Water-Dispersible Candle Soot-Derived Carbon Nano-Onion Clusters for Imaging-Guided Photothermal Cancer Therapy

Onion-like carbon based single-atom iron nanozyme for photothermal and catalytic synergistic antibacterial application

Nanozymes with oxidase (OXD)-like activity have emerged as promising antibacterial agents due to their capability of catalyzing atmospheric O2 to generate highly active free radicals. However, the precise engineering of functional nanozyme at the atomic level for antibacterial therapy presents a challenge. Here, atomically dispersed Fe atoms were loaded onto onion-like carbon (OLC) through a ligand-assisted calcination strategy, yielding a single-atom nanozyme (FeSA-OLC) with enhanced oxidase-like activity. The FeSA-OLC could catalyze the decomposition of O2 to produce active hydroxyl radicals (·OH) owing to the fully exposed Fe atoms and a highly curved carbon shell. Density functional theory calculation revealed that the single-atom Fe sites facilitated the generation of free radical species by promoting the adsorption and cleavage of OO bond. Meanwhile, the FeSA-OLC exhibited a notable photothermal conversion efficiency of 66.48% under near-infrared laser irradiation. Furthermore, in vitro experimental results demonstrated a synergistic antibacterial effect towards Escherichia coli due to the photothermal-enhanced oxidase-like activity. Overall, this work introduced a strategy to develop OLC-based single-atom nanozyme, thereby offering new avenues for photothermal-augmented antibacterial therapy.

Dual-action defense: A photothermal and controlled nitric oxide-releasing coating for preventing biofilm formation

Biofilms formed by pathogenic bacteria on biomedical devices and implants pose a considerable challenge due to their resistance to conventional treatments and their role in severe infections. Preventing biofilm formation is strategically more advantageous than attempting to eliminate the mature biofilms, particularly in addressing the persistence of such formations. In this context, a dual-action antibiofilm coating is developed, utilizing S-nitrosothiols functionalized candle soot (CS), which capitalizes on CS's strong light absorption for photothermal therapy and the controlled release of nitric oxide (NO) from S-nitrosothiols to inhibit biofilm formation. This coating exhibits stable and efficient light-to-heat conversion, along with the ability to release NO gradually at physiological temperatures and to rapidly release NO on demand when triggered by a near-infrared (NIR) laser. Under NIR irradition, the coating generates heat swiftly and releases substantial amounts of NO, which synergistically disrupts bacterial membranes, leading to the leakage of intracellular components and the effective eradication of surface-adhered bacteria. In the absence of NIR irradiation, the coating continuously releases low concentrations of NO, which depletes exopolysaccharides and impedes biofilm formation. The antibiofilm efficacy of this coating is assessed against Staphylococcus aureus and Pseudomonas aeruginosa, demonstrating marked reductions in bacterial viability and biofilm formation in vitro. Additionally, the coating exhibits minimal cytotoxicity and can be easily applied to diverse substrates. This study underscores the potential of this coating as a broad-spectrum, non-toxic approach for preventing biofilm-related complications in biomedical applications.

Onion-Like Carbon Nanozyme: Controlling Peroxidase-Like Activity by Carbon Hybridization Patterns for Antibacterial Therapy

Since the inception of the concept of nanozymes, there has been a growing interest in the rational design and controllable synthesis of nanozymes with adjustable activities. In this study, onion-liked carbon (OLC) with remarkable peroxidase-like (POD) activity are developed through delicately controlling the sp2/sp3 configuration. The investigation reveals that enzymatic activity of OLC increases first and then decreases with the increased graphitic degree, with the highest activity observed at a moderate sp2/sp3 ratio of 17.17%. A series of experiments and theoretical calculations are conducted to elucidate the catalytic mechanism, and the structure-dependent activity is attributed to a synergistic effect of surface adsorption and electron transfer processes. The POD activity enables the OLC to catalyze the decomposition of H2O2, producing reactive oxygen species for eradicating Gram-positive and Gram-negative bacteria. Additionally, toxicity tests based on nematode and mouse models confirmed the excellent biocompatibility of OLC. Furthermore, the OLC exhibited antibacterial ability and promoted bacterial-infected wound healing in a mouse model. This work not only gives a deeper understanding of the structure-activity relationship and catalytic mechanism of carbon-based nanozymes, but also unveils a novel avenue for antibacterial therapy and wound healing applications.

Fluorescent Nanocarbons: From Synthesis and Structure to Cancer Imaging and Therapy

Nanocarbons are emerging at the forefront of nanoscience, with diverse carbon nanoforms emerging over the past two decades. Early cancer diagnosis and therapy, driven by advanced chemistry techniques, play a pivotal role in mitigating mortality rates associated with cancer. Nanocarbons, with an attractive combination of well-defined architectures, biocompatibility, and nanoscale dimension, offer an incredibly versatile platform for cancer imaging and therapy. This paper aims to review the underlying principles regarding the controllable synthesis, fluorescence origins, cellular toxicity, and surface functionalization routes of several classes of nanocarbons: carbon nanodots, nanodiamonds, carbon nanoonions, and carbon nanohorns. This review also highlights recent breakthroughs regarding the green synthesis of different nanocarbons from renewable sources. It also presents a comprehensive and unified overview of the latest cancer-related applications of nanocarbons and how they can be designed to interface with biological systems and work as cancer diagnostics and therapeutic tools. The commercial status for large-scale manufacturing of nanocarbons is also presented. Finally, it proposes future research opportunities aimed at engendering modifiable and high-performance nanocarbons for emerging applications across medical industries. This work is envisioned as a cornerstone to guide interdisciplinary teams in crafting fluorescent nanocarbons with tailored attributes that can revolutionize cancer diagnostics and therapy.

Hydrogel-Based Growth Factor Delivery Platforms: Strategies and Recent Advances

Growth factors play a crucial role in regulating a broad variety of biological processes and are regarded as powerful therapeutic agents in tissue engineering and regenerative medicine in the past decades. However, their application is limited by their short half-lives and potential side effects in physiological environments. Hydrogels are identified as having the promising potential to prolong the half-lives of growth factors and mitigate their adverse effects by restricting them within the matrix to reduce their rapid proteolysis, burst release, and unwanted diffusion. This review discusses recent progress in the development of growth factor-containing hydrogels for various biomedical applications, including wound healing, brain tissue repair, cartilage and bone regeneration, and spinal cord injury repair. In addition, the review introduces strategies for optimizing growth factor release including affinity-based delivery, carrier-assisted delivery, stimuli-responsive delivery, spatial structure-based delivery, and cellular system-based delivery. Finally, the review presents current limitations and future research directions for growth factor-delivering hydrogels.

