM dendrimers of generation 5 (G5) were modified with hydroxyl-terminated polyethylene glycol (PEG) and then used to entrap 2.0 nm Au NPs followed by acetylation of the excess amine groups on the dendrimer surface. Subsequently, the calcium ion probe was covalently attached to the dendrimer nanohybrids through the PEG hydroxyl end groups to gain the functional {(Au⁰)₂₅-G5.NHAc-(PEG)₁₄-(Fluo-4)₂} nanoprobe. This nanoprobe had excellent water solubility, high X-ray attenuation coefficient, and good cytocompatibility in the given concentration range, as well as a high T cell labeling efficiency. Confocal microscopy and flow cytometry results demonstrated that the nanoprobe was able to fluorescently sense activated T cells. Moreover, the nanoprobe was able to realize both CT and fluorescence imaging of subcutaneously injected T cells in vivo. Thus, the developed novel dendrimer-based nanosystem may hold great promise for advancing and improving the clinical application of T cell-based immunotherapy.

Combined Magnetic Resonance Imaging and Photodynamic Therapy Using Polyfunctionalised Nanoparticles Bearing Robust Gadolinium Surface Units

A robust dithiocarbamate tether allows novel gadolinium units based on DOTAGA (q=1) to be attached to the surface of gold nanoparticles (2.6-4.1 nm diameter) along with functional units offering biocompatibility, targeting and photodynamic therapy. A dramatic increase in relaxivity (r₁ ) per Gd unit from 5.01 mm^-1  s^-1 in unbound form to 31.68 mm^-1  s^-1 (10 MHz, 37 °C) is observed when immobilised on the surface due to restricted rotation and enhanced rigidity of the Gd complex on the nanoparticle surface. The single-step synthetic route provides a straightforward and versatile way of preparing multifunctional gold nanoparticles, including examples with conjugated zinc-tetraphenylporphyrin photosensitizers. The lack of toxicity of these materials (MTT assays) is transformed on irradiation of HeLa cells for 30 minutes (PDT), leading to 75 % cell death. In addition to passive targeting, the inclusion of units capable of actively targeting overexpressed folate receptors illustrates the potential of these assemblies as targeted theranostic agents.

Synthesis and Evaluation of ¹⁹⁸Au/PAMAM-MPEG-FA against Cancer Cells

BACKGROUND

There is a significant dearth of clinical biochemistry researches to evaluate the facility of exploitation of folate targeted radioactive gold-labeled anti-cancer drugs against various cancer cell lines.

OBJECTIVE

The aim of this paper was to develop a gold-based compound with an efficient therapeutic potential against breast cancer. To this end, the synthesis of the 198Au/PAMAM-MPEG-FA composite was considered here.

METHODS

The radioactive gold (198Au) nanoparticles were encapsulated into Folic acid (FA)-targeted Polyamidoamine dendrimer (PAMAM) modified with Maleimide-Polyethylene glycol Succinimidyl Carboxymethyl ester (MPEG). After that, anticancer assessments of the prepared 198Au/PAMAM-MPEG-FA hybrid mater against breast cancer were investigated. Further studies were also devised to compare the anticancer capabilities of the 198Au/PAMAM-MPEG-FA composite with the synthesized P-MPEG, 197Au/P-MPEG, 197Au/P-MPEG-FA, 197Au/P-FA and 198Au/P-MPEG-FA conjugates. The prepared drugs were characterized by means of various analytical techniques. The radionuclidic purity of the 198Au/P-MPEG-FA solution was determined using High Purity Germanium (HPGe) spectroscopy and its stability in the presence of human serum was studied. The cell uptake and toxicity of the prepared drugs were evaluated in vitro, and some comparative studies of the toxicity of the drugs were conducted towards the MCF7 (Human breast cancer cell), 4T1 (Mice breast adenocarcinoma cell) and C2C12 (Mice muscle normal cell).

RESULTS

The results showed that cell uptake of 198Au/P-MPEG-FA nanoparticles is high in the 4T1 cell line and the order of uptake is as 4T1> MCF7> C2C12. Moreover, of the tested compounds, 198Au/P-MPEG-FA had the highest toxicity towards the cancerous 4T1 and MCF7 in all concentrations after 24, 48 and 72h (P < 0.001). Furthermore, the cytotoxicity of the drugs was concentration-dependent.

CONCLUSION

On the basis of the present research, 198Au/P-MPEG-FA has been proposed as a good candidate for the induction of cell death in breast cancer, although further experimental and clinical investigations are required.

