Nucleus-targeted carbon dots as peroxidase nanozyme for photoacoustic imaging and phototherapy of tumor

High-purity carbon dots (CDs) with a highly π-conjugated sp2-hybridized graphite structure were prepared by the pulse electrolysis method using the graphite plate as raw material. Photoacoustic signal together with photothermal effect was found in the CDs-dispersed suspensions under near-infrared (NIR) irradiation. For the suspension with the CDs concentration of 500 μg/mL, the photothermal conversion efficiency is high up 64.3% and the solution's temperature can be increased to 82.2 °C under NIR irradiation. Moreover, CDs can be effectively endocytosed by human hepatoma (HepG2) cells with a few hours, act as peroxidase nanozyme to decompose H2O2 and facilitate the production of reactive oxygen species. Under NIR irradiation, CDs exhibit an outstanding apoptosis-inducing effect on HepG2 cells by the photothermal effect. In addition, in vivo experiments show that CDs can be used in photoacoustic imaging (PAI) and guiding the tumor treatment. As a result, the nucleus-targeted CDs with an unique combination of PAI and photothermal effect have potential in cancer diagnosis and treatment.

Photothermal Performance of Lignin-Based Nanospheres and Their Applications in Water Surface Actuators

In this study, the photothermal performance of lignin-based nanospheres was investigated. Subsequently, a photothermal actuator was prepared using lignin-based carbon nanospheres (LCNSs). The results demonstrated that LCNSs exhibited an impressive photothermal conversion efficiency of up to 83.8%. This extreme efficiency significantly surpasses that of lignin nanospheres (LNSs) and covalently stabilized LNSs (HT-LNSs). As a structural material, a hydrophobic coating was effectively engineered by LCNSs on the filter paper, achieving a water contact angle of 151.9° ± 4.6°, while maintaining excellent photothermal effects (with a temperature increment from room temperature to 138 °C in 2 s). When employing hydrophobic filter paper as the substrate for the photothermaldriven actuator, under the influence of a 1.0 W/cm2 power-density NIR laser, the material exhibited outstanding photothermal actuation, achieving speeds up to 16.4 mm/s. In addition, the direction of motion of the actuator can be adjusted in accordance with the location of the NIR light irradiation. This study offers valuable perspectives on the application of LNSs for highvalue applications and the development of innovative photothermal-driven actuators.

Efficient preparation of nitrogen-doped lignin-based carbon nanotubes and the selectivity of nitrogen speciation for photothermal therapy

In this study, the lignin was pre-modified using small-molecule nitrogen-containing compounds, and then the nitrogen-doped lignin-based carbon nanotubes (L-NCNTs) were fabricated by pyrolysis using the modified lignin as raw materials. The obtained L-NCNTs were multi-walled carbon nanotubes with diameters between 10 and 80 nm. The modification of lignin had an important effect on the nitrogen morphology of L-NCNTs, and promoted the high selectivity of pyridine-N in the L-NCNTs. Defects and pyridinic-N structure were conducive to boosting photothermal properties of the L-NCNTs. The photothermal conversion efficiency of the L-NCNTs after 808 nm laser irradiation for 5 min reached 58.8 %. The L-NCNTs can be used as photothermal agents in drug delivery system to achieve mild photothermal therapy, and it is basically non-toxic to normal cells, indicating good biocompatibility. This work provides new ideas for development of lignin-based high value-added products from biomass.

Advances in Single-component inorganic nanostructures for photoacoustic imaging guided photothermal therapy