Functional PDMS Elastomers: Bulk Composites, Surface Engineering, and Precision Fabrication

Polydimethylsiloxane (PDMS)-the simplest and most common silicone compound-exemplifies the central characteristics of its class and has attracted tremendous research attention. The development of PDMS-based materials is a vivid reflection of the modern industry. In recent years, PDMS has stood out as the material of choice for various emerging technologies. The rapid improvement in bulk modification strategies and multifunctional surfaces has enabled a whole new generation of PDMS-based materials and devices, facilitating, and even transforming enormous applications, including flexible electronics, superwetting surfaces, soft actuators, wearable and implantable sensors, biomedicals, and autonomous robotics. This paper reviews the latest advances in the field of PDMS-based functional materials, with a focus on the added functionality and their use as programmable materials for smart devices. Recent breakthroughs regarding instant crosslinking and additive manufacturing are featured, and exciting opportunities for future research are highlighted. This review provides a quick entrance to this rapidly evolving field and will help guide the rational design of next-generation soft materials and devices.

Hybrid Polypyrrole and Polydopamine Nanosheets for Precise Raman/Photoacoustic Imaging and Photothermal Therapy

The development of near-infrared light responsive conductive polymers provides a useful theranostic platform for malignant tumors by maximizing spatial resolution with deep tissue penetration for diagnosis and photothermal therapy. Herein, the self-assembly of ultrathin 2D polypyrrole nanosheets utilizing dopamine as a capping agent and a monolayer of octadecylamine as a template is demonstrated. The 2D polypyrrole-polydopamine nanostructure has tunable size distribution which shows strong absorption in the first and second near-infrared windows, enabling photoacoustic imaging and photothermal therapy. The hybrid double-layer is demonstrated to increase Raman intensity for 3D Raman imaging (up to two orders of magnitude enhancement and spatial resolution up to 1 µm). The acidic environment drives reversible doping of polypyrrole, which can be detected by Raman spectroscopy. The combined properties of the nanosheets can substantially enhance performance in dual-mode Raman and photoacoustic guided photothermal therapy, as shown by the 69% light to heat conversion efficiency and higher cytotoxicity against cancer spheroids. These pH-responsive features highlight the potential of 2D conductive polymers for applications in accurate, highly efficient theranostics.

Zero-Dimensional Carbon Nanomaterials for Fluorescent Sensing and Imaging

Advances in nanotechnology and nanomaterials have attracted considerable interest and play key roles in scientific innovations in diverse fields. In particular, increased attention has been focused on carbon-based nanomaterials exhibiting diverse extended structures and unique properties. Among these materials, zero-dimensional structures, including fullerenes, carbon nano-onions, carbon nanodiamonds, and carbon dots, possess excellent bioaffinities and superior fluorescence properties that make these structures suitable for application to environmental and biological sensing, imaging, and therapeutics. This review provides a systematic overview of the classification and structural properties, design principles and preparation methods, and optical properties and sensing applications of zero-dimensional carbon nanomaterials. Recent interesting breakthroughs in the sensitive and selective sensing and imaging of heavy metal pollutants, hazardous substances, and bioactive molecules as well as applications in information encryption, super-resolution and photoacoustic imaging, and phototherapy and nanomedicine delivery are the main focus of this review. Finally, future challenges and prospects of these materials are highlighted and envisaged. This review presents a comprehensive basis and directions for designing, developing, and applying fascinating fluorescent sensors fabricated based on zero-dimensional carbon nanomaterials for specific requirements in numerous research fields.

CeO2@CuS@PDA-FA as targeted near-infrared PTT/CDT therapeutic agents for cancer cells

Single tumor treatment method usually has some defects, which makes it difficult to achieve good therapeutic effect. The ingenious combination of multiple tumor treatment methods on a single nanoplatform to achieve multifunctional treatment can effectively improve the efficiency of treatment. The targeted modification of nanomaterials can augment the precision of nanotherapeutic drugs in tumor treatment. Herein, a multifunctional nanoplatform (CeO2@CuS@PDA-FA) based on cerium dioxide nanoparticles engineered with copper sulfide (CeO2@CuS) has been constructed for synergistic photothermal therapy (PTT) and chemodynamic therapy (CDT). The CeO2@CuS were coated using polydopamine (PDA), and the modification of PDA surface by folic acid, in order to achieve the targeted effect for tumors. The localized hyperthermia induced by PTT can further improve the CDT efficiency of the nanoplatform, leading to a PTT/CDT synergistic effect. The nanoplatform possessed the capability of cancer cell-targeted and achieved better therapeutic efficacyin vitro. This work provided a new strategy for combined multifunctional theranostic platform and shows strong potential in practical applications.

Enhanced Intracellular Delivery and Cell Harvest Using a Candle Soot-Based Photothermal Platform with Dual-Stimulus Responsiveness

Intracellular delivery of bioactive macromolecules and functional materials plays a crucial role in fundamental biological research and clinical applications. Nondestructive and efficient harvesting of engineered cells is also required for some specific applications. In this work, we develop a multifunctional platform based on candle soot modified with copolymer brushes containing temperature-responsive poly(N-isopropylacrylamide) (PNIPAAm) and sugar-responsive phenylboronic acid (PBA) components. This platform possesses a high cell adhesion capacity due to the inherent hierarchical structure of candle soot and the formation of boronate ester bonds between the PBA groups and glycoproteins on the cell membrane. Under the irradiation of a near-infrared laser, the excellent light-to-heat conversion ability of candle soot enables the highly efficient delivery of macromolecules into diverse cells (including hard-to-transfect cells) attached to the surface via a photothermal-poration mechanism. Owing to the temperature-responsive properties of PNIPAAm and the sugar-responsive properties of PBA, the engineered cells could be harvested nondestructively from the platform by a mild treatment using a cold fructose solution. A proof-of-concept experiment demonstrates that fibroblasts attached to the surface could be transfected by a functional plasmid encoding basic fibroblast growth factor and then harvested efficiently and recultured with improved proliferation and migration ability. The whole delivery-harvesting process required less than 1 h, allowing the cells to be engineered without compromising their viability. This platform thus provides a widely applicable method for both the intracellular delivery of diverse macromolecules efficiently as well as harvesting engineered cells simply and safely, holding great potential for biomedical applications.

