Mitochondria-targeting photoacoustic therapy using single-walled carbon nanotubes

Nanomaterials in Medicine: Understanding Cellular Uptake, Localization, and Retention for Enhanced Disease Diagnosis and Therapy

Nanomaterials (NMs) have emerged as promising tools for disease diagnosis and therapy due to their unique physicochemical properties. To maximize the effectiveness and design of NMs-based medical applications, it is essential to comprehend the complex mechanisms of cellular uptake, subcellular localization, and cellular retention. This review illuminates the various pathways that NMs take to get from the extracellular environment to certain intracellular compartments by investigating the various mechanisms that underlie their interaction with cells. The cellular uptake of NMs involves complex interactions with cell membranes, encompassing endocytosis, phagocytosis, and other active transport mechanisms. Unique uptake patterns across cell types highlight the necessity for customized NMs designs. After internalization, NMs move through a variety of intracellular routes that affect where they are located subcellularly. Understanding these pathways is pivotal for enhancing the targeted delivery of therapeutic agents and imaging probes. Furthermore, the cellular retention of NMs plays a critical role in sustained therapeutic efficacy and long-term imaging capabilities. Factors influencing cellular retention include nanoparticle size, surface chemistry, and the cellular microenvironment. Strategies for prolonging cellular retention are discussed, including surface modifications and encapsulation techniques. In conclusion, a comprehensive understanding of the mechanisms governing cellular uptake, subcellular localization, and cellular retention of NMs is essential for advancing their application in disease diagnosis and therapy. This review provides insights into the intricate interplay between NMs and biological systems, offering a foundation for the rational design of next-generation nanomedicines.

Hollow Cavity CaO2 @Polydopamine Nanocomposites for pH-Responsive Ca2+ -Enhanced Efficient Mild Hyperthermia in the NIR-II Region

Second near-infrared (NIR-II) mild photothermal therapy with higher tissue penetration depth and less damage to healthy tissues is emerging as an attractive antitumor modality, but its therapeutic efficiency is dramatically suppressed by the resistance of heat shock proteins (HSPs). As a widely explored photothermal agent, the application of polydopamine (PDA) in the NIR-II region is hampered by low photothermal conversion efficiency (PCE). Herein, its PCE in the NIR-II region is improved by developing novel hollow cavity CaO2 @PDA nanocomposites through chelation-induced diffusion of inner core Ca2+ to the shell PDA to facilitate multiple reflections of laser in the cavity. Upon pH-responsive degradation of CaO2 , its structure is transformed into a stacked "nano-mesh" with excellent light absorption and an enlarged effective irradiation area. Overloading of Ca2+ ions not only induces downregulation of HSPs but also enhances interference of light on membrane potential, which further aggravate mitochondrial dysfunction and reduce the thermotolerance of tumor cells, promoting efficient mild hyperthermia of PDA in the NIR-II region.

Imaging-Guided Photoacoustic Immunotherapy Based on the Polydopamine-Functionalized Black Phosphorus Nanocomposites

Phototherapy has great application prospects in superficial tumors, such as melanoma, esophageal cancer, and breast carcinoma, owing to the advantages of noninvasiveness, high spatiotemporal selectivity, and less side effects. However, classical phototherapies including photodynamic and photothermal therapy still need to settle the bottleneck problems of poor efficacy, inevitable thermal damage, and a high rate of postoperative recurrence. In this study, we developed a nanocomposite with excellent optical properties and immune-stimulating properties, termed PBP@CpG, which was obtained by functionalizing black phosphorus (BP) with polydopamine and further adsorbing CpG. Benefiting from the protection of polydopamine against BP, ideal light absorption, and photoacoustic conversion properties, PBP@CpG not only enables precisely delineation of the tumor region with photoacoustic imaging but also powerfully disrupts the plasma membrane and cytoskeleton of tumor cells with a photoacoustic cavitation effect. In addition, we found that the photoacoustic cavitation effect was also capable of inducing immunogenic cell death and remarkably strengthening the antitumor immune response upon cooperating with immune adjuvant CpG. Therefore, PBP@CpG was expected to provide a promising nanoplatform for optical theranostics and herald a new strategy of photoimmunotherapy based on the photoacoustic cavitation effects and immunostimulatory effect.

Functional Materials for Subcellular Targeting Strategies in Cancer Therapy: Progress and Prospects

Neoadjuvant and adjuvant therapies have made significant progress in cancer treatment. However, tumor adjuvant therapy still faces challenges due to the intrinsic heterogeneity of cancer, genomic instability, and the formation of an immunosuppressive tumor microenvironment. Functional materials possess unique biological properties such as long circulation times, tumor-specific targeting, and immunomodulation. The combination of functional materials with natural substances and nanotechnology has led to the development of smart biomaterials with multiple functions, high biocompatibilities, and negligible immunogenicities, which can be used for precise cancer treatment. Recently, subcellular structure-targeting functional materials have received particular attention in various biomedical applications including the diagnosis, sensing, and imaging of tumors and drug delivery. Subcellular organelle-targeting materials can precisely accumulate therapeutic agents in organelles, considerably reduce the threshold dosages of therapeutic agents, and minimize drug-related side effects. This review provides a systematic and comprehensive overview of the research progress in subcellular organelle-targeted cancer therapy based on functional nanomaterials. Moreover, it explains the challenges and prospects of subcellular organelle-targeting functional materials in precision oncology. The review will serve as an excellent cutting-edge guide for researchers in the field of subcellular organelle-targeted cancer therapy.

Pulsed Microwave-Induced Thermoacoustic Shockwave for Precise Glioblastoma Therapy with the Skin and Skull Intact

Glioblastoma has a dismal prognosis and is a critical and urgent health issue that requires aggressive research and determined clinical efforts. Due to its diffuse and infiltrative growth in the brain parenchyma, complete neurosurgical resection is rarely possible. Here, pulsed microwave-induced thermoacoustic (MTA) therapy is proposed as a potential alternative modality to precisely and effectively eradicate in vivo orthotopic glioblastoma. A nanoparticle composed of polar amino acids and adenosine-based agonists is constructed with high microwave absorbance and selective penetration of the blood-brain barrier (BBB) at the tumor site. This nanoparticle can activate the adenosine receptor on the BBB to allow self-passage and tumor accumulation. The nanoparticle converts absorbed microwaves into ultrasonic shockwaves via the thermoacoustic cavitation effect. The ultrasonic shockwave can mechanically destroy tumor cells within a short range with minimal damage to adjacent normal brain tissue due to the rapid decay of the ultrasonic shockwave intensity. The deep tissue penetration characteristics of the microwave and the rapid decay of the ultrasonic shockwave make MTA therapy a promising glioblastoma cure including intact skin and skull.

