Melanin-gelatin nanoparticles with both EPR effect and renal clearance for PA/MRI dual-modal imaging of tumors

Matrix metalloproteinase-responsive melanin nanoparticles utilize live neutrophils for targeted high-risk plaque detection and atherosclerosis regression

Abrupt rupture of atherosclerotic plaque is the predominant contributor to acute cardiovascular events. It is of clinical importance to effectively identify and inhibit high-risk plaque progression. However, this remains a major challenge due to the inadequate targeting of theranostic agents to atherosclerotic lesions. Herein, we utilize live neutrophils to encapsulate melanin-based theranostics (termed MNPpep-Gd) to enhance their plaque targeting, leveraging the inherent inflammatory tropism of neutrophils in atherosclerosis progression. The MNPpep-Gd are fabricated using the water-insoluble gadolinium-chelated melanin nanoparticle modified with a detachable polyethylene glycol (PEG) segment via a matrix metalloproteinase (MMP)-cleavable peptide linker. Our work demonstrated that overexpressed MMP in high-risk plaques can induce an increase in particle size and prolonged retention time of the MNPpep-Gd nanoprobe in lesions, making it a highly efficient contrast agent for magnetic resonance (MR) and photoacoustic (PA) dual-modal imaging atherosclerotic plaque. Concurrently, the melanin nanoparticles function as a therapeutic agent by scavenging multiple toxic reactive oxygen species (ROS), inhibiting the pro-inflammatory cytokines expression, and significantly reducing the foam cell formation. As a result, NE/MNPpep remarkably alleviates atherosclerosis progression by a 24.7 % reduction for plaque area in ApoE-/- mice. Immunohistochemical analysis confirmed that NE/MNPpep treatment significantly reduced the macrophage content by 21.3 % and lipid burden by 15.6 % in plaques. In conclusion, our innovative nanoagent actively targets atherosclerotic sites, offers a noninvasive approach for identifying high-risk atherosclerotic plaques, and significantly contributes to the alleviation of lesion development in ApoE-/- mice. STATEMENT OF SIGNIFICANCE: Effective identification and inhibition of high-risk plaque progression hold clinical importance. However, it remains a major challenge due to the insufficient targeting of theranostic agents to plaques. Herein, a biomimetic nanoplatform is developed to actively target atherosclerosis plaque with the assistance of neutrophils, thereby minimizing off-target effects. Then, overexpressed MMP2 in high-risk plaques trigger the aggregation of hydrophobic Gd3+-labeled melanin nanoparticles, enhancing both MRI/PAI intensities for precise diagnosis. Additionally, the native antioxidant activity of melanin reduces inflammatory level, alleviates oxidative damage, and inhibits plaque progression in ApoE-/- mice. This study offers valuable insights for accurate plaque assessment and provides effective guidance for subsequent management strategies.

Melanin/melanin-like nanoparticles in tumor photothermal and targeted therapies

Melanin is a pigment found in nature that has good photothermal conversion qualities as well as stability, adaptability, and ease of manufacture. In addition to displaying the inherent properties of melanin, melanin/melanin-like nanoparticles (NPs) also have strong dispersion stability, excellent biocompatibility and biodegradability. Melanin/melanin-like NPs have been extensively studied for tumor therapy due to their unique photothermal properties and ability to target tumor cells. They have demonstrated particular promise in photothermal therapy of cancers. Using photothermal conversion materials to create a thermal effect by light irradiation, photothermal therapy (PTT) is a therapeutic approach that kills tumor cells locally. In this paper, we firstly review the preparation methods and physicochemical properties of melanin/melanin-like NPs, and then systematically and in-depth describe the recent advances of melanin/melanin-like NPs, especially synthetic polydopamine (PDA) melanin, in oncology applications, mainly focusing on tumor photothermal and targeted therapies. In addition, we summarize the advantages of melanin/melanin-like NPs in improving the efficacy of photothermal therapy, reducing toxic side effects, and enhancing tumor targeting, and discuss the current challenges and future directions.

Polymer-Based Drug Delivery Systems for Cancer Therapeutics

Chemotherapy together with surgery and/or radiotherapy are the most common therapeutic methods for treating cancer. However, the off-target effects of chemotherapy are known to produce side effects and dose-limiting toxicities. Novel delivery platforms based on natural and synthetic polymers with enhanced pharmacokinetic and therapeutic potential for the treatment of cancer have grown tremendously over the past 10 years. Polymers can facilitate selective targeting, enhance and prolong circulation, improve delivery, and provide the controlled release of cargos through various mechanisms, including physical adsorption, chemical conjugation, and/or internal loading. Notably, polymers that are biodegradable, biocompatible, and physicochemically stable are considered to be ideal delivery carriers. This biomimetic and bio-inspired system offers a bright future for effective drug delivery with the potential to overcome the obstacles encountered. This review focuses on the barriers that impact the success of chemotherapy drug delivery as well as the recent developments based on natural and synthetic polymers as platforms for improving drug delivery for treating cancer.

Biomedical applications of PLGA nanoparticles in nanomedicine: advances in drug delivery systems and cancer therapy

INTRODUCTION

During the last decades, the ever-increasing proportion of patients with cancer has been led to serious concerns worldwide. Therefore, the development and use of novel pharmaceuticals, like nanoparticles (NPs)-based drug delivery systems (DDSs), can be potentially effective in cancer therapy.

AREA COVERED

Poly lactic-co-glycolic acid (PLGA) NPs, as a kind of bioavailable, biocompatible, and biodegradable polymers, have approved by the Food and Drug Administration (FDA) for some biomedical and pharmaceutical applications. PLGA is comprised of lactic acid (LA) and glycolic acid (GA) and their ratio could be controlled during various syntheses and preparation approaches. LA/GA ratio determines the stability and degradation time of PLGA; lower content of GA results in fast degradation. There are several approaches for preparing PLGA NPs that can affect their various aspects, such as size, solubility, stability, drug loading, pharmacokinetics, and pharmacodynamics, and so on.