Multifunctional coatings based on candle soot with photothermal bactericidal property and desired biofunctionality

Functional coatings with desired bioactivities are required for various biomedical applications. Candle soot (CS) composed of carbon nanoparticles has attracted significant attention as a versatile component of functional coatings because of its unique physical and structural characteristics. However, the application of CS-based coatings in the biomedical field is still limited due to the lack of modification methods that can endow them with specific biofunctionality. Herein, a facile and widely applicable approach to fabricate multifunctional CS-based coatings is developed by grafting functional polymer brushes on the silica-stabilized CS. The resulting coatings not only exhibited excellent near-infrared-activated biocidal ability (the killing efficiency was over 99.99 %) due to the inherent photothermal property of CS but also showed desired biofunctions (such as antifouling property or controllable bioadhesion; the repelling efficiency and bacterial release ratio were nearly 90 %) originated from the grafted polymers. Moreover, these biofunctions were enhanced by the nanoscale structure of CS. Because the deposition of CS is a simple substrate-independent process while the grafting of polymer brushes via surface-initiated polymerization is applicable to a wide range of vinyl monomers, the proposed approach can be potentially used for the fabrication of multifunctional coatings and would extend the applications of CS in the biomedical field.

Bimetallic Hyaluronate-Modified Au@Pt Nanoparticles for Noninvasive Photoacoustic Imaging and Photothermal Therapy of Skin Cancer

Although spherical gold (Au) nanoparticles have remarkable photothermal conversion efficiency and photostability, their weak absorption in the near-infrared (NIR) region and poor penetration into deep tissues have limited further applications to NIR light-mediated photoacoustic (PA) imaging and noninvasive photothermal cancer therapy. Here, we developed bimetallic hyaluronate-modified Au-platinum (HA-Au@Pt) nanoparticles for noninvasive cancer theranostics by NIR light-mediated PA imaging and photothermal therapy (PTT). The growth of Pt nanodots on the surface of spherical Au nanoparticles enhanced the absorbance in the NIR region and broadened the absorption bandwidth of HA-Au@Pt nanoparticles by the surface plasmon resonance (SPR) coupling effect. In addition, HA facilitated the transdermal delivery of HA-Au@Pt nanoparticles through the skin barrier and enabled clear tumor-targeted PA imaging. Compared to conventional PTT via injection, HA-Au@Pt nanoparticles were noninvasively delivered into deep tumor tissues and completely ablated the targeted tumor tissues by NIR light irradiation. Taken together, we could confirm the feasibility of HA-Au@Pt nanoparticles as a NIR light-mediated biophotonic agent for noninvasive skin cancer theranostics.

Hierarchy of hybrid materials. Part-II: The place of organics-on-inorganics in it, their composition and applications

Hybrid materials or hybrids incorporating organic and inorganic constituents are emerging as a very potent and promising class of materials due to the diverse but complementary nature of their properties. This complementarity leads to a perfect synergy of properties of the desired materials and products as well as to an extensive range of their application areas. Recently, we have overviewed and classified hybrid materials describing inorganics-in-organics in Part-I (Saveleva, et al., Front. Chem., 2019, 7, 179). Here, we extend that work in Part-II describing organics-on-inorganics, i.e., inorganic materials modified by organic moieties, their structure and functionalities. Inorganic constituents comprise of colloids/nanoparticles and flat surfaces/matrices comprise of metallic (noble metal, metal oxide, metal-organic framework, magnetic nanoparticles, alloy) and non-metallic (minerals, clays, carbons, and ceramics) materials; while organic additives can include molecules (polymers, fluorescence dyes, surfactants), biomolecules (proteins, carbohydtrates, antibodies and nucleic acids) and even higher-level organisms such as cells, bacteria, and microorganisms. Similarly to what was described in Part-I, we look at similar and dissimilar properties of organic-inorganic materials summarizing those bringing complementarity and composition. A broad range of applications of these hybrid materials is also presented whose development is spurred by engaging different scientific research communities.

Research Progress of Nanomedicine-Based Mild Photothermal Therapy in Tumor

With the booming development of nanomedicine, mild photothermal therapy (mPTT, 42-45°C) has exhibited promising potential in tumor therapy. Compared with traditional PTT (>50°C), mPTT has less side effects and better biological effects conducive to tumor treatment, such as loosening the dense structure in tumor tissues, enhancing blood perfusion, and improving the immunosuppressive microenvironment. However, such a relatively low temperature cannot allow mPTT to completely eradicate tumors, and therefore, substantial efforts have been conducted to optimize the application of mPTT in tumor therapy. This review extensively summarizes the latest advances of mPTT, including two sections: (1) taking mPTT as a leading role to maximize its effect by blocking the cell defense mechanisms, and (2) regarding mPTT as a supporting role to assist other therapies to achieve synergistic antitumor curative effect. Meanwhile, the special characteristics and imaging capabilities of nanoplatforms applied in various therapies are discussed. At last, this paper puts forward the bottlenecks and challenges in the current research path of mPTT, and possible solutions and research directions in future are proposed correspondingly.

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.

Carbon nanomaterials for drug delivery and tissue engineering

Carbon nanomaterials are some of the state-of-the-art materials used in drug-delivery and tissue-engineering research. Compared with traditional materials, carbon nanomaterials have the advantages of large specific surface areas and unique properties and are more suitable for use in drug delivery and tissue engineering after modification. Their characteristics, such as high drug loading and tissue loading, good biocompatibility, good targeting and long duration of action, indicate their great development potential for biomedical applications. In this paper, the synthesis and application of carbon dots (CDs), carbon nanotubes (CNTs) and graphene in drug delivery and tissue engineering are reviewed in detail. In this review, we discuss the current research focus and existing problems of carbon nanomaterials in order to provide a reference for the safe and effective application of carbon nanomaterials in drug delivery and tissue engineering.