Phototheranostic based on photothermal therapy (PTT) and photoacoustic imaging (PAI), as one of avant-garde medical techniques, have sparked growing attention because it allows noninvasive, deeply penetrative, and highly selective and effective therapy. Among a variety of phototheranostic nanoagents, single-component inorganic nanostructures are found to be novel and attractive PAI and PTT combined nanotheranostic agents and received tremendous attention, which not only exhibit structural controllability, high tunability in physiochemical properties, size-dependent optical properties, high reproducibility, simple composition, easy functionalization, and simple synthesis process, but also can be endowed with multiple therapeutic and imaging functions, realizing the superior therapy result along with bringing less foreign materials into body, reducing systemic side effects and improving the bioavailability. In this review, according to their synthetic components, conventional single-component inorganic nanostructures are divided into metallic nanostructures, metal dichalcogenides, metal oxides, carbon based nanostructures, upconversion nanoparticles (UCNPs), metal organic frameworks (MOFs), MXenes, graphdiyne and other nanostructures. On the basis of this category, their detailed applications in PAI guide PTT of tumor treatment are systematically reviewed, including synthesis strategies, corresponding performances, and cancer diagnosis and therapeutic efficacy. Before these, the factors to influence on photothermal effect and the principle of in vivo PAI are briefly presented. Finally, we also comprehensively and thoroughly discussed the limitation, potential barriers, future perspectives for research and clinical translation of this single-component inorganic nanoagent in biomedical therapeutics.

Green synthesis of multifunctional carbon quantum dots: An approach in cancer theranostics

Carbon quantum dots (CQDs) have gained significant growing attention in the recent past due to their peculiar characteristics including smaller size, high surface area, photoluminescence, chemical stability, facile synthesis and functionalization possibilities. They are carbon nanostructures having less than 10 nm size with fluorescent properties. In recent years, the scientific community is curiously adopting biomass precursors for the preparation of CQDs over the chemical compounds. These biomass sources are sustainable, eco-friendly, inexpensive, widely available and convert waste into valuable materials. Hence in our work the fundamental understating of diverse fabrication methodologies of CQDs, and the types of raw materials employed in recent times, are all examined and correlated comprehensively. Their unique combination of remarkable properties, together with the ease with which they can be fabricated, makes CQDs as promising materials for applications in diverse biomedical fields, in particular for bio-imaging, targeted drug delivery and phototherapy for cancer treatment. The mechanism for luminescence is of considerable significance for leading the synthesis of CQDs with tunable fluorescence emission. Therefore, it is aimed to explore and provide an updated review on (i) the recent progress on the different synthesis methods of biomass-derived CQDs, (ii) the contribution of surface states or functional groups on the luminescence origin and (iii) its potential application for cancer theranostics, concentrating on their fluorescence properties. Finally, we explored the challenges in modification for the synthesis of CQDs from biomass derivatives and the future scope of CQDs in phototherapy for cancer theranostics.

Hollow carbon nanospheres embedded with stoichiometric γ-Fe2O3 and GdPO4: tuning the nanospheres for in vitro and in vivo size effect evaluation

The size modulation of hollow carbon nanospheres (HCSs) has attracted great interest in the contexts of cellular uptake, drug delivery and bioimaging. In this study, a facile fabrication method was specifically used to minimize all influencing factors except for the particle size. A series of nanoparticles of hollow carbon nanospheres embedded with magnetic resonance imaging (MRI) nanoagent γ-Fe₂O₃ and GdPO₄ nanoparticles (Fe-Gd/HCS), were successfully prepared and applied to in vitro/vivo evaluation with well-defined sizes of ∼100 nm (Fe-Gd/HCS-S), ∼200 nm (Fe-Gd/HCS-M), and ∼300 nm (Fe-Gd/HCS-L), respectively. Then the in vitro size effect of Fe-Gd/HCS was systematically investigated by bio-TEM, CLSM, CCK-8 assay, and flow cytometry revealing that Fe-Gd/HCS could be internalized and the cellular uptake amounts increase with the decrease of size. Furthermore, the in vivo size-effect behavior of Fe-Gd/HCS (∼100 nm, ∼200 nm, ∼300 nm) was tracked by MRI technique, demonstrating that all Fe-Gd/HCS can distinguish the liver, in which Fe-Gd/HCS with the smallest particle size exhibited the best performance among these nanoparticles. By leveraging on these features, Fe-Gd/HCS-S (∼100 nm) was further chosen as a theranostic agent, preliminarily presenting its capability for multi-modal imaging and therapy.