Gold nanomaterials functionalised with gadolinium chelates and their application in multimodal imaging and therapy

An overview of recent progress in the design of gadolinium-functionalised gold nanoparticles for use in MRI, multimodal imaging and theranostics.

99mTc-Labeled Polyethylenimine-Entrapped Gold Nanoparticles with pH-Responsive Charge Conversion Property for Enhanced Dual Mode SPECT/CT Imaging of Cancer Cells

Development of tumor dual mode contrast agents is still a great challenge due to the relative low accumulation at tumor site, which result in the poor imaging efficiency. In this study, we constructed functional technetium-99m (^99mTc) labeled polyethylenimine (PEI)-entrapped gold nanoparticles (Au PENs) with pH-responsive charge conversion property for enhanced single photon emission computed tomography (SPECT)/computed tomography (CT) dual mode imaging of cancer cells. PEI with amine functional groups (PEI.NH₂) was successively modified with monomethyl ether and carboxyl functionalized polyethylene glycol (mPEG-COOH), maleimide and succinimidyl valerate functionalized PEG (MAL-PEG-SVA), diethylenetriaminepentaacetic dianhydride (DTPA), and fluorescein isothiocyanate (FI), and used to entrapped gold nanoparticles inside, followed by conjugation with the alkoxyphenyl acylsulfonamide (APAS) through the PEG maleimide, acetylation of the PEI leftover surface amines and ^99mTc labeling. The created nanosystem with the mean Au core diameter of 3.3 nm and with a narrow size distribution displays an excellent colloidal stability and desired cytocompatibility in the investigated Au concentration range. Due to the fact that the attached APAS moieties are responsive to pH, the functionalized Au PENs with a neutral surface charge can switch to be positively charged under slightly acidic pH condition, which could improve the cellular uptake by cancer cells. With these properties, the developed functionalized Au PENs could achieve enhanced dual mode SPECT/CT imaging of cancer cells in vitro. The constructed PEI-based nanodevices may be adopted as an excellent dual mode contrast agent for SPECT/CT imaging of cancer cells of different types.

Fluorescein sodium loaded by polyethyleneimine for fundus fluorescein angiography improves adhesion

Aim: To improve the retention of fluorescein sodium (FS) as a kind of clinical contrast agent for fundus fluorescein angiography (FFA). Materials & methods: Polyethyleneimine (PEI) was designed to synthesize PEI–NHAc–FS nanoparticles (NPs), and the formed NPs were characterized by both physicochemical properties and their effects on FFA. Results: Compared with free FS, PEI–NHAc–FS NPs showed similar optical performance, and could obviously reduce cellular adsorption and uptake both in vitro and in vivo, which could promote the metabolism of NPs in ocular blood vessels. Conclusion: PEI–NHAc–FS NPs represent a smart nanosize fluorescence contrast agent, which hold promising potential for clinical FFA diagnosis, therapy and research work.

Polyfunctionalised Nanoparticles Bearing Robust Gadolinium Surface Units for High Relaxivity Performance in MRI

The first example of an octadentate gadolinium unit based on DO3A (hydration number q=1) with a dithiocarbamate tether has been designed and attached to the surface of gold nanoparticles (around 4.4 nm in diameter). In addition to the superior robustness of this attachment, the restricted rotation of the Gd complex on the nanoparticle surface leads to a dramatic increase in relaxivity (r₁ ) from 4.0 mm^-1  s^-1 in unbound form to 34.3 mm^-1  s^-1 (at 10 MHz, 37 °C) and 22±2 mm^-1  s^-1 (at 63.87 MHz, 25 °C) when immobilised on the surface. The one-pot synthetic route provides a straightforward and versatile way of preparing a range of multifunctional gold nanoparticles. The incorporation of additional surface units for biocompatibility (PEG and thioglucose units) and targeting (folic acid) leads to little detrimental effect on the high relaxivity observed for these non-toxic multifunctional materials. In addition to the passive targeting attributed to gold nanoparticles, the inclusion of a unit capable of targeting the folate receptors overexpressed by cancer cells, such as HeLa cells, illustrates the potential of these assemblies.