Application of a cationic amylose derivative loaded with single-walled carbon nanotubes for gene delivery therapy and photothermal therapy of colorectal cancer

Single-walled carbon nanotubes (SWNTs) are cylindrical graphitic helix molecules that exhibit superb mechanical and physical properties. Many polymers, such as polyethylene glycol and glycated chitosan, have been used to modify SWNTs to enhance the stability and biocompatibility of delivery systems; thus, a novel modification for SWNTs with amylose derivatives containing poly(L-lysine) dendrons (ADP@SWNT) is developed. Infrared spectra analysis, ¹ H NMR analysis, circular dichroism spectra analysis and thermogravimetric analysis are used to characterize and confirm complex formation. The aqueous dispersion stability, cytotoxicity, gene transfection efficiency and photothermal effect of the complex are studied in vitro and in vivo. Results suggest that the ADP@SWNT complex is successfully synthesized with good water dispersion stability and pDNA transfection capacity. ADP@SWNT/TNFα inhibits tumor growth and metastasis both in vivo and in vitro, and the anti-tumor effect is enhanced by NIR irradiation, suggesting its high potential for application in tumor therapy.

Pulsed Laser Excited Photoacoustic Effect for Disease Diagnosis and Therapy

Pulsed laser can excite light absorber to generate photoacoustic (PA) effect, that is, when the absorber is irradiated with pulsed laser, the absorbed light energy is converted into local heat to cause rapid thermoelastic expansion and generate acoustic wave. The generated PA signal has been widely employed for the diagnosis of many diseases with superb contrast, high penetrability and sensitivity. In addition, with the increase of pulsed laser energy, the resulting PA shockwave and cavitation can promote efficient drug release at lesion sites to potentiate the resulting therapeutic efficacy. Furthermore, the PA shockwave/cavitation can mechanically inhibit disease and produce reactive species. In this Concept article, the principle and research status of pulsed laser excited disease theranostics are briefly summarized, extra suggestions are proposed to inspire extensive PA probes and photodynamic materials as well as novel methodologies.

Undifferentiated destruction of mitochondria by photoacoustic shockwave to overcome chemoresistance and radiation resistance in cancer therapy

Resistance to either radiation or chemotherapy remains a complex and stubborn obstacle in cancer therapy and is responsible for a significant portion of the treatment failure. While the underlying mechanisms of the resistance are often associated with multiple factors, direct destruction of mitochondria is likely to ensure the ultimate death of the cell. Herein, a strategy of precise mitochondrial destruction using a photoacoustic (PA) shockwave was proposed to overcome chemoresistance and radiation resistance in cancer therapy. A nanoparticle featuring mitochondria-targeting and high near-infrared absorbance is constructed. The nanoparticle was found to indiscriminately localize in the mitochondria of both parental and its corresponding resistant tumor cells due to the mitochondrial transmembrane potential. By absorbing a controllable amount of energy from a pulsed laser, the nanoparticle could generate a mechanical PA shockwave that physically damages the mitochondria leading to the opening of apoptotic pathways and thus yielding a precision antitumor effect. The cell-killing efficiency was validated in vitro and in vivo. The results demonstrate that a PA shockwave can result in undifferentiated killing of the resistant tumor cells via destruction of mitochondria. Given the critical importance of resistant tumor cells, although at its preliminary stage, the proposed modality may open a new window in cancer therapy.

Insights on functionalized carbon nanotubes for cancer theranostics

Despite the exciting breakthroughs in medical technology, cancer still accounts for one of the principle triggers of death and conventional therapeutic modalities often fail to attain an effective cure. Recently, nanobiotechnology has made huge advancement in cancer therapy with gigantic application potential because of their ability in achieving precise and controlled drug release, elevating drug solubility and reducing adverse effects. Carbon nanotubes (CNTs), one of the most promising carbon-related nanomaterials, have already achieved much success in biomedical field. Due to their excellent optical property, thermal and electronic conductivity, easy functionalization ability and high drug loading capacity, CNTs can be applied in a multifunctional way for cancer treatment and diagnosis. In this review, we will give an overview of the recent progress of CNT-based drug delivery systems in cancer theranostics, which emphasizes their targetability to intracellular components of tumor cells and extracellular elements in tumor microenvironment. Moreover, a detailed introduction on how CNTs penetrate inside the tumor cells to reach their sites of action and achieve the therapeutic effects, as well as their diagnostic applications will be highlighted.

Recent Progress on Molecular Photoacoustic Imaging with Carbon-Based Nanocomposites

For biomedical imaging, the interest in noninvasive imaging methods is ever increasing. Among many modalities, photoacoustic imaging (PAI), which is a combination of optical and ultrasound imaging techniques, has received attention because of its unique advantages such as high spatial resolution, deep penetration, and safety. Incorporation of exogenous imaging agents further amplifies the effective value of PAI, since they can deliver other specified functions in addition to imaging. For these agents, carbon-based materials can show a large specific surface area and interesting optoelectronic properties, which increase their effectiveness and have proved their potential in providing a theragnostic platform (diagnosis + therapy) that is essential for clinical use. In this review, we introduce the current state of the PAI modality, address recent progress on PAI imaging that takes advantage of carbon-based agents, and offer a future perspective on advanced PAI systems using carbon-based agents.

Ultrahigh Sensitive and Tumor-Specific Photoacoustography in NIR-II Region: Optical Writing and Redox-Responsive Graphic Fixing by AgBr@PLGA Nanocrystals

The highly up-regulated glutathione (GSH) concentration in the tumor microenvironment is generally identified to be an effective endogenous characteristic of cancerous tissues. Herein, an ultrahigh-sensitive and tumor-specific photoacoustography technique in the near-infrared (NIR-II) region based on optical writing and redox-responsive chromogenic graphic fixing is developed by introducing a self-synthesized photosensitive silver bromide modified with poly lactic-co-glycolic acid (AgBr@PLGA) nanocrystals. After they are optically triggered by external light, the NIR-transparent AgBr@PLGA nanocrystals can be reduced by the tumor-abundant GSH into strongly absorbing silver nanoparticles, significantly boosting the "turn-on" photoacoustic (PA) signal in the NIR-II region; therefore, the tumor area can be graphically fixed and developed in the photoacoustography. Experiments on both in vitro phantoms and in vivo mouse models demonstrate that the tumor area is specifically identified by the photoacoustography with the background signals effectively suppressed by dynamically modulating the exposure time. The tumor-specific photoacoustography technique prefigures great potential for high-precision cancer diagnosis and treatment monitoring.