Progress of biomaterials for bone tumor therapy

Bone tumors are currently a major clinical challenge. In recent decades, strategies using well-designed versatile biomaterials for the treatment of bone tumors have emerged and attracted extensive research interest. Suitable biomaterials not only facilitate repair for bone defects aroused by surgical intervention but also help deliver antineoplastic drugs to the target site or provide photothermal/magnetothermal therapy to kill bone tumor cells. Thus, the development of biomaterials exhibits a great perspective for future bone tumor treatment.We summarize the recent progress of versatile biomaterials for bone tumor therapy, with an emphasis on photothermal/magnetothermal therapy and drug delivery.With the further understanding and development of biomaterials, multifunctional biomaterials have been proposed for bone tumor treatment. Through the interdisciplinary cooperation from the fields of biomedicine, clinical medicine and engineering, multifunctional biomaterials will perfectly match individual bone defects in the clinic with low cost in the future.

An Electromagnetic Microwave Stealth Photothermal Soft Actuator with Lightweight and Hydrophobic Properties

Electromagnetic (EM) microwave stealth soft robots are in urgent need in military application. Photothermal soft actuators with photomechanical energy conversion have attracted significant interest owing to their remote control, flexibility, and contactless operation. The innovative combination of an electromagnetic microwave absorption (EMA) function with a photothermal actuator paves the way for this aspect. Here, a composite with unique dual three-dimensional foam is fabricated based on graphene and hollow carbon spheres (HCSs). When exposed to 1 sun illumination, the temperature could increase to 50 °C within 1 min and plateaus at 80 °C for hollow carbon spheres-graphene foam-polydimethylsiloxane (HCSs-GF-PDMS), which shows great photothermal performance. A wormlike crawling robot has been constructed based on this composite material, which could move forward under only 1 sun illumination. Remarkably, the EM stealth could be successfully realized because the composite material exhibits great EMA performance with a minimum reflection loss of -56.99 dB at a thickness of 2.5 mm, and the maximum effective absorption bandwidth is 8.65 GHz. In addition, the HCSs-GF exhibits hydrophobic and lightweight functions as well, which lighten the weight of soft robots and lead to self-cleaning and energy saving. This work provides a promising direction of multifunctional EM stealth soft robots.

Hollow carbon nanospheres dotted with Gd-Fe nanoparticles for magnetic resonance and photoacoustic imaging

Integrating magnetic resonance (MR) and photoacoustic (PA) contrast agents into porous nanomaterials is a favorable way for screening of potential theranostic nanomedicines. Hollow carbon nanospheres (HCSs) dotted with GdPO₄ and γ-Fe₂O₃ (Gd-Fe) nanoparticles are therefore prepared and studied in this work. The resultant Gd-Fe/HCSs possess a size of ∼100 nm with a cavity of ∼80 nm and a shell thickness of ∼10 nm, where the magnetic Gd-Fe nanoparticles are dotted. Owing to the synergistic effects, the Gd-Fe/HCSs give 2.5 times enhanced PA signals as compared with HCSs as well as the inherited MR imaging properties from Gd-Fe nanoparticles. In vivo MR and PA imaging of the liver in mice are consequently evaluated and validated. Furthermore, taking the tunable particle size, hollow cavity, shell thickness, and dotted amounts of nanoparticles into consideration, our studies here provide a useful structural model for the synergistic integration of MR and PA imaging in HCSs.

A novel multifunctional carbon aerogel-coated platform for osteosarcoma therapy and enhanced bone regeneration

Nowadays, groundbreaking strategies are urgently needed to address drug resistance, osteolysis, bone defects and other predicaments impeding the therapeutic efficacy of osteosarcoma. Among them, photothermal therapy (PTT), using systematically administrated nanoagents, exhibits attractive therapeutic efficacy, yet is powerless in bone defect regeneration. Herein, a novel multifunctional beta-tricalcium phosphate (β-Ca3(PO4)2, β-TCP) bioceramic platform-coated with carbon aerogel (CA), which was initially developed for tumor therapy, was fabricated. On account of the desirable photothermal capabilities of CA, sufficient hyperthermia is generated under the irradiation of an 808 nm laser to achieve a thorough ablation of osteosarcoma tumors. Furthermore, CA-coated surfaces provide extra roughness and a higher specific surface area, which promoted the protein recruitment ability and osteogenesis via a fibronectin (FN)-mediated signaling pathway. The photothermal therapeutic efficacy and osteogenesis capability of CA-coated β-TCP-C suggests a novel approach for the treatment of osteosarcoma and provides provoking inspiration for the prospective bio-application of CA.