Zwitterionic Gadolinium(III)-Complexed Dendrimer-Entrapped Gold Nanoparticles for Enhanced Computed Tomography/Magnetic Resonance Imaging of Lung Cancer Metastasis

Design of dual mode or multimode contrast agents or nanoplatforms with antifouling properties is crucial for improved cancer diagnosis since the antifouling materials are able to escape the clearance of the reticuloendothelial system with improved pharmacokinetics. Herein, we present the creation of zwitterionic gadolinium(III) (Gd(III))-complexed dendrimer-entrapped gold nanoparticles (Au DEN) for enhanced dual mode computed tomography (CT)/magnetic resonance (MR) imaging of lung cancer metastasis. In the present work, poly(amidoamine) (PAMAM) dendrimers of generation 5 were partially decorated with carboxybetanie acrylamide (CBAA), 2-methacryloyloxyethyl phosphorylcholine (MPC), and 1,3-propane sultone (1,3-PS), respectively at different degrees, then used to entrap Au NPs within their interiors, and finally acetylated to cover their remaining amine termini. Through protein resistance, macrophage cellular uptake, and pharmacokinetics assays, we show that zwitterionic Au DEN modified with 1,3-PS exhibit the best antifouling property with the longest half-decay time (37.07 h) when compared to the CBAA- and MPC-modified Au DEN. Furthermore, with the optimized zwitterion type, we then prepared zwitterionic Gd(III)-loaded Au DEN modified with arginine-glycine-aspartic acid peptide for targeted dual mode CT/MR imaging of a lung cancer metastasis model. We disclose that the designed multifunctional Au DEN having an Au core size of 2.7 nm and a surface potential of 7.6 ± 0.9 mV display a good X-ray attenuation property, relatively high r₁ relaxivity (13.17 mM s^-1), acceptable cytocompatibility, and targeting specificity to α_vβ₃ integrin-expressing cancer cells and enable effective dual mode CT/MR imaging of a lung cancer metastasis model in vivo. The developed multifunctional zwitterion-functionalized Au DEN may be potentially adopted as an effective nanoprobe for enhanced dual-modal CT/MR imaging of other cancer types.

BSA-bioinspired gold nanorods loaded with immunoadjuvant for the treatment of melanoma by combined photothermal therapy and immunotherapy

The development of therapeutic methods that can effectively delay tumor growth, inhibit tumor metastases, and protect the host from tumor recurrence still faces challenges. Nanoparticle-based combination therapy may provide an effective therapeutic strategy. Herein, we show that bovine serum albumin (BSA)-bioinspired gold nanorods (GNRs) were loaded with an immunoadjuvant for combined photothermal therapy (PTT) and immunotherapy for the treatment of melanoma. In this work, cetyltrimethylammonium bromide (CTAB)-coated GNRs were successively decorated with polyethylene glycol (PEG) and BSA, and loaded with an immunoadjuvant imiquimod (R837). The synthesized mPEG-GNRs@BSA/R837 nanocomplexes under near-infrared (NIR) irradiation could effectively kill tumors and trigger strong immune responses in treating metastatic melanoma in mice. Furthermore, the nanocomplex-based PTT prevented lung metastasis and induced a strong long-term antitumor immunity to protect the treated mice from tumor recurrence. The nanocomplex-based PTT in combination with immunotherapy may be potentially employed as an effective strategy for the treatment of melanoma and other metastatic cancers.

SPECT/CT imaging of chemotherapy-induced tumor apoptosis using 99mTc-labeled dendrimer-entrapped gold nanoparticles

Non-invasive imaging of apoptosis in tumors induced by chemotherapy is of great value in the evaluation of therapeutic efficiency. In this study, we report the synthesis, characterization, and utilization of radionuclide technetium-99m (99mTc)-labeled dendrimer-entrapped gold nanoparticles (Au DENPs) for targeted SPECT/CT imaging of chemotherapy-induced tumor apoptosis. Generation five poly(amidoamine) (PAMAM) dendrimers (G5.NH2) were sequentially conjugated with 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA), polyethylene glycol (PEG) modified duramycin, PEG monomethyl ether, and fluorescein isothiocyanate (FI) to form the multifunctional dendrimers, which were then utilized as templates to entrap gold nanoparticles. Followed by acetylation of the remaining dendrimer surface amines and radiolabeling of 99mTc, the SPECT/CT dual mode nanoprobe of tumor apoptosis was constructed. The developed multifunctional Au DENPs before and after 99mTc radiolabeling were well characterized. The results demonstrate that the multifunctional Au DENPs display favorable colloidal stability under different conditions, own good cytocompatibility in the given concentration range, and can be effectively labeled by 99mTc with high radiochemical stability. Furthermore, the multifunctional nanoprobe enables the targeted SPECT/CT imaging of apoptotic cancer cells in vitro and tumor apoptosis after doxorubicin (DOX) treatment in the established subcutaneous tumor model in vivo. The designed duramycin-functionalized Au DENPs might have the potential to be employed as a nanoplatform for the detection of apoptosis and early tumor response to chemotherapy.