Hollow carbon-based nanosystem for photoacoustic imaging-guided hydrogenothermal therapy in the second near-infrared window

Compared with the near-infrared-I spectral window (NIR-I, 650-950 nm), a newly developed imaging and treatment window with a 1000-1700 nm range (defined as the NIR-II bio-window) has attracted much attention owing to its higher spatiotemporal resolution, increased tissue penetration depth and therapeutic efficacy. Herein, we designed a nanotheranostic platform (HC-AB NPs) via loading ammonia borane (AB) into hollow carbon nanoparticles (HCs) for NIR-II photoacoustic (PA) imaging-guided NIR-II hydrogenothermal therapy. Importantly, by exploiting the characteristics of beta zeolite as a hard template and a template-carbonization-corrosion process, the prepared HCs have excellent NIR-II absorption performance and AB loading capacity. With the high biocompatibility of HC-AB NPs, an efficient synergistic anti-tumor strategy has been achieved via high intratumoural accumulation and acid-stimulated H2 release as well as PA-guided precise NIR-II photothermal therapy. The HC-AB NPs as a promising nanotheranostic platform opens a new avenue for high-efficacy NIR-II hydrogenothermal therapy.

Photoacoustic-immune therapy with a multi-purpose black phosphorus-based nanoparticle

Effective therapeutic strategies to precisely eradicate primary tumors with minimal side effects on normal tissue, inhibit metastases, and prevent tumor relapses, are the ultimate goals in the battle against cancer. We report a novel therapeutic strategy that combines adjuvant black phosphorus nanoparticle-based photoacoustic (PA) therapy with checkpoint-blockade immunotherapy. With the mitochondria targeting nanoparticle, PA therapy can achieve localized mechanical damage of mitochondria via PA cavitation and thus achieve precise eradication of the primary tumor. More importantly, PA therapy can generate tumor-associated antigens via the presence of the R848-containing nanoparticles as an adjuvant to promote strong antitumor immune responses. When combined with the checkpoint-blockade using anti-cytotoxic T-lymphocyte antigen-4, the generated immunological responses will further promote the infiltrating CD8 and CD4 T-cells to increase the CD8/Foxp3 T-cell ratio to inhibit the growth of distant tumors beyond the direct impact range of the PA therapy. Furthermore, the number of memory T cells detected in the spleen is increased, and these cells inhibit tumor recurrence. This proposed strategy offers precise eradication of the primary tumor and can induce long-term tumor-specific immunity.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material is available for this article at 10.1007/s12274-020-3028-x and is accessible for authorized users.

Rational collaborative ablation of bacterial biofilms ignited by physical cavitation and concurrent deep antibiotic release

Bacteria biofilm has extracellular polymeric substances to protect bacteria from external threats, which is a stubborn problem for human health. Herein, a kind of gasifiable nanodroplet is fabricated to ablate Staphylococcus aureus (S. aureus) biofilm. Upon NIR pulsed laser irradiation, the nanodroplets can gasify to generate destructive gas shockwave, which further potentiates initial acoustic cavitation effect, thus synergistically disrupting the protective biofilm and killing resident bacteria. More importantly, the gasification can further promote antibiotic release in deep biofilm for residual bacteria eradication. The nanodroplets not only exhibit deep biofilm penetration capacity and high potency to ablate biofilms, but also good biocompatibility without detectable side effects. In vivo mouse implant model indicates that the nanodroplets can accumulate at the S. aureus infected implant sites. Upon pulsed laser treatment, the nanodroplets efficiently eradicate bacteria biofilm in implanted catheter by synergistic contribution of gas shockwave-enhanced cavitation and deep antibiotic release. Current phase changeable nanodroplets with synergistic physical and chemical therapeutic modalities are promising to combat complex bacterial biofilms with drug resistance, which provides an alternative visual angle for biofilm inhibition in biomedicine.

Modeling of cancer photothermal therapy using near-infrared radiation and functionalized graphene nanosheets

Photothermal therapy using near-infrared radiation and local heating agents can induce selective tumor ablation with limited harm to the surrounding normal tissue. Graphene sheets are promising local heating agents because of their strong absorbance of near-infrared radiation. Experimental studies have been conducted to study the heating effect of graphene in photothermal therapy, yet few efforts have been devoted to the quantitative understanding of energy conversion and transport in such systems. Herein, a computational study of cancer photothermal therapy using near-infrared radiation and graphene is presented using a Monte Carlo approach. A three-dimensional model was built with a cancer cell inside a cube of healthy tissue. Functionalized graphene nanosheets were randomly distributed on the surface of the cancer cell. The effects of the concentration and morphology of the graphene nanosheets on the thermal behavior of the system were quantitatively investigated. The interfacial thermal resistance around the graphene sheets, which affects the transfer of heat in the nanoscale, was also varied to probe its effect on the temperature increase of the cancer cell and the healthy tissue. The results of this study could guide researchers to optimize photothermal therapy with graphene, while the modeling approach has the potential to be applied for investigating alternative treatment plans.

Magnetic-induced graphene quantum dots for imaging-guided photothermal therapy in the second near-infrared window

Graphene quantum dots (GQDs) are considered emerging nanomaterials for photothermal therapy (PTT) of cancer due to their good biocompatibility and rapid excretion. However, the optical absorbance of GQDs in shorter wavelengths (<1000 nm) limits their overall therapeutic efficacies as photothermal agent in the second near infrared window (1000-1700 nm, NIR-II). Herein, we report a type of GQDs with strong absorption (1070 nm) in NIR-II region that was synthesized via a one-step solvothermal treatment using phenol as single precursor by tuning the decomposition of hydrogen peroxide under a high magnetic field with an intensity of 9T. The obtained 9T-GQDs demonstrate uniform size distribution (3.6 nm), and tunable fluorescence (quantum yield, 16.67%) and high photothermal conversion efficacy (33.45%). In vitro and in vivo results indicate that 9T-GQDs could efficiently ablate tumor cells and inhibit the tumor growth under NIR-II irradiation. Moreover, the 9T-GQDs exhibited enhanced NIR imaging of tumor in living mice, suggesting the great probability of using 9T-GQDs for in vivo NIR imaging-guided PTT in the NIR-II window.