Squaramide-Immobilized Carbon Nanoparticles for Rapid and High-Efficiency Elimination of Anthropogenic Mercury Ions from Aquatic Systems

Water pollution due to environmental remediation and poor waste administration in certain areas of the globe signifies a serious problem in acquiring safe and clean drinking water. This problem is especially critical in rural areas, where advanced water purification techniques are deficient, and it remains a daunting task for ecosystem and public health protection. This critical task can be addressed herein by developing scalable poly squaramide-phenyl methacrylamide (PSQ)-functionalized carbon nanoparticles (CNPs) (PSQ-CNPs) with densely populated chelating sites with strong Hg²⁺-binding capacity. The PSQ-CNPs have shown high efficiency in removing Hg²⁺ from aqueous solution, providing a Hg²⁺ capacity of 2840 mg g^-1, surpassing all the amine and thiol-based adsorbents reported hitherto. More significantly, the adsorbent reveals the largest distribution coefficient value (K_d) of 9.09 × 10¹⁰ mL g^-1, which allows it to reduce Hg²⁺ content from 10 ppm to less than 0.011 ppb, well below the United States Environmental Protection Agency (EPA) limits for drinking water standards (2 ppb). The adsorption measurements of the adsorbent followed the Langmuir isotherm model and pseudo-second order. The practical applicability of PSQ-CNPs was verified with the real samples (the lake, river, and industrial wastewater) and has been proven to be excellent. The adsorbent could still retain its Hg²⁺ removal efficacy even after 12 sorption cycles. It is attributed that the remarkable performance of PSQ-CNPs arises from the high-density chelating sites and pores on the surface of CNPs. The present work shows a new benchmark for Hg²⁺-removal adsorbents and presents a novel practical approach for decontaminating Hg²⁺ and other heavy metal ions from wastewater.

On-Demand Maneuvering of Diverse Prodrug Liquids on a Light-Responsive Candle-Soot-Hybridized Lubricant-Infused Slippery Surface for Highly Effective Toxicity Screening

At present, microscale high-throughput screening (HTS) for drug toxicity has drawn increased attention. Reported methods are often constrained by the inability to execute rapid fusion over diverse droplets or the inflexibility of relying on rigid customized templates. Herein, a light-responsive candle-soot-hybridized lubricant-infused slippery surface (CS-LISS) was reported by one-step femtosecond laser cross-scanning to realize highly effective and flexible drug HTS. Due to its low-hysteresis merits, the CS-LISS can readily steer diverse droplets toward arbitrary directions at a velocity over 1.0 mm/s with the help of tracing lateral near-infrared irradiation; additionally, it has the capability of self-cleaning and self-deicing. Significantly, by integrating the CS-LISS with a GFP HeLa cell chip, high-efficiency drug toxicity screening can be successfully achieved with the aid of fluorescence imaging. This work provides insights into the design of microscale high-throughput drug screening.

Carbon Graphitization: Towards Greener Alternatives to Develop Nanomaterials for Targeted Drug Delivery

Carbon nanomaterials have attracted great interest for their unique physico-chemical properties for various applications, including medicine and, in particular, drug delivery, to solve the most challenging unmet clinical needs. Graphitization is a process that has become very popular for their production or modification. However, traditional conditions are energy-demanding; thus, recent efforts have been devoted to the development of greener routes that require lower temperatures or that use waste or byproducts as a carbon source in order to be more sustainable. In this concise review, we analyze the progress made in the last five years in this area, as well as in their development as drug delivery agents, focusing on active targeting, and conclude with a perspective on the future of the field.

Gold nanomaterials for oral cancer diagnosis and therapy: Advances, challenges, and prospects

Early diagnosis and treatment of oral cancer are vital for patient survival. Since the oral cavity accommodates the second largest and most diverse microbiome community after the gut, the diagnostic and therapeutic approaches with low invasiveness and minimal damage to surrounding tissues are keys to preventing clinical intervention-related infections. Gold nanoparticles (AuNPs) are widely used in the research of cancer diagnosis and therapy due to their excellent properties such as surface-enhanced Raman spectroscopy, surface plasma resonance, controlled synthesis, the plasticity of surface morphology, biological safety, and stability. AuNPs had been used in oral cancer detection reagents, tumor-targeted therapy, photothermal therapy, photodynamic therapy, and other combination therapies for oral cancer. AuNPs-based noninvasive diagnosis and precise treatments further reduce the clinical intervention-related infections. This review is focused on the recent advances in research and application of AuNPs for early screening, diagnostic typing, drug delivery, photothermal therapy, radiotherapy sensitivity treatment, and combination therapy of oral cancer. Distinctive reports from the literature are summarized to highlight the latest advances in the development and application of AuNPs in oral cancer diagnosis and therapy. Finally, this review points out the challenges and prospects of possible applications of AuNPs in oral cancer diagnosis and therapy.

Template-Free Synthesis of Porous Fluorescent Carbon Nanomaterials with Gluten for Intracellular Imaging and Drug Delivery

A series of carbon nanomaterials, including carbon dots, carbon nanorings (CNRs), and porous carbon nanoballs, were facilely prepared by a template-free hydrothermal treatment of gluten as the sole carbon source. Driven by the hydrophobicity interaction, a concentration-dependent self-assembly of gluten was observed in an aqueous solution, leading to the subsequent formation of different morphologies of carbon nanomaterials in a hydrothermal treatment. Among these carbon nanomaterials, the CNRs exhibit bright photoluminescence with a quantum yield of 47.0%. Furthermore, CNRs also have a large surface area and low toxicity, making them an excellent drug carrier for chemotherapeutics. A model drug molecule doxorubicin (DOX) was successfully loaded on the CNRs, and the CNRs-DOX complexes exhibit a pH-dependent DOX release behavior. Compared with free DOX, the CNRs-DOX complexes can induce a higher level of apoptosis and lower level of necrosis, showing promise as anticancer agents.

