Nano-drug delivery system targeting tumor microenvironment: A prospective strategy for melanoma treatment

Melanoma, the most aggressive form of cutaneous malignancy arising from melanocytes, is frequently characterized by metastasis. Despite considerable progress in melanoma therapies, patients with advanced-stage disease often have a poor prognosis due to the limited efficacy, off-target effects, and toxicity associated with conventional drugs. Nanotechnology has emerged as a promising approach to address these challenges with nanoparticles capable of delivering therapeutic agents specifically to the tumor microenvironment (TME). However, the clinical approval of nanomedicines for melanoma treatment remains limited, necessitating further research to develop nanoparticles with improved biocompatibility and precise targeting capabilities. This comprehensive review provides an overview of the current research on nano-drug delivery systems for melanoma treatment, focusing on liposomes, polymeric nanoparticles, and inorganic nanoparticles. It discusses the potential of these nanoparticles for targeted drug delivery, as well as their ability to enhance the efficacy of conventional drugs while minimizing toxicity. Furthermore, this review emphasizes the significance of interdisciplinary collaboration between researchers from various fields to advance the development of nanomedicines. Overall, this review serves as a valuable resource for researchers and clinicians interested in the potential of nano-drug delivery systems for melanoma treatment and offers insights into future directions for research in this field.

Light-Interacting iron-based nanomaterials for localized cancer detection and treatment

To improve the prognosis of cancer patients, methods of local cancer detection and treatment could be implemented. For that, iron-based nanomaterials (IBN) are particularly well-suited due to their biocompatibility and the various ways in which they can specifically target a tumor, i.e. through passive, active or magnetic targeting. Furthermore, when it is needed, IBN can be associated with well-known fluorescent compounds, such as dyes, clinically approved ICG, fluorescent proteins, or quantum dots. They may also be excited and detected using well-established optical methods, relying on scattering or fluorescent mechanisms, depending on whether IBN are associated with a fluorescent compound or not. Systems combining IBN with optical methods are diverse, thus enabling tumor detection in various ways. In addition, these systems provide a wealth of information, which is inaccessible with more standard diagnostic tools, such as single tumor cell detection, in particular by combining IBN with near-field scanning optical microscopy, dark-field microscopy, confocal microscopy or super-resolution microscopy, or the highlighting of certain dynamic phenomena such as the diffusion of a fluorescent compound in an organism, e.g. using fluorescence lifetime imaging, fluorescence resonance energy transfer, fluorescence anisotropy, or fluorescence tomography. Furthermore, they can in some cases be complemented by a therapeutic approach to destroy tumors, e.g. when the fluorescent compound is a drug, or when a technique such as photo-thermal or photodynamic therapy is employed. This review brings forward the idea that iron-based nanomaterials may be associated with various optical techniques to form a commercially available toolbox, which can serve to locally detect or treat cancer with a better efficacy than more standard medical approaches. STATEMENT OF SIGNIFICANCE: New tools should be developed to improve cancer treatment outcome. For that, two closely-related aspects deserve to be considered, i.e. early tumor detection and local tumor treatment. Here, I present various types of iron-based nanomaterials, which can achieve this double objective when they interact with a beam of light under specific and accurately chosen conditions. Indeed, these materials are biocompatible and can be used/combined with most standard microscopic/optical methods. Thus, these systems enable on the one hand tumor cell detection with a high sensitivity, i.e. down to single tumor cell level, and on the other hand tumor destruction through various mechanisms in a controlled and localized manner by deciding whether or not to apply a beam of light and by having these nanomaterials specifically target tumor cells.

Iron-Based Catalytically Active Complexes in Preparation of Functional Materials

Iron complexes are particularly interesting as catalyst systems over the other transition metals (including noble metals) due to iron’s high natural abundance and mediation in important biological processes, therefore making them non-toxic, cost-effective, and biocompatible. Both homogeneous and heterogeneous catalysis mediated by iron as a transition metal have found applications in many industries, including oxidation, C-C bond formation, hydrocarboxylation and dehydration, hydrogenation and reduction reactions of low molecular weight molecules. These processes provided substrates for industrial-scale use, e.g., switchable materials, sustainable and scalable energy storage technologies, drugs for the treatment of cancer, and high molecular weight polymer materials with a predetermined structure through controlled radical polymerization techniques. This review provides a detailed statement of the utilization of homogeneous and heterogeneous iron-based catalysts for the synthesis of both low and high molecular weight molecules with versatile use, focusing on receiving functional materials with high potential for industrial application.