Controlling the Dissolution Rate of Hydrophobic Drugs by Incorporating Carbon Nanotubes with Different Levels of Carboxylation

We present the anti-solvent precipitation of hydrophobic drugs griseofulvin (GF) and sulfamethoxazole (SMZ) in the presence of carboxylated carbon nanotubes (f-CNTs). The aqueous dispersed f-CNTs were directly incorporated into the drug particles during the precipitation process. f-CNTs with different levels of carboxylation were tested where the hydrophilicity was varied by altering the C:COOH ratio. The results show that the hydrophilic f-CNTs dramatically enhanced the dissolution rate for both drugs, and the enhancement corresponded to the hydrophilicity of f-CNTs. The time to reach 80% dissolution (t80) reduced from 52.5 min for pure SMZ to 16.5 min when incorporated f-CNTs that had a C:COOH ratio of 23.2 were used, and to 11.5 min when the ratio dropped to 16. A corresponding decrease was observed for SMZ for the above-mentioned f-CNTs. The study clearly demonstrates that it is possible to control the dissolution rate of hydrophobic drugs by altering the level of carboxylation of the incorporated CNTs.

A photoacoustic shockwave triggers the size shrinkage of nanoparticles to obviously improve tumor penetration and therapeutic efficacy

Drug delivery to a tumor site with an insufficient microvascular network remains a challenge due to the size preference for transport in terms of circulation and distribution. In this work, an integrated nano-therapeutic parcel disintegrable by a photoacoustic shockwave was developed. Nano-therapeutic particles with red absorbance are packaged into a larger parcel to generate a longer circulation half-life and improved accumulation in tumor tissue. Pulse-laser irradiation is absorbed by the nanoparticles and it generates a photoacoustic shockwave. This triggers a liquid-gas phase transition of the nano-parcel, leading to the high-efficiency release of smaller nanoparticles, thus achieving excellent therapeutic diffusion with improved uniformity. This results in a highly effective therapeutic effect, as demonstrated with both in vitro and in vivo tumor models. Compared to previously reported work, this approach has the distinctive advantage of precisely controllable therapeutic release that is independent of the physiological environment in the tumor and it is less limited than a UV-based release mechanism. In addition, the concept of photoacoustic shockwave-based nanoparticle release can be extended over a wide wavelength range, including microwaves, to match specific needs and achieve optimal therapeutic depth. The results demonstrate that the proposed strategy holds great potential for improved tumor therapy efficacy.

Incorporation of functionalized carbon nanotubes into hydrophobic drug crystals for enhancing aqueous dissolution

We present for the first time the direct incorporation of carboxylated carbon nanotubes (f-CNTs) into hydrophobic drug particles during their formation via anti-solvent precipitation. The approach was tested using two drugs namely antifungal agent Griseofulvin (GF) and antibiotic Sulfamethoxazole (SMZ) that had very different aqueous solubility. It was observed that the f-CNTs dispersed in the water served as nucleating sites for crystallization and were readily incorporated into the drug particles without altering crystal structure or other properties. The results showed that the hydrophilic f-CNTs dramatically enhanced dissolution rate for both drugs, and the time necessary to reach 80% dissolution (t80) reduced from 67 to 10 with the incorporation of 5.1% f-CNTs in SMZ, and from 66 to 18 min with 4.0% f-CNTs in GF. The enhanced dissolution is attributed to the fact that the hydrophilic f-CNTs served as conduits for bringing in water in close contact with the drug crystals.

Current concepts in nanostructured contrast media development for in vivo photoacoustic imaging

To overcome the endogenous photoacoustic contrast arising from endogenous species, specific contrast agents need to be developed, allowing PAI to successfully identify targeted contrast in the range of wavelength in which the interference from the biomatrix is minimized.

Nanotechnology-based photoimmunological therapies for cancer

Phototherapy is a non-invasive or minimally invasive therapeutic strategy. Immunotherapy uses different immunological approaches, such as antibodies, vaccines, immunoadjuvants, and cytokines to stimulate the host immune system to fight against diseases. In cancer treatment, phototherapy not only destroys tumor cells, but also induces immunogenic tumor cell death to initiate a systemic anti-tumor immune response. When combined with immunotherapy, the effectiveness of phototherapy can be enhanced. Because of their special physical, chemical, and sometimes immunological properties, nanomaterials have also been used to enhance phototherapy. In this article, we review the recent progress in nanotechnology-based phototherapy, including nano-photothermal therapy, nano-photochemical therapy, and nano-photoimmunological therapy in cancer treatment. Specifically, we focus on the immunological responses induced by nano-phototherapies.

C60 fullerene accumulation in human leukemic cells and perspectives of LED-mediated photodynamic therapy

Recent progress in nanobiotechnology has attracted interest to a biomedical application of the carbon nanostructure C₆₀ fullerene since it possesses a unique structure and versatile biological activity. C₆₀ fullerene potential application in the frame of cancer photodynamic therapy (PDT) relies on rapid development of new light sources as well as on better understanding of the fullerene interaction with cells. The aim of this study was to analyze C₆₀ fullerene effects on human leukemic cells (CCRF-CEM) in combination with high power single chip light-emitting diodes (LEDs) light irradiation of different wavelengths: ultraviolet (UV, 365 nm), violet (405 nm), green (515 nm) and red (632 nm). The time-dependent accumulation of fullerene C₆₀ in CCRF-CEM cells up to 250 ng/10⁶ cells at 24 h with predominant localization within mitochondria was demonstrated with immunocytochemical staining and liquid chromatography mass spectrometry. In a cell viability assay we studied photoexcitation of the accumulated C₆₀ nanostructures with ultraviolet or violet LEDs and could prove that significant phototoxic effects did arise. A less pronounced C₆₀ fullerene phototoxic effect was observed after irradiation with green, and no effect was detected with red light. A C₆₀ fullerene photoactivation with violet light induced substantial ROS generation and apoptotic cell death, confirmed by caspase3/7 activation and plasma membrane phosphatidylserine externalization. Our work proved C₆₀ fullerene ability to induce apoptosis of leukemic cells after photoexcitation with high power single chip 405 nm LED as a light source. This underlined the potential for application of C₆₀ nanostructure as a photosensitizer for anticancer therapy.