Rose Bengal-Derived Ultrabright Sulfur-Doped Carbon Dots for Fast Discrimination between Live and Dead Cells

The discrimination between dead and live cells is crucial for cell viability evaluation. Carbon dots (CDs), with advantages like simple and cost-effective synthesis, excellent biocompatibility, and high photostability, have shown potential for realizing selective live/dead cell staining. However, most of the developed CDs with the live/dead cell discrimination capacity usually have low photoluminescence quantum yields (PLQYs) and excitation wavelength-dependent fluorescence emission (which can cause fluorescence overlap with other fluorescent probes and make dual-color live/dead staining impossible), and hence, developing ultrabright CDs with excitation wavelength-independent fluorescence emission property for live/dead cell discrimination becomes an important task. Here, using a one-pot hydrothermal method, we prepared ultrasmall (∼1.6 nm), ultrabright (PLQY: ∼78%), and excitation wavelength-independent sulfur-doped carbon dots (termed S-CDs) using rose bengal and 1,4-dimercaptobenzene as raw materials and demonstrated that the S-CDs could rapidly (∼5 min) and accurately distinguish dead cells from live ones for almost all the cell types including bacterial, fungal, and animal cells in a wash-free manner. We confirmed that the S-CDs could rapidly pass through the dead cell surfaces to enter the interior of the dead cells, thus visualizing these dead cells. In contrast, the S-CDs could not enter the interior of live cells and thus could not stain these live cells. We further verified that the S-CDs presented better biocompatibility and higher photostability than the commercial live/dead staining dye propidium iodide, ensuring its bright application prospect in cell imaging and cell viability assessment. Overall, this work develops a type of CDs capable of realizing the live/dead cell discrimination of almost all the cell types (bacterial, fungal, and animal cells), which has seldom been achieved by other fluorescent nanoprobes.

Emerging Single-Atom Catalysts/Nanozymes for Catalytic Biomedical Applications

Single-atom catalysts (SACs) are a type of atomically dispersed nanozymes with the highest atom utilization, which employ low-coordinated single atoms as the catalytically active sites. SACs not only inherit the merits of traditional nanozymes, but also hold high catalytic activity and superb catalytic selectivity, which ensure their tremendous application potential in environmental remediation, energy storage and conversion, chemical industry, nanomedicine, etc. Nevertheless, undesired aggregation effect of single atoms during preactivation and reaction processes is significantly enhanced owing to the high surface free energy of single atoms. In this case, appropriate substrates are requisite to prevent the aggregation event through the powerful interactions between the single atoms and the substrates, thereby stabilizing the high catalytic activity of the catalysts. In this review, the synthetic methods and characterization approaches of SACs are first described. Then the application cases of SACs in nanomedicine are summarized. Finally, the current challenges and future opportunities of the SACs in nanomedicine are outlined. It is hoped that this review may have implications for furthering the development of new SACs with improved biophysicochemical properties and broadened biomedical applications.

Biomineralized Prussian Blue Nanotherapeutic for Enhanced Cancer Photothermal Therapy

Photothermal therapy is a promising tumor ablation technique that converts light into heat energy to kill cancer cells. Prussian blue (PB), a biocompatible photothermal reagent, has been widely explored for...

Carbon nanomaterials as emerging nanotherapeutic platforms to tackle the rising tide of cancer - A review

Cancer has become one of the main reasons for human death in recent years. Around 18 million new cancer cases and approximately 9.6 million deaths from cancer reported in 2018, and the annual number of cancer cases will have increased to 22 million in the next two decades. These alarming facts have rekindled researchers' attention to develop and apply different approaches for cancer therapy. Unfortunately, most of the applied methods for cancer therapy not only have adverse side effects like toxicity and damage of healthy cells but also have a short lifetime. To this end, introducing innovative and effective methods for cancer therapy is vital and necessary. Among different potential materials, carbon nanomaterials can cope with the rising threats of cancer. Due to unique physicochemical properties of different carbon nanomaterials including carbon, fullerene, carbon dots, graphite, single-walled carbon nanotube and multi-walled carbon nanotubes, they exhibit possibilities to address the drawbacks for cancer therapy. Carbon nanomaterials are prodigious materials due to their ability in drug delivery or remedial of small molecules. Functionalization of carbon nanomaterials can improve the cancer therapy process and decrement the side effects. These exceptional traits make carbon nanomaterials as versatile and prevalent materials for application in cancer therapy. This article spotlights the recent findings in cancer therapy using carbon nanomaterials (2015-till now). Different types of carbon nanomaterials and their utilization in cancer therapy were highlighted. The plausible mechanisms for the action of carbon nanomaterials in cancer therapy were elucidated and the advantages and disadvantages of each material were also illustrated. Finally, the current problems and future challenges for cancer therapy based on carbon nanomaterials were discussed.

Mesoporous onion-like carbon nanostructures from natural oil for high-performance supercapacitor and electrochemical sensing applications: Insights into the post-synthesis sonochemical treatment on the electrochemical performance

Although onion-like carbon nanostructures (OLCs) are attractive materials for energy storage, their commercialization is hampered by the absence of a simple, cost-effective, large-scale synthesis route and binder-free electrode processing. The present study employs a scalable and straightforward technique to fabricate sonochemically tailored OLCs-based high-performance supercapacitor electrode material. An enhanced supercapacitive performance was demonstrated by the OLCs when sonicated in DMF at 60 °C for 15 min, with a specific capacitance of 647 F/g, capacitance retention of 97% for 5000 cycles, and a charge transfer resistance of 3 Ω. Furthermore, the OLCs were employed in the electrochemical quantification of methylene blue, a potential COVID-19 drug. The sensor demonstrated excellent analytical characteristics, including a linear range of 100 pM to 1000 pM, an ultralow sensitivity of 64.23 pM, and a high selectivity. When used to identify and quantify methylene blue in its pharmaceutical formulation, the sensor demonstrated excellent reproducibility, high stability, and satisfactory recovery.

Recent Progress on NIR-II Photothermal Therapy

Photothermal therapy is a very promising treatment method in the field of cancer therapy. The photothermal nanomaterials in near-infrared region (NIR-I, 750-900 nm) attracts extensive attention in recent years because of the good biological penetration of NIR light. However, the penetration depth is still not enough for solid tumors due to high tissue scattering. The light in the second near-infrared region (NIR-II, 1000-1700 nm) allows deeper tissue penetration, higher upper limit of radiation and greater tissue tolerance than that in the NIR-I, and it shows greater application potential in photothermal conversion. This review summarizes the photothermal properties of Au nanomaterials, two-dimensional materials, metal oxide sulfides and polymers in the NIR-II and their application prospects in photothermal therapy. It will arouse the interest of scientists in the field of cancer treatment as well as nanomedicine.