Exploiting Co Defects in CoFe-Layered Double Hydroxide (CoFe-LDH) Derivatives for Highly Efficient Photothermal Cancer Therapy

Currently, two-dimensional materials are being actively pursued in catalysis and other fields due their abundance of defects, which results in enhanced performance relative to their bulk defect-free counterparts. To date, the exploitation of defects in two-dimensional materials to enhance photothermal therapies has received little attention, motivating a detailed investigation. Herein, we successfully fabricated a series of novel CoFe-based photothermal agents (CoFe-x) by heating CoFe-layered double hydroxide (CoFe-LDH) nanosheets at different temperatures (x) between 200-800 °C under a Ar atmosphere. The CoFe-x products differed in their particle size, cobalt defect concentration, and electronic structure, with the CoFe-500 product containing the highest concentration of Co²⁺ defects and most efficient photothermal performance under near-infrared (NIR, 808 nm) irradiation. Experiments and density functional theory (DFT) calculations revealed that Co²⁺ defects modify the electronic structure of CoFe-x, narrowing the band gap and thus increasing the nonradiative recombination rate, thereby improving the NIR-driven photothermal properties. In vitro and in vivo results demonstrated that CoFe-500 was an efficient agent for photothermal cancer treatment and also near-infrared (NIR) thermal imaging, magnetic resonance (MR) imaging, and photoacoustic (PA) imaging. This work provides valuable new insights about the role of defects in the rational design of nanoagents with optimized structures for improved cancer therapy.

Chemical Modification of Biomass Okara Using Poly(acrylic acid) through Free Radical Graft Polymerization

Okara (Ok) or soybean residue is produced as a byproduct from the soybean milk and soybean curd industries world wide, most of which is disposed or burned as waste. It is important to explore the possibilities to convert okara to useful materials, because okara is a naturally renewable bioresource. Here, we report the chemical modification of okara by grafting poly(acrylic acid) (PAA) onto the backbones of okara in water medium and the characterization of the Ok-PAA graft copolymers. It was found that the received okara mainly contained insoluble contents in water. The insoluble okara component Ok(Ins) was suspended in water and activated with ammonium persulfate as an initiator, followed by grafting PAA through a free radical polymerization. After the graft polymerization, the product (Ok-PAA) was separated into precipitate and supernatant, which were dried to give Ok-PAA(pre) and Ok-PAA(sup), respectively. It was found that PAA was grafted on Ok backbones and co-precipitated with the insoluble Ok. In addition, Ok-PAA(sup) was found to be translucent as a result of the grafting of PAA. Further, the successful grafting of PAA onto okara backbones was proven by Fourier transform infrared, thermogravimetric analysis, and microscopic measurements. Ok-PAA(sup) dispersed in water formed nanoparticles with an average diameter of 420 nm, while Ok-PAA(pre) was clustered coarse particles in water. The rheological data including the storage modulus, loss modulus, and viscosity indicated that the Ok-PAA product was a viscoelastic gel-like material with potential for agricultural and environmental applications.

Highly efficient photothermal heating via distorted edge-defects in boron quantum dots

Quantum dots (QDs) are increasingly being utilized as near infrared (NIR) active photothermal agents for cancer diagnosis and therapy, with the main emphasis of current research being the enhancement of photothermal conversion efficiencies. Herein, we report the facile synthesis of 2-3 nm boron quantum dots (B QDs), which demonstrated a remarkable photothermal conversion efficiency of 57% under NIR excitation. This outstanding performance can be attributed to the alteration of the electronic structure, which was a result from the distorted edge-effect induced by the unique empty orbit of B atoms in the B QDs. These results can be verified by B K-edge near edge X-ray absorption fine structure (NEXAFS), high-resolution transmission electron microscopy (HR-TEM) and density functional theory (DFT) calculations. The results demonstrate that B QDs represent a promising new and non-toxic agent for both multimodal NIR-driven cancer imaging and photothermal therapy. This work thus identifies B QDs as an exciting new and theranostic agent for cancer therapy. Furthermore, the synthetic strategy used here to synthesize the B QDs was simple and easily scalable.