Through Scalp and Skull NIR-II Photothermal Therapy of Deep Orthotopic Brain Tumors with Precise Photoacoustic Imaging Guidance

Brain tumor is one of the most lethal cancers owing to the existence of blood-brain barrier and blood-brain tumor barrier as well as the lack of highly effective brain tumor treatment paradigms. Herein, cyclo(Arg-Gly-Asp-D-Phe-Lys(mpa)) decorated biocompatible and photostable conjugated polymer nanoparticles with strong absorption in the second near-infrared (NIR-II) window are developed for precise photoacoustic imaging and spatiotemporal photothermal therapy of brain tumor through scalp and skull. Evidenced by the higher efficiency to penetrate scalp and skull for 1064 nm laser as compared to common 808 nm laser, NIR-II brain-tumor photothermal therapy is highly effective. In addition, via a real-time photoacoustic imaging system, the nanoparticles assist clear pinpointing of glioma at a depth of almost 3 mm through scalp and skull with an ultrahigh signal-to-background ratio of 90. After spatiotemporal photothermal treatment, the tumor progression is effectively inhibited and the survival spans of mice are significantly extended. This study demonstrates that NIR-II conjugated polymer nanoparticles are promising for precise imaging and treatment of brain tumors.

Integrated photoacoustic microscopy, optical coherence tomography, and fluorescence microscopy for multimodal chorioretinal imaging

Current clinically available retinal imaging techniques have limitations, including limited depth of penetration or requirement for the invasive injection of exogenous contrast agents. Here, we developed a novel multimodal imaging system for high-speed, high-resolution retinal imaging of larger animals, such as rabbits. The system integrates three state-of-the-art imaging modalities, including photoacoustic microscopy (PAM), optical coherence tomography (OCT), and fluorescence microscopy (FM). In vivo experimental results of rabbit eyes show that the PAM is able to visualize laser-induced retinal burns and distinguish individual eye blood vessels using a laser exposure dose of ~80 nJ, which is well below the American National Standards Institute (ANSI) safety limit 160 nJ. The OCT can discern different retinal layers and visualize laser burns and choroidal detachments. The novel multi-modal imaging platform holds great promise in ophthalmic imaging.

(Some) current concepts in antibacterial drug discovery

The rise of multidrug resistance in bacteria rendering pathogens unresponsive to many clinical drugs is widely acknowledged and considered a critical global healthcare issue. There is broad consensus that novel antibacterial chemotherapeutic options are extremely urgently needed. However, the development pipeline of new antibacterial drug lead structures is poorly filled and not commensurate with the scale of the problem since the pharmaceutical industry has shown reduced interest in antibiotic development in the past decades due to high economic risks and low profit expectations. Therefore, academic research institutions have a special responsibility in finding novel treatment options for the future. In this mini review, we want to provide a broad overview of the different approaches and concepts that are currently pursued in this research field.

Novel Photoacoustic Microscopy and Optical Coherence Tomography Dual-modality Chorioretinal Imaging in Living Rabbit Eyes

Photoacoustic ocular imaging is an emerging ophthalmic imaging technology that can noninvasively visualize ocular tissue by converting light energy into sound waves and is currently under intensive investigation. However, most reported work to date is focused on the imaging of the posterior segment of the eyes of small animals, such as rats and mice, which poses challenges for clinical human translation due to small eyeball sizes. This manuscript describes a novel photoacoustic microscopy (PAM) and optical coherence tomography (OCT) dual-modality system for posterior segment imaging of the eyes of larger animals, such as rabbits. The system configuration, system alignment, animal preparation, and dual-modality experimental protocols for in vivo, noninvasive, label-free chorioretinal imaging in rabbits are detailed. The effectiveness of the method is demonstrated through representative experimental results, including retinal and choroidal vasculature obtained by the PAM and OCT. This manuscript provides a practical guide to reproducing the imaging results in rabbits and advancing photoacoustic ocular imaging in larger animals.

Antioxidant activity of omega-3 derivatives and their delivery via nanocages and nanocones: DFT and experimental in vivo investigation

The antioxidant properties of omega-3 were investigated via experimental in vivo and theoretical methods. For experimental evaluation, oxidative stress was induced by 30 min bilateral renal ischemia and 24 h of reperfusion in male Sprague Dawley rats. The oxidative stress was evaluated through measuring malondialdehyde (MDA) and ferric reducing/antioxidant power (FRAP) levels in renal tissue. In theoretical methods, the reaction enthalpies of antioxidant mechanisms of omega-3 were calculated and the effects of NHMe, OMe, OH, Cl, and Me substituents on its antioxidant activity were investigated. Moreover, the omega-3 delivery potential by carbon and boron nitride nanocages and naocones were evaluated. The experimental results showed that omega-3 administration decreases MDA and increases FRAP levels after their changes by ischemia/reperfusion. Theoretical results indicated that NHMe and OMe substituents can significantly improve the antioxidant activity of omega-3. Also, boron nitride nanocone (BNNC) has higher |∆E_ad| values, so it has higher potential for omega-3 delivery. Taken together, the new findings presented here indicate that omega-3 has anti-oxidative properties and NHMe and OMe substituents can improve its antioxidant activity. Moreover, adsorption of omega-3 on the surface of the studied nanostructures was exothermic, and BNNC with higher |∆Ead| values has higher potential for omega-3 delivery. Graphical abstract The interaction and adsorption of BNNC with omega-3 is exothermic and experimentally possible from the energetic viewpoint, so the BNNC with higher |∆E_ad| and |∆G_ad| values has higher potential for omega-3 delivery.

In Vivo Imaging-Guided Photothermal/Photoacoustic Synergistic Therapy with Bioorthogonal Metabolic Glycoengineering-Activated Tumor Targeting Nanoparticles

Developing multifunctional phototheranostics with nanoplatforms offers promising potential for effective eradication of malignant solid tumors. In this study, we develop a multifunctional phototheranostic by combining photothermal therapy (PTT) and photoacoustic therapy (PAT) based on a tumor-targeting nanoagent (DBCO-ZnPc-LP). The nanoagent DBCO-ZnPc-LP was facilely prepared by self-assembling of a single lipophilic near-infrared (NIR) dye zinc(II)-phthalocyanine (ZnPc) with a lipid-poly(ethylene glycol) (LP) and following modified further with dibenzyl cyclootyne (DBCO) for introducing the two-step chemical tumor-targeting strategy based on metabolic glycoengineering and click chemistry. The as-prepared DBCO-ZnPc-LP could not only convert NIR light into heat for effective thermal ablation but also induce a thermal-enhanced ultrasound shockwave boost to trigger substantially localized mechanical damage, achieving synergistic antitumor effect both in vitro and in vivo. Moreover, DBCO-ZnPc-LP can be efficiently delivered into tumor cells and solid tumors after being injected intravenously via the two-step tumor-targeting strategy. By integrating the targeting strategy, photoacoustic imaging, and the synergistic interaction between PTT and PAT, a solid tumor could be accurately positioned and thoroughly eradicated in vivo. Therefore, this multifunctional phototheranostic is believed to play an important role in future oncotherapy by the enhanced synergistic effect of PTT and PAT under the guidance of photoacoustic imaging.