Polyphenol-Containing Nanoparticles: Synthesis, Properties, and Therapeutic Delivery

Polyphenols, the phenolic hydroxyl group-containing organic molecules, are widely found in natural plants and have shown beneficial effects on human health. Recently, polyphenol-containing nanoparticles have attracted extensive research attention due to their antioxidation property, anticancer activity, and universal adherent affinity, and thus have shown great promise in the preparation, stabilization, and modification of multifunctional nanoassemblies for bioimaging, therapeutic delivery, and other biomedical applications. Additionally, the metal-polyphenol networks, formed by the coordination interactions between polyphenols and metal ions, have been used to prepare an important class of polyphenol-containing nanoparticles for surface modification, bioimaging, drug delivery, and disease treatments. By focusing on the interactions between polyphenols and different materials (e.g., metal ions, inorganic materials, polymers, proteins, and nucleic acids), a comprehensive review on the synthesis and properties of the polyphenol-containing nanoparticles is provided. Moreover, the remarkable versatility of polyphenol-containing nanoparticles in different biomedical applications, including biodetection, multimodal bioimaging, protein and gene delivery, bone repair, antibiosis, and cancer theranostics is also demonstrated. Finally, the challenges faced by future research regarding the polyphenol-containing nanoparticles are discussed.

Application of carbon nano onions in the biomedical field: recent advances and challenges

Carbon nano onions (CNOs) are carbonaceous nanostructures composed of multiple concentric shells of fullerenes. These cage-within-cage structures remain as one of the most exciting and fascinating carbon forms, along with graphene and its derivatives, due to their unique chemical and physical properties. Their exceptional biocompatibility and biosafety make them an attractive choice in a wide range of areas, including biological systems. This nanomaterial displays low toxicity, high dispersity in aqueous solutions (upon surface functionalization), and high pharmaceutical efficiency. Even though CNOs were discovered almost simultaneously along with carbon nanotubes (CNTs), their potential in biomedical applications still appears unrealized. The existence of CNOs is equally important, just like any other carbon nanostructures such as CNTs and fullerenes, because they display the ability of carbon to form another unique nanostructure with wonderful properties. Therefore, this mini-review summarizes recent studies geared towards developing CNOs for various biomedical applications, including sensing, drug delivery, imaging, tissue engineering, and as a therapeutic drug. It concludes by discussing other potential applications of this unique nanomaterial.

Low-Temperature Photothermal Therapy: Strategies and Applications

Although photothermal therapy (PTT) with the assistance of nanotechnology has been considered as an indispensable strategy in the biomedical field, it still encounters some severe problems that need to be solved. Excessive heat can induce treated cells to develop thermal resistance, and thus, the efficacy of PTT may be dramatically decreased. In the meantime, the uncontrollable diffusion of heat can pose a threat to the surrounding healthy tissues. Recently, low-temperature PTT (also known as mild PTT or mild-temperature PTT) has demonstrated its remarkable capacity of conquering these obstacles and has shown excellent performance in bacterial elimination, wound healing, and cancer treatments. Herein, we summarize the recently proposed strategies for achieving low-temperature PTT based on nanomaterials and introduce the synthesis, characteristics, and applications of these nanoplatforms. Additionally, the combination of PTT and other therapeutic modalities for defeating cancers and the synergistic cancer therapeutic effect of the combined treatments are discussed. Finally, the current limitations and future directions are proposed for inspiring more researchers to make contributions to promoting low-temperature PTT toward more successful preclinical and clinical disease treatments.

Nanomedicines for combating multidrug resistance of cancer

Chemotherapy typically involves the use of specific chemodrugs to inhibit the proliferation of cancer cells, but the frequent emergence of a variety of multidrug-resistant cancer cells poses a tremendous threat to our combat against cancer. The fundamental causes of multidrug resistance (MDR) have been studied for decades, and can be generally classified into two types: one is associated with the activation of diverse drug efflux pumps, which are responsible for translocating intracellular drug molecules out of the cells; the other is linked with some non-efflux pump-related mechanisms, such as antiapoptotic defense, enhanced DNA repair ability, and powerful antioxidant systems. To overcome MDR, intense efforts have been made to develop synergistic therapeutic strategies by introducing MDR inhibitors or combining chemotherapy with other therapeutic modalities, such as phototherapy, gene therapy, and gas therapy, in the hope that the drug-resistant cells can be sensitized toward chemotherapeutics. In particular, nanotechnology-based drug delivery platforms have shown the potential to integrate multiple therapeutic agents into one system. In this review, the focus was on the recent development of nanostrategies aiming to enhance the efficiency of chemotherapy and overcome the MDR of cancer in a synergistic manner. Different combinatorial strategies are introduced in detail and the advantages as well as underlying mechanisms of why these strategies can counteract MDR are discussed. This review is expected to shed new light on the design of advanced nanomedicines from the angle of materials and to deepen our understanding of MDR for the development of more effective anticancer strategies. This article is categorized under: Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Continuous Roll-to-Roll Production of Carbon Nanoparticles from Candle Soot

Carbon nanoparticles (CNPs) have been considered as essential components for various applications including sensors, quantum dots, electrocatalysts, energy storages, lubrication, and functional coatings. Uniform and functional CNP materials can be obtained from candle soot. However, the production of CNPs from candle soot is not a continuous process, limiting the practical production and applications of such materials. Here, a rotating-deposition and separation system for high-efficiency production of low-cost and high-quality CNPs from candle soot is presented. The characteristic of CNPs can be controlled by adjusting the system parameters. Moreover, obtained CNPs can act as photothermal superhydrophobic anti-icing coatings on various substrates. With a sliding angle of less than 3°, water drops can keep rolling off without further nucleation of ice. The reported preparing method is suitable for large-scale applications and various kinds of surfaces and shows great potentials in the growing demands of anti-icing.