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and pKa values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.

An ultrasensitive fluorescent aptasensor based on truncated aptamer and AGET ATRP for the detection of bisphenol A

Given the gigantic harmfulness of bisphenol A (BPA), a novel and ultrasensitive aptasensor, which employs the truncated BPA aptamer, click chemistry, and activators generated by electron transfer for atom transfer radical polymerization (AGET ATRP), was developed herein for the quantitative determination of BPA. Firstly, hairpin DNAs (hairpins) with a thiol at the 5' end and an azide group at the 3' end were conjugated with aminated magnetic beads (MBs) through heterobifunctional cross-linkers. BPA truncated aptamer (ssDNA-A) hybridizes with its complementary single-stranded DNA (ssDNA-B) to form double-stranded DNA. In the presence of BPA, ssDNA-A specifically captures BPA, and then ssDNA-B is released. Subsequently, the ssDNA-B hybridizes with hairpins to expose the azide group near the surface of the MBs. Then, propargyl-2-bromoisobutyrate (PBIB), the initiator of AGET ATRP containing alkynyl group, was conjugated with azide group of hairpins via the Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC). Consequently, a large number of fluorescein-o-acrylate (FA) were introduced to the MBs through AGET ATRP, resulting in that the fluorescence intensity was increased dramatically. Obviously, the fluorescence intensity was especially sensitive to the change of BPA concentration, and this method can be used in quantitative determination of BPA. Under optimal conditions, a broad liner range from 100 fM to 100 nM and a low limit of detection (LOD) of 6.6 fM were obtained. Moreover, the method exhibits not only excellent specificity for BPA detection over BPA analogues but high anti-interference ability in real water sample detection, indicating that it has huge application prospect in food safety and environment monitoring.

A pH-sensitive near-infrared fluorescent probe with alkaline pKa for chronic wound monitoring in diabetic mice

An alkaline pH-sensitive near-infrared fluorescent probe can monitor pH changes in the course of chronic wound development in mice.

Construction of dual-functional polymer nanomaterials with near-infrared fluorescence imaging and polymer prodrug by RAFT-mediated aqueous dispersion polymerization

The performance of functional polymer nanomaterials is a vigorously discussed topic in polymer science. We devoted ourselves to investigating polymer nanomaterials based on near-infrared (NIR) fluorescence imaging and polymer prodrug in this study. Aza-boron dipyrromethene (BODIPY) is an important organic dye, having characteristics such as environmental resistance, light resistance, high molar extinction coefficient, and fluorescence quantum yield. We incorporated it into our target monomer, which can be polymerized without changing its parent structure in a polar solvent and copolymerized with water-soluble monomer to improve the solubility of the dye in an aqueous solution. At the same time, the hydrophobic drug camptothecin (CPT) was designed as a prodrug monomer, and the polymeric nanoparticles (NPs) with NIR fluorescence imaging and prodrug were synthesized in situ in reversible addition-fragmentation chain transfer (RAFT)-mediated aqueous dispersion polymerization. The dynamic light scattering (DLS) and transmission electron microscopy (TEM) revealed the final uniform size of the dual-functional polymeric NPs morphology. The dual-functional polymeric NPs had a strong absorption and emission signal in the NIR region (>650 nm) based on the fluorescence tests. In consideration of the long-term biological toxicity, confocal laser scanning microscopy (CLSM) results indicated that the dual-functional NPs with controlled drug content exhibited effective capability of killing HeLa cells. In addition, in vivo imaging of the dual-functional NPs was observed in real time, and the fluorescent signals clearly demonstrated the dynamic process of prodrug transfer.