Cellular Uptake and Intra-Organ Biodistribution of Functionalized Silica-Coated Gold Nanorods

PURPOSE

To develop a new nanobiosystem based on folate-functionalized silica-coated gold nanorods and to investigate its cellular uptake and intra-organ biodistribution in vitro and in vivo.

PROCEDURES

Ellipsoidal silica-coated gold nanorods (GNRs@SIO2) were prepared by seeded growth method using silicon dioxide (SIO2) as the shell material. Rhodamine-labeled GNRs@SiO2-folic acid (FA) were obtained by reacting the amino group located on GNRs@SiO2-FA with rhodamine isothiocyanate. The characteristics of the prepared GNRs@SiO2-FA were studied using transmission electron microscopy (TEM) and UV spectra. The 3-[4, 5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium bromide (MTT) colorimetric method was used to assess the biocompatibility of GNRs@SiO2-FA, and their uptake into cells was observed using TEM. In vivo experiments of cellular uptake and study of the intra-organ biodistribution of GNRs@SiO2-FA were detected using intrinsic two-photon luminescence.

RESULTS

Analysis of UV spectra confirmed the successfu1 preparation of GNRs@SiO2-FA. Results of the MTT assay demonstrated that surface modification of GNRs@SiO2-FA resulted in excellent biocompatibility. TEM examination revealed that GNRs@SiO2-FA entered the cells via endocytosis, which could connect to cancer cells with high folic acid expression. We found that GNRs exhibit bright luminescence and could be visualized in vivo by direct imaging of these particles within the tissue. Additionally, GNRs@SiO2-FA could specifically bind to tumor cells. GNRs@SiO2-FA entered tumor cells within 24 h and had a heterogeneous distribution with higher accumulation at the tumor cytoplasm.

CONCLUSION

GNRs@SiO2-FA can bind to cells and were found to be internalized by targeted folate receptor-expressing cells via a ligand-receptor-mediated endocytosis pathway, which is very useful in diagnosing diseases as well as in treating neoplasm with I-125 particles.

Mitochondria-targeting Au nanoclusters enhance radiosensitivity of cancer cells

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

Thermoacoustic Imaging and Therapy Guidance based on Ultra-short Pulsed Microwave Pumped Thermoelastic Effect Induced with Superparamagnetic Iron Oxide Nanoparticles

Multifunctional nanoparticle-mediated imaging and therapeutic techniques are promising modalities for accurate localization and targeted treatment of cancer in clinical settings. Thermoacoustic (TA) imaging is highly sensitive to detect the distribution of water, ions or specific nanoprobes and provides excellent resolution, good contrast and superior tissue penetrability. TA therapy is a potential non-invasive approach for the treatment of deep-seated tumors. In this study, human serum albumin (HSA)-functionalized superparamagnetic iron oxide nanoparticle (HSA-SPIO) is used as a multifunctional nanoprobe with clinical application potential for MRI, TA imaging and treatment of tumor. In addition to be a MRI contrast agent for tumor localization, HSA-SPIO can absorb pulsed microwave energy and transform it into shockwave via the thermoelastic effect. Thereby, the reconstructed TA image by detecting TA signal is expected to be a sensitive and accurate representation of the HSA-SPIO accumulation in tumor. More importantly, owing to the selective retention of HSA-SPIO in tumor tissues and strong TA shockwave at the cellular level, HSA-SPIO induced TA effect under microwave-pulse radiation can be used to highly-efficiently kill cancer cells and inhibit tumor growth. Furthermore, ultra-short pulsed microwave with high excitation efficiency and deep penetrability in biological tissues makes TA therapy a highly-efficient anti-tumor modality on the versatile platform. Overall, HSA-SPIO mediated MRI and TA imaging would offer more comprehensive diagnostic information and enable dynamic visualization of nanoagents in the tumorous tissue thereby tumor-targeted therapy.

Recent advances in carbon based nanosystems for cancer theranostics

This review deals with four different types of carbon allotrope based nanosystems and summarizes the results of recent studies that are likely to have applications in cancer theranostics. We discuss the applications of these nanosystems for cancer imaging, drug delivery, hyperthermia, and PDT/TA/PA.

Dispersed single wall carbon nanotubes do not impact mitochondria structure or function, but technical issues during analysis could yield incorrect results

Mitochondria, which generate cellular energy, are not influenced by purified carbon nanotubes. Many traditional biological assays to determine mitochondria function give false results because of nanotube surface activity and optical interference.

Hydrophilic graphene oxide/bismuth selenide nanocomposites for CT imaging, photoacoustic imaging, and photothermal therapy

GO/Bi₂Se₃/PVP nanocomposites fabricated by a one-pot solvothermal method show good performance in CT/photoacoustic imaging and photothermal therapy.

A Highly Photostable Hyperbranched Polyglycerol-Based NIR Fluorescence Nanoplatform for Mitochondria-Specific Cell Imaging

Considering the critical role of mitochondria in the life and death of cells, non-invasive long-term tracking of mitochondria has attracted considerable interest. However, a high-performance mitochondria-specific labeling probe with high photostability is still lacking. Herein a highly photostable hyperbranched polyglycerol (hPG)-based near-infrared (NIR) quantum dots (QDs) nanoplatform is reported for mitochondria-specific cell imaging. Comprising NIR Zn-Cu-In-S/ZnS QDs as extremely photostable fluorescent labels and alkyl chain (C12 )/triphenylphosphonium (TPP)-functionalized hPG derivatives as protective shell, the tailored QDs@hPG-C12 /TPP nanoprobe with a hydrodynamic diameter of about 65 nm exhibits NIR fluorescence, excellent biocompatibility, good stability, and mitochondria-targeted ability. Cell uptake experiments demonstrate that QDs@hPG-C12 /TPP displays a significantly enhanced uptake in HeLa cells compared to nontargeted QDs@hPG-C12 . Further co-localization study indicates that the probe selectively targets mitochondria. Importantly, compared with commercial deep-red mitochondria dyes, QDs@hPG-C12 /TPP possesses superior photostability under continuous laser irradiation, indicating great potential for long-term mitochondria labeling and tracking. Moreover, drug-loaded QDs@hPG-C12 /TPP display an enhanced tumor cell killing efficacy compared to nontargeted drugs. This work could open the door to the construction of organelle-targeted multifunctional nanoplatforms for precise diagnosis and high-efficient tumor therapy.