Carbon nano-onions as potential nanocarriers for drug delivery

Nanocarriers are nano-sized delivery vesicles that can transport desired molecules to a specific location. The utilisation of nanocarriers for targeted drug-delivery is an emerging field that aims to solve certain disadvantages of free drug delivery; including premature drug degradation, non-specific toxicity, lack of tissue penetration, undesired side-effects, and multi-drug resistance. The nanocarrier approach has proven effective in this regard, with some examples of FDA approved nanocarrier systems available on the market. In this perspective, we investigate the potential of carbon nano-onions (CNOs) as nanocarriers for drug delivery. The various criteria and considerations for designing a nanocarrier are outlined, and we thoroughly discuss how CNOs fit these criteria. Given the rapidly developing interest in CNOs, this perspective provides a baseline discussion for the use of this novel carbon nanomaterial as a potential nanocarrier for drug delivery.

Soft-chemistry synthesis, solubility and interlayer spacing of carbon nano-onions

Carbon nano-onions (CNOs), as one of the allotropes of carbon, have attracted great attention because of their excellent performance in many fields, especially in capacitors. Developing soft-chemistry synthesis methods is critically of importance, while the forming mechanism in this area is not clear. In this paper, we present a critical review of CNOs regarding the structure, especially interlayer spacing, and synthesis processes, elaborating the recent progress on soft-chemistry methods. Hansen solubility parameter theory is applied to predict and regulate the solubility of CNOs. This article would be inspirational and give new insights into understanding the formation and properties of CNOs.

Fluorescent Carbon Nano-onion as Bioimaging Probe

Concentrically arranged multilayered fullerenes exhibiting onion-like morphology are popularly known as carbon nano-onion (CNO) and are useful in bioimaging application. On the basis of the origin of the fluorescence, the CNO-based nanoprobes are classified into type I and type II. The type I CNO-based nanoprobe needs a secondary moiety such as organic dyes or an amine functionalization at its surface to induce the fluorescence. On the other hand, the emission in type II does not originate from such an external surface passivating agent. The CNO-based system not only shows structural similarity to the well-known multiwalled carbon nanotube but is also a bit more advantageous because of its low cytotoxicity. These features enable their prolonged use in the biological system for imaging purposes. In particular, we have covered the aspects of synthesis, surface functionalization, the origin of fluorescence, and biocompatibility. In addition, recent developments directed toward in vitro and in vivo imaging studies by utilizing CNO-based nanoprobes are summarized here.

Internalized Carbon Dots for Enhanced Extracellular Electron Transfer in the Dark and Light

Cellular internalization of nanomaterials to endow cells with more functionalities is highly desirable. Herein, a straightforward strategy for internalizing red-emission carbon dots (CDs) into Shewanella xiamenensis is proposed. This suggests that the internalized CDs not only afford enhanced conductivity of bacteria but also trigger the cellular physiological response to secrete abundant electron shuttles to aid the boosting of extracellular electron transfer (EET) efficiency. Additionally, once illuminated, internalized CDs can also serve as light absorbers to allow for photogenerated electrons to be transferred into cellular metabolism to further facilitate light-enhanced EET processes. Specifically, the findings advance the fundamental understanding of the interaction between internalized carbon-based semiconductor and cells in the dark and light, and provide a facile and effective strategy for enhancing EET efficiency.

A tumor-targeted theranostic nanomedicine with strong absorption in the NIR-II biowindow for image-guided multi-gradient therapy

Developing new strategies to enhance drug accumulation in the tumor and therapeutic efficacy is of great importance in the field of tumor therapy. Herein, a peanut-like multifunctional nanomedicine (CuS-PGH NMs) made of CuS nanoparticles encapsulated in poly(l-lysine)(PLL)/glucose oxidase (GOx)-hyaluronic acid (HA) shells has been constructed via layer-by-layer (LbL) assembly, and shows good biocompatibility and effective multi-gradient therapy. Because of the enhanced permeability and retention (EPR) effect, the CuS-PGH NMs could significantly enhance the cellular uptake by tumors overexpressing CD44 receptors, which respond to hyaluronidase (HAase)-triggered surface charge conversion. Once internalized by the tumor, GOx was the first to be exposed and could effectively deplete endogenous glucose for starvation therapy, and the excess H2O2 was then converted into highly toxic hydroxyl radicals (˙OH) via a Cu+-mediated Fenton-like reaction for chemodynamic therapy (CDT). Meanwhile, the as-obtained Cu+ ions accompanied the regenerated less-active Cu2+ ions. Interestingly, the high content of H2O2 could, in turn, accelerate Cu2+/Cu+ conversion to promote the Cu+-H2O2 reaction for enhanced chemodynamic therapy (CDT), thereby achieving efficient tumor growth suppression via synergistic starvation/CDT therapy. Subsequently, owing to the strong NIR-II absorption capability of CuS-PGH NMs, effective photothermal tumor ablation of the weakened tumor cells could be realized with the precise guidance of NIR-II PAI. This multi-gradient therapeutic strategy has been demonstrated to have excellent antitumor activity with minimal nonspecific damages, and offers a new avenue to precise tumor therapy.

Targeted Engineering of Medicinal Chemistry for Cancer Therapy: Recent Advances and Perspectives

Severe side effects and poor therapeutic efficacy are the main drawbacks of current anticancer drugs. These problems can be mitigated by targeting, but the targeting efficacy of current drugs is poor and urgently needs improvement. Taking this into consideration, this Review first summarizes the current targeting strategies for cancer therapy in terms of cancer tissue and organelles. Then, we analyse the systematic targeting of anticancer drugs and conclude that a typical journey for a targeted drug administered by intravenous injection is a CTIO cascade of at least four steps. Furthermore, to ensure high overall targeting efficacy, the properties of a targeting drug needed in each step are further analysed, and some guidelines for structure optimization to obtain effective targeting drugs are offered. Finally, some viewpoints highlighting the crucial problems and potential challenges of future research on targeted cancer therapy are presented. This review could actively promote the development of precision medicine against cancer.

Sensitive detection of Sudan dyes using tire-derived carbon dots as a fluorescent sensor

In this paper, we exploit an innovative strategy to reuse waste rubber tires as a low-cost source for the fabrication of a high-value material, fluorescent carbon dots (CDs). In the hydrothermal condition, ammonium persulphate is utilized to oxidize the tires and offer nitrogen atom for doping, to produce CDs with a high quantum yield (QY) of up to 23.8%. Such a QY is outstanding among the reported waste-derived CDs. It is found that the fluorescence of CDs can be remarkably quenched by Sudan I-IV with negligible interference from other substances. The corresponding linear ranges are 0.5-60, 0.5-60, 1-70, and 1-70 μM, and limits of detection are 0.17, 0.21, 0.53, and 0.62 μM for Sudan I, II, III, and IV, respectively. Systematic investigations reveal that the fluorescence quenching mainly stems from the inner filter effect. Moreover, the CD-based sensor shows an excellent applicability for the assay of Sudan dyes in chili powder sample.