EXPERT OPINION

These NPs have indicated the controlled and sustained drug release in the cancer site and can use in passive and active (via surface modification) DDSs. This review aims to provide an overview of PLGA NPs, their preparation approach and physicochemical aspects, drug release mechanism and the cellular fate, DDSs for efficient cancer therapy, and status in the pharmaceutical industry and nanomedicine.

Melanin theranostic nanoplatform as an efficient drug delivery system for imaging-guided renal fibrosis therapy

As renal fibrosis nanotherapeutics, the endogenous biomaterial melanin not only has natural biocompatibility and biodegradability but also has inherent photoacoustic imaging ability and certain anti-inflammatory effects. These properties determine that melanin can not only as a carrier of medication but also track the biodistribution and renal uptake of drugs in vivo by photoacoustic imaging in real-time. Curcumin is a natural compound with biological activity, which has excellent ROS scavenging ability and good anti-inflammatory property. These materials appear more advantages in the development of nanoscale diagnostic and therapeutic platforms for future clinical translation. Herein, this study developed curcumin-loaded melanin nanoparticles (MNP-PEG-CUR NPs) as an efficient medication delivery system for photoacoustic imaging guidance renal fibrosis treatment. The nanoparticles are about 10 nm in size, exhibit good renal clearance efficiency, excellent photoacoustic imaging ability, and good in vitro and in vivo biocompatibility. These preliminary results indicated that MNP-PEG-CUR have clinically applicable potential as a therapeutic nanoplatform for renal fibrosis.

Dual-modality and Noninvasive Diagnostic of MNP-PEG-Mn Nanoprobe for Renal Fibrosis Based on Photoacoustic and Magnetic Resonance Imaging

To date, imaging-guided multimodality therapy is important to improve the accuracy of the diagnosis of renal fibrosis, and nanoplatforms for imaging-guided multimodality diagnosis are gaining more and more attention. There are many limitations and deficiencies in clinical use for early-stage diagnosis of renal fibrosis, and multimodal imaging can contribute more thoroughly and provide in-detail information for effective clinical diagnosis. Melanin is an endogenous biomaterial, and we developed an ultrasmall particle size melanin nanoprobe (MNP-PEG-Mn) based on photoacoustic (PA) and magnetic resonance (MR) dual-modal imaging. MNP-PEG-Mn nanoprobe, with the average diameter about 2.7 nm, can be passively targeted for accumulation in the kidney, and it has excellent free radical scavenging and antioxidant abilities without further exacerbating renal fibrosis. Using the normal group signal as a control, the dual-modal imaging results showed that the MR imaging (MAI) and PA imaging (PAI) signals reached the strongest at 6 h when MNP-PEG-Mn entered the 7 day renal fibrosis group via the left vein of the tail end of the mice; however, the strength of the dual-modal imaging signal and the gradient of signal change were significantly weaker in the 28 day renal fibrosis group than in the 7 day renal fibrosis group and normal group. The phenomenon preliminarily indicates that as a PAI/MRI dual-modality contrast medium candidate, MNP-PEG-Mn has outstanding ability in clinical application potential.

Protein-Caged Nanoparticles: A Promising Nanomedicine Against Cancer

Cancer is a severe threat to human wellness. A broad range of nanoparticles (NPs) have been developed to treat cancer. Given their safety profile, natural biomolecules such as protein-based NPs (PNPs) are promising substitutes for synthetic NPs that are currently used in drug delivery systems. In particular, PNPs have diverse characteristics and are monodisperse, chemically and genetically changeable, biodegradable, and biocompatible. To promote their application in clinical settings, PNPs must be precisely fabricated to fully exploit their advantages. This review highlights the different types of proteins that can be used to produce PNPs. Additionally, the recent applications of these nanomedicines and their therapeutic benefits against cancer are explored. Several future research directions that can facilitate the clinical application of PNPs are suggested.

Melanin-like nanoparticles: advances in surface modification and tumour photothermal therapy

Currently, tumor treatments are characterized by intelligence, diversity and personalization, but the therapeutic reagents used are often limited in clinical efficacy due to problems with water solubility, targeting, stability and multidrug resistance. To remedy these shortcomings, the application of multifunctional nanotechnology in the biomedical field has been widely studied. Synthetic melanin nanoparticles (MNPs) surfaces which contain highly reactive chemical groups such as carboxyl, hydroxyl and amine groups, can be used as a reaction platform on which to graft different functional components. In addition, MNPs easily adhere to substrate surface, and serve as a secondary reaction platform to modify it. The multifunctionality and intrinsic biocompatibility make melanin-like nanoparticles promising as a multifunctional and powerful nanoplatform for oncological applications. This paper first reviews the preparation methods, polymerization mechanisms and physicochemical properties of melanin including natural melanin and chemically synthesized melanin to guide scholars in MNP-based design. Then, recent advances in MNPs especially synthetic polydopamine (PDA) melanin for various medical oncological applications are systematically and thoroughly described, mainly focusing on bioimaging, photothermal therapy (PTT), and drug delivery for tumor therapy. Finally, based on the investigated literature, the current challenges and future directions for clinical translation are reasonably discussed, focusing on the innovative design of MNPs and further elucidation of pharmacokinetics. This paper is a timely and comprehensive and detailed study of the progress of MNPs in tumor therapy, especially PTT, and provides ideas for the design of personalized and customizable oncology nanomedicines to address the heterogeneity of the tumor microenvironment.