Novel targets for paclitaxel nano formulations: Hopes and hypes in triple negative breast cancer

Triple negative breast cancer is defined as one of the utmost prevailing breast cancers worldwide, possessing an inadequate prognosis and treatment option limited to chemotherapy and radiotherapy, creating a challenge for researchers as far as developing a specific targeted therapy is concerned. The past research era has shown several promising outcomes for TNBC such as nano-formulations of the chemotherapeutic agents already used for the management of the malignant tumor. Taking a glance at paclitaxel nano formulations, it has been proven beneficial in several researches in the past decade; nevertheless its solubility is often a challenge to scientists in achieving success. We have henceforth discussed the basic heterogeneity of triple negative breast cancer along with the current management options as well as a brief outlook on pros and cons of paclitaxel, known as the most widely used chemotherapeutic agent for the treatment of the disease. We further analyzed the need of nanotechnology pertaining to the problems encountered with the current paclitaxel formulations available discussing the strategic progress in various nano-formulations till date taking into account the basic research strategies required in terms of solubility, permeability, physicochemical properties, active and passive targeting. A thorough review in recent advances in active targeting for TNBC was carried out whereby the various ligands which are at present finding its way into TNBC research such as hyaluronic acid, folic acid, transferrin, etc. were discussed. These ligands have specific receptor affinity to TNBC tumor cells hence can be beneficial for novel drug targeting approaches. Conversely, there are currently several novel strategies in the research pipeline whose targeting ligands have not yet been studied. Therefore, we reviewed upon the numerous novel receptor targets along with the respective nano-formulation aspects which have not yet been fully researched upon and could be exemplified as outstanding target strategies for TNBC which is currently an urgent requirement.

A graphene oxide based smart drug delivery system for tumor mitochondria-targeting photodynamic therapy

Subcellular organelles play critical roles in cell survival. In this work, a novel photodynamic therapy (PDT) drug delivery and phototoxicity on/off nano-system based on graphene oxide (NGO) as the carrier is developed to implement subcellular targeting and attacking. To construct the nanodrug (PPa-NGO-mAb), NGO is modified with the integrin αvβ3 monoclonal antibody (mAb) for tumor targeting. Pyropheophorbide-a (PPa) conjugated with polyethylene-glycol is used to cover the surface of the NGO to induce phototoxicity. Polyethylene-glycol phospholipid is loaded to enhance water solubility. The results show that the phototoxicity of PPa on NGO can be switched on and off in organic and aqueous environments, respectively. The PPa-NGO-mAb assembly is able to effectively target the αvβ3-positive tumor cells with surface ligand and receptor recognition; once endocytosized by the cells, they are observed escaping from lysosomes and subsequently transferring to the mitochondria. In the mitochondria, the 'on' state PPa-NGO-mAb performs its effective phototoxicity to kill cells. The biological and physical dual selections and on/off control of PPa-NGO-mAb significantly enhance mitochondria-mediated apoptosis of PDT. This smart system offers a potential alternative to drug delivery systems for cancer therapy.

Chemo/Photoacoustic Dual Therapy with mRNA-Triggered DOX Release and Photoinduced Shockwave Based on a DNA-Gold Nanoplatform

A multifunctional nanoparticle based on gold nanorod (GNR), utilizing mRNA triggered chemo-drug release and near-infrared photoacoustic effect, is developed for a combined chemo-photoacoustic therapy. The constructed nanoparticle (GNR-DNA/FA:DOX) comprises three functional components: (i) GNR as the drug delivery platform and photoacoustic effect enhancer; (ii) toehold-possessed DNA dressed on the GNR to load doxorubicin (DOX) to implement a tumor cell specific chemotherapy; and (iii) folate acid (FA) modified on GNR to guide the nanoparticle to target tumor cells. The results show that, upon an effective and specific delivery of the nanoparticles to the tumor cells with overexpressed folate receptors, the cytotoxic DOX loaded on the GNR-DNA nanoplatform can be released through DNA displacement reaction in melanoma-associated antigen gene mRNA expressed cells. With 808 nm pulse laser irradiation, the photoacoustic effect of the GNR leads to a direct physical damage to the cells. The combined treatment of the two modalities can effectively destroy tumor cells and eradicate the tumors with two distinctively different and supplementing mechanisms. With the nanoparticle, photoacoustic imaging is successfully performed in situ to monitor the drug distribution and tumor morphology for therapeutical guidance. With further in-depth investigation, the proposed nanoparticle may provide an effective and safe alternative cancer treatment modality.

Imaging-guided photoacoustic drug release and synergistic chemo-photoacoustic therapy with paclitaxel-containing nanoparticles

Here, a novel triggered drug release modality was developed for oncotherapy. Paclitaxel (PTX), perfluorohexane (PFH) and gold nanorods (AuNRs) loaded nanoparticles (PTX-PAnP) were synthesized. Folic acid (FA) conjugated PTX-PAnP (PTX-PAnP-FA) could be selectively taken into folate receptor-overexpressed tumor cells. Upon pulsed laser irradiation, the PTX-PAnP-FA could be rapidly destructed because of the PFH vaporization, resulting in fast drug release, which induced apoptosis of cancer cells efficiently. Stimulated fragmentation of the PTX-PAnP-FA nanoparticles can facilitate multiple mechanisms such as bubble implosion, shockwave generation, and sonoporation that further enhance the therapeutic efficiency. The in vivo therapy study further confirmed this new approach resulted in efficient tumor suppression. The results demonstrate a unique drug release mechanism based on photoacoustic effect. It provides an all-in-one platform for photoacoustic image-guided drug release and synergistic chemo-photoacoustic therapy.