Engineering Gadolinium-Integrated Tellurium Nanorods for Theory-Oriented Photonic Hyperthermia in the NIR-II Biowindow

Near-infrared (NIR) light-triggered hyperthermia has exhibited promising prospects in oncology therapy due to the unique merits including minimal invasiveness, monitorable, excellent therapeutic effect, and negligible side effects. Especially, the second NIR biowindow (NIR-II, 1000-1700 nm) with less absorbance and scattering by skin tissue, and deep tissue penetration, has received extensive attention for photonic hyperthermia. Unfortunately, the dissatisfactory photothermal conversion efficiency (PCE) and cumbersome preparation process of photo-driven heat conversion nanomaterials seriously hamper the future clinical application. To combat the aforementioned challenges, high imaging performance and desired therapeutic outcome 1D nanorods are constructed based on gadolinium-integrated tellurium nanorods (Te-Gd). In this system, magnetic resonance (MR) imaging and X-ray computed tomography (CT) imaging-guided photonic hyperthermia can be easily implemented in cooperation with Te-Gd. Importantly, Te-Gd possesses high PCE (41%) in the NIR-II biowindow because the transition of the excited electron can easily occur from the valence band (VB) to the conduction band (CB) on (1 0 1) and (1 0 2) crystal planes. Furthermore, the distinctive photostability, high tumor accumulation, as well as low systemic adverse effects of Te-Gd guarantee the potential in the clinic.

Superhydrophobic photothermal icephobic surfaces based on candle soot

Ice accumulation causes various problems in our daily life for human society. The daunting challenges in ice prevention and removal call for novel efficient antiicing strategies. Recently, photothermal materials have gained attention for creating icephobic surfaces owing to their merits of energy conservation and environmental friendliness. However, it is always challenging to get an ideal photothermal material which is cheap, easily fabricating, and highly photothermally efficient. Here, we demonstrate a low-cost, high-efficiency superhydrophobic photothermal surface, uniquely based on inexpensive commonly seen candle soot. It consists of three components: candle soot, silica shell, and polydimethylsiloxane (PDMS) brushes. The candle soot provides hierarchical nano/microstructures and photothermal ability, the silica shell strengthens the hierarchical candle soot, and the grafted low-surface-energy PDMS brushes endow the surface with superhydrophobicity. Upon illumination under 1 sun, the surface temperature can increase by 53 °C, so that no ice can form at an environmental temperature as low as -50 °C and it can also rapidly melt the accumulated frost and ice in 300 s. The superhydrophobicity enables the melted water to slide away immediately, leaving a clean and dry surface. The surface can also self-clean, which further enhances its effectiveness by removing dust and other contaminants which absorb and scatter sunlight. In addition, after oxygen plasma treatment, the surface can restore superhydrophobicity with sunlight illumination. The presented icephobic surface shows great potential and broad impacts owing to its inexpensive component materials, simplicity, ecofriendliness, and high energy efficiency.

Amplified Photoacoustic Signal and Enhanced Photothermal Conversion of Polydopamine-Coated Gold Nanobipyramids for Phototheranostics and Synergistic Chemotherapy

Light-responsive nanoprobes were suffering from the threat of high-dose laser irradiation, and it was important for constructing new nanoprobes for safe and efficient phototheranostics. Here, polydopamine (PDA)-coated gold nanobipyramids (AuNBPs@PDA) were synthesized for amplified photoacoustic (PA) signal and enhanced photothermal conversion with low-dose laser irradiation and then doxorubicin (DOX)-loaded AuNBPs@PDA-DOX nanoprobes were constructed for PA imaging-guided synergistic photothermal therapy (PTT) and chemotherapy. The AuNBPs@PDA nanoparticles possessed higher photothermal conversion efficiency (42.07%) and stronger PA signal than those of AuNBP nanoparticles, and the AuNBPs@PDA-DOX nanoprobes showed dual-responsive DOX release of pH and photothermal stimulation. With low-dose laser irradiation (1.0 W/cm²) and low-concentration AuNBPs@PDA-DOX (60 μg/mL), the 4T1 cell viability was reduced to about 5%, owing to the combination of PTT and chemotherapy, compared with 42.3% of single chemotherapy and 25.3% of single PTT. Moreover, by modeling 4T1 tumor-bearing nude mice, in vivo PA imaging was achieved and the tumors were completely inhibited, demonstrating the excellent synergistic effect of PTT/chemotherapy. Therefore, the developed AuNBPs@PDA-DOX nanoprobes can be used for phototheranostics and synergistic chemotherapy, achieving low-dose laser irradiation and high-efficient visualized theranostics.

Prototypic Heptamethine Cyanine Incorporating Nanomaterials for Cancer Phototheragnostic

Developing technologies that allow the simultaneous diagnosis and treatment of cancer (theragnostic) has been the quest of numerous interdisciplinary research teams. In this context, nanomaterials incorporating prototypic near infrared (NIR)-light responsive heptamethine cyanines have been showing very promising results for cancer theragnostic. The precisely engineered features of these nanomaterials endow them with the ability to achieve a high tumor accumulation, enabling a tumor's visualization by NIR fluorescence and photoacoustic imaging modalities. Upon interaction with NIR light, the tumor-homed heptamethine cyanine-incorporating nanomaterials can also produce a photothermal/photodynamic effect with a high spatio-temporal resolution and minimal side effects, leading to an improved therapeutic outcome. This progress report analyses the application of nanomaterials incorporating prototypic NIR-light responsive heptamethine cyanines (IR775, IR780, IR783, IR797, IR806, IR808, IR820, IR825, IRDye 800CW, and Cypate) for cancer photothermal therapy, photodynamic therapy, and imaging. Overall, the continuous development of nanomaterials incorporating the prototypic NIR absorbing heptamethine cyanines will cement their phototheragnostic capabilities.