Multifunction in One Nanoparticle for Anticancer Therapy: Bowl-Shaped Au@PDA Yolk-Shell NPs

Material and Design Toolkit for Drug Delivery: State of the Art, Trends, and Challenges

The nanomaterial and related toolkit have promising applications for improving human health and well-being. Nanobased drug delivery systems use nanoscale materials as carriers to deliver therapeutic agents in a targeted and controlled manner, and they have shown potential to address issues associated with conventional drug delivery systems. They offer benefits for treating various illnesses by encapsulating or conjugating biological agents, chemotherapeutic drugs, and immunotherapeutic agents. The potential applications of this technology are vast; however, significant challenges exist to overcome such as safety issues, toxicity, efficacy, and insufficient capacity. This article discusses the latest developments in drug delivery systems, including drug release mechanisms, material toolkits, related design molecules, and parameters. The concluding section examines the limitations and provides insights into future possibilities.

Actively targeted gold-polydopamine (PDA@Au) nanocomplex for sequential drug release and combined synergistic chemo-photothermal therapeutic effects

Multifunctional nanoparticles for treatment in cancer are getting more and more attention recently. In this study, we employed a novel polydopamine (PDA) framework-based gold nanoparticles as a carrier of an antimetabolite drug, 5-Fluorouracil (5-FU). Folic acid (FA) was embellished onto the surface of nanoparticle imparting the nanosystem with remarkable tumor-targeting abilities through its precise binding with FA receptor that is notably overexpressed in breast cancer cells. PDA served as a photothermal treatment (PTT) agent and a gatekeeper to regulate drug release since it is highly pH-sensitive and might lengthen the residency period while simultaneously enhancing water solubility and biological compatibility of nanomaterials. Gold nanoparticles (Au NPs) end up serving as both a drug delivery platform and a source of substantial photothermal effects, culminating in synergistically coupled chemo-photothermal therapy. The PDA@Au@FA nanocomplex, loaded with 5-FU, is biocompatible, features strong NIR absorption and photothermal conversion, and can control drug release in pH/NIR dual response environment. The cell viability in PDA@Au@5-FU-FA group with NIR irradiation in 48 h was only 20.1 ± 2.6%. In addition, apoptosis staining experiments revealed greater cellular uptake of PDA@Au@5-FU-FA by MCF-7 cells. Therefore, PDA@Au@5-FU-FA nanocomplex that we postulated herein may be a potential contender for effective curative treatment for breast cancer.

Polymeric Bowl-Shaped Nanoparticles: Hollow Structures with a Large Opening on the Surface

Polymeric bowl-shaped nanoparticles (BNPs) are anisotropic hollow structures with large openings on the surface, which have shown advantages such as high specific area and efficient encapsulation, delivery and release of large-sized cargoes on demand compared to solid nanoparticles or closed hollow structures. Several strategies have been developed to prepare BNPs based on either template or template-free methods. For instance, despite the widely used self-assembly strategy, alternative methods including emulsion polymerization, swelling and freeze-drying of polymeric spheres, and template-assisted approaches have also been developed. It is attractive but still challenging to fabricate BNPs due to their unique structural features. However, there is still no comprehensive summary of BNPs up to now, which significantly hinders the further development of this field. In this review, the recent progress of BNPs will be highlighted from the perspectives of design strategies, preparation methods, formation mechanisms, and emerging applications. Moreover, the future perspectives of BNPs will also be proposed.

Aqueous green synthesis of organic/inorganic nanohybrids with an unprecedented synergistic mechanism for enhanced near-infrared photothermal performance

Silver sulfide (Ag2S) nanoparticles (NPs) represent one of the most popular inorganic reagents for near-infrared (NIR) photothermal therapy (PTT). However, the extensive biomedical applications of Ag2S NPs are greatly compromised by the hydrophobicity of the NPs prepared in organic solvents, their low photothermal conversion efficiency, certain surface modification-induced damage to their intrinsic properties and short circulation time. To develop a facile yet efficient green approach to overcome these shortcomings for improved properties and performance of Ag2S NPs, we report herein the construction of Ag2S@polydopamine (PDA) nanohybrids via a "one-pot" organic-inorganic hybridization strategy, which produces uniform Ag2S@PDA nanohybrids with well-modulated sizes in the range of 100-300 nm via the self-polymerization of dopamine (DA) and subsequent synergistic assembly of PDA with Ag2S NPs in a three-phase mixed medium containing water, ethanol and trimethylbenzene (TMB). Integration of dual photothermal moieties, i.e., Ag2S and PDA at a molecular level, endows Ag2S@PDA nanohybrids with synergistically enhanced NIR photothermal properties that are much better than those of either PDA or Ag2S NPs due to calculated combination indexes (CIs) of 0.3-0.7 between Ag2S NPs and PDA based on a modified Chou-Talalay method. Therefore, this study not only developed a facile "one-pot" green approach toward producing uniform Ag2S@PDA nanohybrids with well-modulated dimensions, but also revealed an unprecedented synergistic mechanism for organic/inorganic nanohybrids that is based on dual photothermal moieties providing enhanced near-infrared photothermal performance.

Biosafety risk assessment of gold and aluminum nanoparticles in tumor-bearing mice

To improve the biosafety of the nanodelivery system, this study developed novel monodisperse spherical aluminum nanoparticles (Al NPs) and evaluated their cytotoxicity in vitro and distribution and biotoxicity in vivo. Compared with gold nanoparticles of the same size, Al NPs not only had low cytotoxicity in vitro but also did not cause accumulation in major organs in vivo after intravenous injections. No significant abnormalities were observed in the serum biochemical indices of mice injected with Al NPs. Additionally, no substantial changes occurred in the histopathology of major organs, and no apparent biological toxicity was measured after consecutive injections of Al NPs. These results indicate that Al NPs have a good biological safety and provide a new method for developing low-toxicity nanomedicine.