Nanoparticle Probes for Structural and Functional Photoacoustic Molecular Tomography

Nowadays, nanoparticle probes have received extensive attention largely due to its potential biomedical applications in structural, functional, and molecular imaging. In addition, photoacoustic tomography (PAT), a method based on the photoacoustic effect, is widely recognized as a robust modality to evaluate the structure and function of biological tissues with high optical contrast and high acoustic resolution. The combination of PAT with nanoparticle probes holds promises for detecting and imaging diseased tissues or monitoring their treatments with high sensitivity. This review will introduce the recent advances in the emerging field of nanoparticle probes and their preclinical applications in PAT, as well as relevant perspectives on future development.

Targeted delivery of doxorubicin to mitochondria using mesoporous silica nanoparticle nanocarriers

A lot of investigations have been conducted using mesoporous silica nanoparticles (MSNPs) functionalized with different targeting ligands in order to deliver various hydrophobic and hydrophilic drugs to targeted cancer cells. However, the utilization of MSNPs to deliver drug molecules to targeted subcellular organelles has been rarely reported. In this work, we applied targeting ligand-conjugated MSNPs with an average diameter of 80 nm to deliver the anticancer drug doxorubicin (DOX) to mitochondria. Triphenoylphosphonium (TPP) was functionalized on MSNPs as a mitochondria targeting ligand. Mitochondria targeting efficiency was demonstrated in HeLa cells by a co-localization study of mitochondria and functionalized MSNPs as well as by fluorescence analysis in isolated mitochondria. In addition, enhanced cancer cell killing efficacy was achieved when using DOX-loaded and TPP-functionalized MSNPs for mitochondria-targeted delivery. Lowered adenosine triphosphate (ATP) production and decreased mitochondrial membrane potential were observed, demonstrating the mitochondria dysfunction caused by delivered DOX. The positive results indicate promising application potential of MSNPs in targeted subcellular drug delivery.

Microwave pumped high-efficient thermoacoustic tumor therapy with single wall carbon nanotubes

The ultra-short pulse microwave could excite to the strong thermoacoustic (TA) shock wave and deeply penetrate in the biological tissues. Based on this, we developed a novel deep-seated tumor therapy modality with mitochondria-targeting single wall carbon nanotubes (SWNTs) as microwave absorbing agents, which act efficiently to convert ultra-short microwave energy into TA shock wave and selectively destroy the targeted mitochondria, thereby inducing apoptosis in cancer cells. After the treatment of SWNTs (40 μg/mL) and ultra-short microwave (40 Hz, 1 min), 77.5% of cancer cells were killed and the vast majority were caused by apoptosis that initiates from mitochondrial damage. The orthotopic liver cancer mice were established as deep-seated tumor model to investigate the anti-tumor effect of mitochondria-targeting TA therapy. The results suggested that TA therapy could effectively inhibit the tumor growth without any observable side effects, while it was difficult to achieve with photothermal or photoacoustic therapy. These discoveries implied the potential application of TA therapy in deep-seated tumor models and should be further tested for development into a promising therapeutic modality for cancer treatment.

Photoacoustic "nanobombs" fight against undesirable vesicular compartmentalization of anticancer drugs

Undesirable intracellular vesicular compartmentalization of anticancer drugs in cancer cells is a common cause of chemoresistance. Strategies aimed at circumventing this problem may improve chemotherapeutic efficacy. We report a novel photophysical strategy for controlled-disruption of vesicular sequestration of the anticancer drug doxorubicin (DOX). Single-walled carbon nanotubes (SWCNTs), modified with folate, were trapped in acidic vesicles after entering lung cancer cells. Upon irradiation by near-infrared pulsed laser, these vesicles were massively broken by the resulting photoacoustic shockwave, and the vesicle-sequestered contents were released, leading to redistribution of DOX from cytoplasm to the target-containing nucleus. Redistribution resulted in 12-fold decrease of the EC50 of DOX in lung cancer cells, and enhanced antitumor efficacy of low-dose DOX in tumor-bearing mice. Side effects were not observed. These findings provide insights of using nanotechnology to improve cancer chemotherapy, i.e. not only for drug delivery, but also for overcoming intracellular drug-transport hurdles.

Fluorescence Quenching Nanoprobes Dedicated to In Vivo Photoacoustic Imaging and High-Efficient Tumor Therapy in Deep-Seated Tissue

Photoacoustic imaging (PAI) and photoacoustic (PA) therapy have promising applications for treating tumors. It is known that the utilization of high-absorption-coefficient probes can selectively enhance the PAI target contrast and PA tumor therapy efficiency in deep-seated tissue. Here, the design of a probe with the highest availability of optical-thermo conversion by using graphene oxide (GO) and dyes via π-π stacking interactions is reported. The GO serves as a base material for loading dyes and quenching dye fluorescence via fluorescence resonance energy transfer (FRET), with the one purpose of maximum of PA efficiency. Experiments verify that the designed fluorescence quenching nanoprobes can produce stronger PA signals than the sum of the separate signals generated in the dye and the GO. Potential applications of the fluorescence quenching nanoprobes are demonstrated, dedicating to enhance PA contrast of targets in deep-seated tissues and tumors in living mice. PA therapy efficiency both in vitro and in vivo by using the fluorescence quenching nanoprobes is found to be higher than with the commonly used PA therapy agents. Taken together, quenching dye fluorescence via FRET will provide a valid means for developing high-efficiency PA probes. Fluorescence quenching nanoprobes are likely to become a promising candidate for deep-seated tumor imaging and therapy.

Dual-targeting nanosystem for enhancing photodynamic therapy efficiency

Photodynamic therapy (PDT) has been recognized as a valuable treatment option for localized cancers. Herein, we demonstrate a cellular and subcellular targeted strategy to facilitate PDT efficacy. The PDT system was fabricated by incorporating a cationic porphyrin derivative (MitoTPP) onto the polyethylene glycol (PEG)-functionalized and folic acid-modified nanographene oxide (NGO). For this PDT system, NGO serves as the carrier for MitoTPP as well as the quencher for MitoTPP's fluorescence and singlet oxygen ((1)O2) generation. Attaching a hydrophobic cation to the photosensitizer ensures its release from NGO at lower pH values as well as its mitochondria-targeting capability. Laser confocal microscope experiments demonstrate that this dual-targeted nanosystem could preferably enter the cancer cells overexpressed with folate receptor, and release its cargo MitoTPP, which subsequently accumulates in mitochondria. Upon light irradiation, the released MitoTPP molecules generate singlet oxygen and cause oxidant damage to the mitochondria. Cell viability assays suggest that the dual-targeted nanohybrids exhibit much higher cytotoxicity toward the FR-positive cells.