Doxorubicin-Conjugated PAMAM Dendrimers for pH-Responsive Drug Release and Folic Acid-Targeted Cancer Therapy

We present here the development of multifunctional doxorubicin (DOX)-conjugated poly(amidoamine) (PAMAM) dendrimers as a unique platform for pH-responsive drug release and targeted chemotherapy of cancer cells. In this work, we covalently conjugated DOX onto the periphery of partially acetylated and folic acid (FA)-modified generation 5 (G5) PAMAM dendrimers through a pH-sensitive cis-aconityl linkage to form the G5.NHAc-FA-DOX conjugates. The formed dendrimer conjugates were well characterized using different methods. We show that DOX release from the G5.NHAc-FA-DOX conjugates follows an acid-triggered manner with a higher release rate under an acidic pH condition (pH = 5 or 6, close to the acidic pH of tumor microenvironment) than under a physiological pH condition. Both in vitro cytotoxicity evaluation and cell morphological observation demonstrate that the therapeutic activity of dendrimer-DOX conjugates against cancer cells is absolutely related to the DOX drug released. More importantly, the FA conjugation onto the dendrimers allowed a specific targeting to cancer cells overexpressing FA receptors (FAR), and allowed targeted inhibition of cancer cells. The developed G5.NHAc-FA-DOX conjugates may be used as a promising nanodevice for targeted cancer chemotherapy.

Gadolinium-labelled iron/iron oxide core/shell nanoparticles as T 1-T 2 contrast agent for magnetic resonance imaging

Magnetic resonance imaging (MRI) is indispensable and powerful in modern clinical diagnosis and has some advantages such as non-invasiveness and high penetration depth. Furthermore, dual T 1-T 2 MR imaging has attracted crucial interest as it can decrease the risk of pseudo-positive signals in diagnosing lesions. And it's worth nothing that the dual-mode MR imaging displays a vital platform to provide relatively comprehensive diagnosis information and receive accurate results. Herein, we report a dual T 1-T 2 MR imaging contrast agent (CA) grounded on the iron/iron oxide core/shell nanomaterials conjugated with gadolinium chelate. The Gd-labeled Fe@Fe3O4 NPs reveal the feasibility to utilize them to serve as a dual T 1-T 2 MR imaging CA, and the relaxivity results in a 0.5 T MR system showed a longitudinal relaxivity value (r 1) and transverse relaxivity value (r 2) of 7.2 mM-1 s-1 and 109.4 mM-1 s-1, respectively. The MTT results demonstrate the Gd-labeled Fe@Fe3O4 NPs have no obvious cytotoxicity and a good compatibility. The in vitro and in vivo MRI generated a brighter effect and darkening in T 1-weighted MR imaging and T 2-weighted images, respectively. The results clearly indicate that Gd-labeled Fe@Fe3O4 NPs have potential as a magnetic resonance imaging contrast reagent.

Acetylated Polyethylenimine-Entrapped Gold Nanoparticles Enable Negative Computed Tomography Imaging of Orthotopic Hepatic Carcinoma

Developing an effective computed tomography (CT) contrast agent is still a challenging task for precise diagnosis of hepatic carcinoma (HCC). Here, we present the use of acetylated polyethylenimine (PEI)-entrapped gold nanoparticles (Ac-PE-AuNPs) without antifouling modification for negative CT imaging of HCC. PEI was first linked to fluorescein isothiocyanate (FI) and then utilized as a vehicle for the entrapment of AuNPs. The particles were then acetylated to reduce its positive surface potential. The designed Ac-PE-AuNPs were characterized by various techniques. We find that the Ac-PE-AuNPs with a uniform size distribution (mean diameter = 2.3 nm) are colloidally stable and possess low toxicity in the studied range of concentration. Owing to the fact that the particles without additional antifouling modification were mainly gathered in liver, the Ac-PE-AuNPs could greatly improve the CT contrast enhancement of normal liver, whereas poor CT contrast enhancement appeared in liver necrosis region caused by HCC. As a result, HCC could be easily and precisely diagnosed. The designed Ac-PE-AuNPs were demonstrated to have biocompatibility through in vivo biodistribution and histological studies, hence holding an enormous potential to be adopted as an effective negative CT contrast agent for diagnosis of hepatoma carcinoma.