Photothermal Response of Polyhydroxy Fullerenes

Photothermal therapy, utilizing photonic nanoparticles, has gained substantial interest as an alternative to systemic cancer treatments. Several different photothermal nanoparticles have been designed and characterized for their photothermal efficiency. However, a standardized experimental methodology to determine the photothermal efficiency is lacking leading to differences in the reported values for the same nanoparticles. Here, we have determined the role of different experimental parameters on the estimation of photothermal efficiency. Importantly, we have demonstrated the role of laser irradiation time and nanoparticle concentration as the two critical factors that can lead to errors in the estimation of photothermal efficiency. Based on the optimized parameters, we determined the photothermal conversion efficiency of polyhydroxy fullerenes to be 69%. Further, the photothermal response of polyhydroxy fullerenes was found to be stable with repeated laser irradiation and no changes in the molecular structure were observed. Given its high photothermal efficiency and superior stability, polyhydroxy fullerenes are an ideal candidate for photothermal therapy.

Defective Porous Carbon Polyhedra Decorated with Copper Nanoparticles for Enhanced NIR-Driven Photothermal Cancer Therapy

Currently, there is tremendous interest in the discovery of new and improved photothermal agents for near-infrared (NIR)-driven cancer therapy. Herein, a series of novel photothermal agents, comprising copper nanoparticles supported on defective porous carbon polyhedra are successfully prepared by heating a Cu-BTC metal-organic framework (MOF) precursor at different temperatures (t) in the range 400-900 °C under an argon atmosphere. The copper nanoparticle size and carbon defect concentration in the obtained products (denoted herein as Cu@CPP-t) increase with synthesis temperature, thus imparting the Cu@CPP-t samples with distinct NIR absorption properties and photothermal heating responses. The Cu@CPP-800 sample shows a remarkable photothermal conversion efficiency of 48.5% under 808 nm laser irradiation, representing one of the highest photothermal efficiencies yet reported for a carbon-based photothermal agent. In vivo experiments conducted with tumor bearing nude Balb/c mice confirm the efficacy of Cu@CPP-800 as a very promising NIR-driven phototherapy agent for cancer treatment. Results encourage the wider use of MOFs as low cost precursors for the synthesis of carbon-supported metal nanoparticle composites for photothermal therapy.

Polypyrrole-based double rare earth hybrid nanoparticles for multimodal imaging and photothermal therapy

A polypyrrole-based theranostic agent containing double rare-earth elements was constructed and demonstrated promising application for T₁/T₂-weighted MRI/CT tri-modal imaging guided photothermal cancer therapy.

A carbon nanomaterial derived from a nanoscale covalent organic framework for photothermal therapy in the NIR-II biowindow

A nanoscale carbon nanomaterial was synthesized through pyrolysis of its NCOF precursor, and the obtained carbon nanoparticles (CNPs) can be highly efficient NIR-II photothermal agents for antitumor treatment via PTT.

N-Doped Carbon Quantum Dot (NCQD)-Deposited Carbon Capsules for Synergistic Fluorescence Imaging and Photothermal Therapy of Oral Cancer

Use of nanomaterials blessed with both therapeutic and diagnostic properties is a proficient strategy in the treatment of cancer in its early stage. In this context, our paper reports the synthesis of uniform size N-rich mesoporous carbon nanospheres of size 65-70 nm from pyrrole and aniline precursors using Triton-X as a structure-directing agent. Transmission electron microscopy reveals that these carbons spheres contain void spaces in which ultrasmall nitrogen-doped quantum dots (NCQD) are captured within the matrix. These mesoporous hollow NCQD captured carbon spheres (NCQD-HCS) show fluorescence quantum yield up to 14.6% under λ_ex = 340 nm. Interestingly, samples calcined at >800 °C clearly absorb in the wavelength range 700-1000 nm and shows light-to-heat conversion efficiency up to 52%. In vitro experiments in human oral cancer cells (FaDu) show that NCQD-HCS are internalized by the cells and induce a substantial thermal ablation effect in FaDu cells when exposed under a 980 nm near-infrared laser.