Surface modification of carbon nanotubes by using iron-mediated activators generated by electron transfer for atom transfer radical polymerization

Herein, a surface-initiated activator generated by electron transfer for an atom transfer radical polymerization (AGET ATRP) system was developed on the surface of multiwall carbon nanotubes (MWCNTs) by using FeCl3·6H2O as the catalyst, tris-(3,6-dioxoheptyl) amine (TDA-1) as the ligand and ascorbic acid (AsAc) as the reducing agent. A wide range of polymers, such as polystyrene (PS), poly(methyl methacrylate) (PMMA) and poly(poly(ethylene glycol) methyl ether methacrylate) (PPEGMA), were successfully grafted onto the surfaces. The core-shell structure of MWCNTs@PS was observed by TEM. Both Raman spectra and the results of hydrolysis of MWCNTs@PS (after extraction by THF) confirmed that the PS chains were covalently tethered onto the surfaces of the MWCNTs. Due to superior biocompatibility of the iron catalyst, the strategy of modification of MWCNTs via iron-mediated AGET ATRP provided a promising method for the controllable and biocompatible modification of nanomaterials.

Surface-Initiated Controlled Radical Polymerization: State-of-the-Art, Opportunities, and Challenges in Surface and Interface Engineering with Polymer Brushes

The generation of polymer brushes by surface-initiated controlled radical polymerization (SI-CRP) techniques has become a powerful approach to tailor the chemical and physical properties of interfaces and has given rise to great advances in surface and interface engineering. Polymer brushes are defined as thin polymer films in which the individual polymer chains are tethered by one chain end to a solid interface. Significant advances have been made over the past years in the field of polymer brushes. This includes novel developments in SI-CRP, as well as the emergence of novel applications such as catalysis, electronics, nanomaterial synthesis and biosensing. Additionally, polymer brushes prepared via SI-CRP have been utilized to modify the surface of novel substrates such as natural fibers, polymer nanofibers, mesoporous materials, graphene, viruses and protein nanoparticles. The last years have also seen exciting advances in the chemical and physical characterization of polymer brushes, as well as an ever increasing set of computational and simulation tools that allow understanding and predictions of these surface-grafted polymer architectures. The aim of this contribution is to provide a comprehensive review that critically assesses recent advances in the field and highlights the opportunities and challenges for future work.

Photocatalyzed iron-based ATRP of methyl methacrylate using 1,3-dimethyl-2-imidazolidinone as both solvent and ligand

A simple photocatalyzed Fe-based ATRP of MMA was conducted under UV irradiation using the “green” solvent DMI as both the solvent and ligand.

Imaging the Tumor Microenvironment

The tumor microenvironment consists of tumor, stromal, and immune cells, as well as extracellular milieu. Changes in numbers of these cell types and their environments have an impact on cancer growth and metastasis. Non-invasive imaging of aspects of the tumor microenvironment can provide important information on the aggressiveness of the cancer, whether or not it is metastatic, and can also help to determine early response to treatment. This chapter provides an overview on non-invasive in vivo imaging in humans and mouse models of various cell types and physiological parameters that are unique to the tumor microenvironment. Current clinical imaging and research investigation are in the areas of nuclear imaging (positron emission tomography (PET) and single photon emission computed tomography (SPECT)), magnetic resonance imaging (MRI) and optical (near infrared (NIR) fluorescence) imaging. Aspects of the tumor microenvironment that have been imaged by PET, MRI and/or optical imaging are tumor associated inflammation (primarily macrophages and T cells), hypoxia, pH changes, as well as enzymes and integrins that are highly prevalent in tumors, stroma and immune cells. Many imaging agents and strategies are currently available for cancer patients; however, the investigation of novel avenues for targeting aspects of the tumor microenvironment in pre-clinical models of cancer provides the cancer researcher with a means to monitor changes and evaluate novel treatments that can be translated into the clinic.

pH-Responsive near-infrared fluorescent cyanine dyes for molecular imaging based on pH sensing

pH-Responsive near-infrared cyanine dyes were synthesized and applied as imaging probes of acidic intracellular compartments of living cells.