Reaching new lights: a review on photo-controlled nanomedicines and their in vivo evaluation

The selective and efficient delivery of bioactive molecules to sites of interest remains a formidable challenge in medicine. In recent years, it has been shown that stimuli-responsive drug delivery systems display several advantages over traditional drug administration such as an improved pharmacokinetic profile and the desirable ability to gain control over release. Light emerged as one of the most powerful stimuli due to its high biocompatibility, spatio-temporal control, and non-invasiveness. On the road to clinical translation, various chemical systems of high complexity have been reported with the aim to improve efficacy, safety, and versatility of drug delivery under complex biological conditions. For future research on the chemical design of such photo-controlled nanomedicines, it is essential to gain an understanding of their in vivo translation and efficiency. Here, we discuss photo-controlled nanomedicines that have been evaluated in vivo and provide an overview of the state-of-the-art that should guide future research design.

Smart Chemical Oxidative Polymerization Strategy To Construct Au@PPy Core-Shell Nanoparticles for Cancer Diagnosis and Imaging-Guided Photothermal Therapy

Imaging-guided photothermal therapy (PTT) in a single nanoscale platform has aroused extensive research interest in precision medicine, yet only a few methods have gained wide acceptance. Thus, it remained an urgent need to facilely develop biocompatible and green probes with excellent theranostic capacity for superior biomedical applications. In this study, a smart chemical oxidative polymerization strategy was successfully developed for the synthesis of Au@PPy core-shell nanoparticles with polyvinyl alcohol (PVA) as the hydrophile. In the reaction, the reactant tetrachloroauric acid (HAuCl₄) was reduced by pyrrole to fabricate a gold (Au) core, and pyrrole was oxidized to deposit around the Au core to form a polypyrrole (PPy) shell. The as-synthesized Au@PPy nanoparticles showed a regular core-shell morphology and good colloidal stability. Relying on the high X-ray attenuation of Au and strong near-infrared (NIR) absorbance of PPy and Au, Au@PPy nanoparticles exhibited excellent performance in blood pool/tumor imaging and PTT treatment by a series of in vivo experiments, in which tumor could be precisely positioned and thoroughly eradicated. Hence, the facile chemical oxidative polymerization strategy for constructing monodisperse Au@PPy core-shell nanoparticles with potential for cancer diagnosis and imaging-guided photothermal therapy shed light on an innovative design concept for the facile fabrication of biomedical materials.

Frontiers in Preparations and Promising Applications of Mesoporous Polydopamine for Cancer Diagnosis and Treatment

Polydopamine (PDA) is a natural melanin derived from marine mussels that has good biocompatibility, biodegradability, and photothermal conversion ability. As a new coating material, it offers a novel way to modify the surface of various substances. The drug loading capacity and encapsulation efficiency of PDA are greatly improved via the use of mesoporous materials. The abundant pore canals on mesoporous polydopamine (MPDA) exhibit a uniquely large surface area, which provides a structural basis for drug delivery. In this review, we systematically summarized the characteristics and manufacturing process of MPDA, introduced its application in the diagnosis and treatment of cancer, and discussed the existing problems in its development and clinical application. This comprehensive review will facilitate further research on MPDA in the fields of medicine including cancer therapy, materials science, and biology.

Bimetallic Nanomaterials: A Promising Nanoplatform for Multimodal Cancer Therapy

Bimetallic nanomaterials (BMNs) composed of two different metal elements have certain mixing patterns and geometric structures, and they often have superior properties than monometallic nanomaterials. Bimetallic-based nanomaterials have been widely investigated and extensively used in many biomedical fields especially cancer therapy because of their unique morphology and structure, special physicochemical properties, excellent biocompatibility, and synergistic effect. However, most reviews focused on the application of BMNs in cancer diagnoses (sensing, and imaging) and rarely mentioned the application of the treatment of cancer. The purpose of this review is to provide a comprehensive perspective on the recent progress of BNMs as therapeutic agents. We first introduce and discuss the synthesis methods, intrinsic properties (size, morphology, and structure), and optical and catalytic properties relevant to cancer therapy. Then, we highlight the application of BMNs in cancer therapy (e.g., drug/gene delivery, radiotherapy, photothermal therapy, photodynamic therapy, enzyme-mediated tumor therapy, and multifunctional synergistic therapy). Finally, we put forward insights for the forthcoming in order to make more comprehensive use of BMNs and improve the medical system of cancer treatment.

Targeted Recruitment and Degradation of Estrogen Receptor α by Photothermal Polydopamine Nanoparticles for Breast Tumor Ablation

The major challenges of photothermal therapy (PTT) toward clinical application are the severe skin injury and inflammation response associated with high power laser irradiation. Herein, polydopamine nanoparticles (PDA-EST and PDA-RAL) targeted to estrogen receptor α (ERα) for efficient ablation of breast tumor under a low irradiation density of 0.1 W cm^-2 are reported. These nanoparticles are capable of recruiting ERα on their surface and induce a complete ERα degradation via localized heat. Owing to the ERα targetability, PDA-EST and PDA-RAL strongly suppress the proliferation of breast cancer cells without causing significant inflammation. This work provides a generalized method for enhancing PTT efficacy under low irradiation density.