Physical, Chemical, and Biological Structures based on ROS-Sensitive Moieties that are Able to Respond to Oxidative Microenvironments

Functionalised collagen spheres reduce H2O2 mediated apoptosis by scavenging overexpressed ROS

Excess reactive oxygen species (ROS) has been implicated in numerous diseases including cancer, cardiovascular and neurodegenerative diseases. Overexpression of ROS can lead to oxidative stress and subsequently to H₂O₂-mediated cell apoptosis. In this study, it was demonstrated that biodegradable PLGA microspheres coated with collagen type I and decorated with MnO₂ nanoparticles acted as ROS scavengers controlling the H₂O₂-mediated apoptosis of cells undergoing oxidative stress. The results showed that the functionalized collagen spheres can protect cells even under very harsh conditions of oxidative stress.

Mitochondria-targeting Au nanoclusters enhance radiosensitivity of cancer cells

Radiotherapy is an important technology for the clinical treatment of cancer, but the patients suffer from the severe side effects after exposure to radiation. There is an urgent need to develop theranostic agents with excellent imaging capability and effective radiosensitization in order to minimize X-ray irradiation. Herein, we report an approach to synthesize peptide-templated Au nanoclusters (AuNCs) for theranostic radiosensitization. A new peptide (CCYKFR) is designed for the preparation of AuNCs with uniform size distribution and fluorescence (656 nm) of high photostability. CCYKFR-AuNCs feature highly efficient targeting/accumulation on mitochondria after endocytosis. With a series of experiments, we demonstrate that CCYKFR-AuNCs irradiated by 4 Gy X-rays can introduce a burst of mitoROS and severe DNA damage leading to cancer cell death. This study presents an important strategy to design theranostic nanomaterials with improved radiosensitization for the development of new anti-cancer therapies.

Facile Synthesis of H2O2-Cleavable Poly(ester-amide)s by Passerini Multicomponent Polymerization

We report the straightforward synthesis of two types of H₂O₂-cleavable poly(ester-amide)s (P1 and P2) via the Passerini multicomponent polymerization (P-MCP) of 4-formylbenzeneboronic acid pinacol ester with 1,6-diisocyanohexane and 1,6-hexanedioic acid or a polyethylene glycol (PEG) dicarboxylic acid. The H₂O₂-cleavable phenylboronic acid ester was integrated into the polymer backbone by the in situ formed benzyl ester bond. GPC and ¹H NMR confirmed the complete H₂O₂-triggered degradation of these polymers in aqueous medium by a mechanism of sequential oxidation of phenylboronic acid ester and self-immolative elimination. Compared with the hydrophobic polymer P1, the PEG-based water-soluble polymer P2 degraded much faster even at a lower H₂O₂ concentration. Cytocompatible nanoparticles of polymer P1 loaded with fluorescent Nile red were fabricated, and controlled release of Nile red in response to H₂O₂ was achieved, thus, demonstrating the utility of these polymers as potential H₂O₂-responsive delivery vehicles.

The Role of Reactive Oxygen Species (ROS) in the Biological Activities of Metallic Nanoparticles

Nanoparticles (NPs) possess unique physical and chemical properties that make them appropriate for various applications. The structural alteration of metallic NPs leads to different biological functions, specifically resulting in different potentials for the generation of reactive oxygen species (ROS). The amount of ROS produced by metallic NPs correlates with particle size, shape, surface area, and chemistry. ROS possess multiple functions in cellular biology, with ROS generation a key factor in metallic NP-induced toxicity, as well as modulation of cellular signaling involved in cell death, proliferation, and differentiation. In this review, we briefly explained NP classes and their biomedical applications and describe the sources and roles of ROS in NP-related biological functions in vitro and in vivo. Furthermore, we also described the roles of metal NP-induced ROS generation in stem cell biology. Although the roles of ROS in metallic NP-related biological functions requires further investigation, modulation and characterization of metallic NP-induced ROS production are promising in the application of metallic NPs in the areas of regenerative medicine and medical devices.

Synthesis of a phenylboronic ester-linked PEG-lipid conjugate for ROS-responsive drug delivery

A kind of phenylboronic ester-linked PEG-lipid conjugate was designed and synthesized for ROS-responsive drug delivery.

H2O2-Responsive mesoporous silica nanoparticles integrated with microneedle patches for the glucose-monitored transdermal delivery of insulin

We successfully developed a microneedle patch system integrated with H₂O₂-responsive mesoporous silica nanoparticles for the glucose-monitored transdermal delivery of insulin.

Serum-resistant, reactive oxygen species (ROS)-potentiated gene delivery in cancer cells mediated by fluorinated, diselenide-crosslinked polyplexes

Fluorinated, diselenide-crosslinked polyplexes were developed to enable ROS-responsive and serum-resistant gene delivery in cancer cells.

Reactive oxygen species generating systems meeting challenges of photodynamic cancer therapy

The reactive oxygen species (ROS)-mediated mechanism is the major cause underlying the efficacy of photodynamic therapy (PDT). The PDT procedure is based on the cascade of synergistic effects between light, a photosensitizer (PS) and oxygen, which greatly favors the spatiotemporal control of the treatment. This procedure has also evoked several unresolved challenges at different levels including (i) the limited penetration depth of light, which restricts traditional PDT to superficial tumours; (ii) oxygen reliance does not allow PDT treatment of hypoxic tumours; (iii) light can complicate the phototherapeutic outcomes because of the concurrent heat generation; (iv) specific delivery of PSs to sub-cellular organelles for exerting effective toxicity remains an issue; and (v) side effects from undesirable white-light activation and self-catalysation of traditional PSs. Recent advances in nanotechnology and nanomedicine have provided new opportunities to develop ROS-generating systems through photodynamic or non-photodynamic procedures while tackling the challenges of the current PDT approaches. In this review, we summarize the current status and discuss the possible opportunities for ROS generation for cancer therapy. We hope this review will spur pre-clinical research and clinical practice for ROS-mediated tumour treatments.