Photosensitizer cross-linked nano-micelle platform for multimodal imaging guided synergistic photothermal/photodynamic therapy

The multifunctional nano-micelle platform holds great promise to enhance the accuracy and efficiency of cancer diagnosis and therapy. In this work, an amphiphilic poly[(poly(ethylene glycol) methyl ether methacrylate)-co-(3-aminopropyl methacrylate)]-block-poly(methyl methacrylate) (P(PEGMA-co-APMA)-b-PMMA) block copolymer was synthesized by successive RAFT polymerizations and subsequent chemical modification. Then the multifunctional micelles with high solubility in physiological environments were developed by a self-assembly and crosslinking processes. The photosensitizer segment, 5,10,15,20-tetrakis (4-carboxyphenyl) porphyrin (TCPP), serves as a tetra-functional cross-linker, photodynamic agent, fluorescence indicator, as well as magnetic resonance (MR) contrast agent after labelling with manganese ions (Mn(2+)), while IR825 simultaneously locating in the interior of the fabricated micelles contributed to the photoacoustic (PA) imaging ability and the photothermal effect. The prepared nanoparticles show great stability in a physiological environment with uniform morphology and diameters of around 80 nm as disclosed by stability investigation, TEM and DLS analysis. IR825@P(PEGMA-co-APMA)-b-PMMA@TCPP/Mn nanoparticles displayed high in vivo tumor uptake with a long blood circulation half-life (∼3.64 h) by the EPR effect after intravenous (i.v.) injection, as revealed by fluorescence, MR and PA imaging models. In vivo anti-tumor effects were achieved via a combined photothermal and photodynamic therapy without noticeable dark toxicity, and this strategy was able to induce a remarkably improved synergistic therapeutic effect to both superficial and deep regions of tumors under mild conditions compared with either single photothermal or photodynamic mechanisms.

Real-time monitoring of a controlled drug delivery system in vivo: construction of a near infrared fluorescence monomer conjugated with pH-responsive polymeric micelles

A self-assembled polymeric micelle from multifunctional amphiphilic copolymer with NIR and pH-sensitive groups can be used to monitor the dynamic process of its arriving at the tumor site in real time.

Metal-free photoinduced electron transfer–atom transfer radical polymerization (PET–ATRP) via a visible light organic photocatalyst

This work developed the first example of PET-ATRP using a reductive pathway, which provides new opportunities for the synthesis of well-controlled polymer architectures through a photochemical approach.

A Self-Assembled Albumin-Based Nanoprobe for In Vivo Ratiometric Photoacoustic pH Imaging

A photoacoustic nanoprobe is self-assembled from human serum albumin and two types of dye molecules, one is inert to pH and the other is pH sensitive. This probe and the quantitative ratiometric photoacoustic pH imaging method are shown to have high safety, be easy-to-operate, and have depth-independent accuracy for real-time in vivo pH imaging of entire tumors. These features make them promising for future cancer prognosis and therapeutic planning.

Self-assembly of BODIPY based pH-sensitive near-infrared polymeric micelles for drug controlled delivery and fluorescence imaging applications

Responsive block copolymer micelles emerging as promising imaging and drug delivery systems show high stability and on-demand drug release activities. Herein, we developed self-assembled pH-responsive NIR emission micelles entrapped with doxorubicin (DOX) within the cores by the electrostatic interactions for fluorescence imaging and chemotherapy applications. The block copolymer, poly(methacrylic acid)-block-poly[(poly(ethylene glycol) methyl ether methacrylate)-co-boron dipyrromethene derivatives] (PMAA-b-P(PEGMA-co-BODIPY), was synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization, and the molecular weight distribution of this copolymer was narrow (Mw/Mn = 1.31). The NIR fluorescence enhancement induced by the phenol/phenolate interconversion equilibrium works as a switch in response to the intracellular pH fluctuations. DOX-loaded PMAA-b-P(PEGMA-co-BODIPY) micelles can detect the physiological pH fluctuations with a pKa near physiological conditions (∼7.52), and showed pH-responsive collapse and an obvious acid promoted anticancer drug release behavior (over 58.8-62.8% in 10 h). Real-time imaging of intracellular pH variations was performed and a significant chemotherapy effect was demonstrated against HeLa cells.

Iron-mediated AGET ATRP with crown ether as both ligand and solvent

A facile iron-mediated AGET ATRP system suitable for a wide range of monomers was successfully developed with crown ether without any additional ligands.