Multifunctional Polypyrrole-Coated Mesoporous TiO2 Nanocomposites for Photothermal, Sonodynamic, and Chemotherapeutic Treatments and Dual-Modal Ultrasound/Photoacoustic Imaging of Tumors

The Advancing Role of Nanocomposites in Cancer Diagnosis and Treatment

The relentless pursuit of effective cancer diagnosis and treatment strategies has led to the rapidly expanding field of nanotechnology, with a specific focus on nanocomposites. Nanocomposites, a combination of nanomaterials with diverse properties, have emerged as versatile tools in oncology, offering multifunctional platforms for targeted delivery, imaging, and therapeutic interventions. Nanocomposites exhibit great potential for early detection and accurate imaging in cancer diagnosis. Integrating various imaging modalities, such as magnetic resonance imaging (MRI), computed tomography (CT), and fluorescence imaging, into nanocomposites enables the development of contrast agents with enhanced sensitivity and specificity. Moreover, functionalizing nanocomposites with targeting ligands ensures selective accumulation in tumor tissues, facilitating precise imaging and diagnostic accuracy. On the therapeutic front, nanocomposites have revolutionized cancer treatment by overcoming traditional challenges associated with drug delivery. The controlled release of therapeutic agents from nanocomposite carriers enhances drug bioavailability, reduces systemic toxicity, and improves overall treatment efficacy. Additionally, the integration of stimuli-responsive components within nanocomposites enables site-specific drug release triggered by the unique microenvironment of the tumor. Despite the remarkable progress in the field, challenges such as biocompatibility, scalability, and long-term safety profiles remain. This article provides a comprehensive overview of recent developments, challenges, and prospects, emphasizing the transformative potential of nanocomposites in revolutionizing the landscape of cancer diagnostics and therapeutics. In Conclusion, integrating nanocomposites in cancer diagnosis and treatment heralds a new era for precision medicine.

A Study of Sonodynamic Therapy of Melanoma C540 Cells in Vitro by Titania/Gold Nanoparticles

Background

Sonodynamic Therapy (SDT), a safe and non-invasive strategy in tumor therapy, is in development using novel sono-sensitizers, activated by low-intensity ultrasound radiation. SDT mainly progresses through Reactive Oxygen Species (ROS) generation followed by cell annihilation.

Objective

The current study aimed to investigate the effect of ultrasound therapy with titania/gold nanoparticles (NPs) on melanoma cancer.

Material and Methods

In this experimental study, Titania/gold NPs (TGNPs) were synthesized, and their activity was investigated in sonodynamic therapy of a melanoma cancer cell line (C540). SDT was performed at 1.0 W cm-2 and 1.0 MHz for one minute.

Results

The synthesized NPs that comprised gold NPs of <10 nm into titania NPs of <20 nm showed great stability and cytocompatibility. While TGNPs were biocompatible, a remarkable rate of cell ablation was observed upon ultrasound irradiation due to ROS generation.

Conclusion

The SDT using TGNPs can be introduced as an alternative and low-cost treatment method for melanoma malignancy.

Gold-Crowned Bismuth-Based Nanocomposites for Sonodynamic, Photothermal, and Chemotherapeutic Cancer Therapy

Conventional inorganic semiconductor nanoparticles have emerged as photothermal agents in photothermal therapy and as sonosensitizers in sonodynamic therapy. However, their weak drug-loading capabilities and the deficient techniques for multifunctional inorganic nanoparticles limit their applications. A bismuth-based gold-crowned nanocomposite (BACN) was rationally designed and successfully synthesized and could then be used to prepare nanoplatforms with excellent biocompatibilities for synergistic therapy and real-time imaging. Because of the constituent gold nanoparticles and pyridine, the nanoplatforms functioned as drug delivery vehicles, ultrasonically activated sonosensitizers, and photothermal agents. The BACNs exhibited excellent photothermal conversion efficiency (79.1%) in the second near-infrared biowindow (1064 nm). Cellular and mouse experiments demonstrated that under laser and ultrasound irradiation bufalin-loaded BACNs significantly reduced cancer cell counts and completely eradicated tumors, along with great therapeutic biosafety and no discernible recurrence. Additionally, BACNs were also used as contrast agents in computed tomography-photoacoustic imaging. The versatile BACN nanoplatform with multitreatment effects and trimodal imaging properties shows immense potential as an antitumor nanotherapeutic system.

Nanotechnology-Based Drug Delivery Systems for Honokiol: Enhancing Therapeutic Potential and Overcoming Limitations

Honokiol (HNK) is a small-molecule polyphenol that has garnered considerable attention due to its diverse pharmacological properties, including antitumor, anti-inflammatory, anti-bacterial, and anti-obesity effects. However, its clinical application is restricted by challenges such as low solubility, poor bioavailability, and rapid metabolism. To overcome these limitations, researchers have developed a variety of nano-formulations for HNK delivery. These nano-formulations offer advantages such as enhanced solubility, improved bioavailability, extended circulation time, and targeted drug delivery. However, existing reviews of HNK primarily focus on its clinical and pharmacological features, leaving a gap in the comprehensive evaluation of HNK delivery systems based on nanotechnology. This paper aims to bridge this gap by comprehensively reviewing different types of nanomaterials used for HNK delivery over the past 15 years. These materials encompass vesicle delivery systems, nanoparticles, polymer micelles, nanogels, and various other nanocarriers. The paper details various HNK nano-delivery strategies and summarizes their latest applications, development prospects, and future challenges. To compile this review, we conducted an extensive search using keywords such as "honokiol", "nanotechnology", and "drug delivery system" on reputable databases, including PubMed, Scopus, and Web of Science, covering the period from 2008 to 2023. Through this search, we identified and selected approximately 90 articles that met our specific criteria.

Precise antibacterial therapeutics based on stimuli-responsive nanomaterials

Bacterial infection refers to the process in which bacteria invade, grow, reproduce, and interact with the body, ultimately causing a series of pathological changes. Nowadays, bacterial infection remains a significant public health issue, posing a huge threat to human health and a serious financial burden. In the post-antibiotic era, traditional antibiotics are prone to inducing bacterial resistance and difficulty in removing bacterial biofilm. In recent years, antibacterial therapy based on nanomaterials has developed rapidly. Compared with traditional antibiotics, nanomaterials effectively remove bacterial biofilms and rarely result in bacterial resistance. However, due to nanomaterials' strong permeability and effectiveness, they will easily cause cytotoxicity when they are not controlled. In addition, the antibacterial effect of non-responsive nanomaterials cannot be perfectly exerted since the drug release property or other antibacterial effects of these nano-materials are not be positively correlated with the intensity of bacterial infection. Stimuli-responsive antibacterial nanomaterials are a more advanced and intelligent class of nano drugs, which are controlled by exogenous stimuli and microenvironmental stimuli to change the dosage and intensity of treatment. The excellent spatiotemporal controllability enables stimuli-responsive nanomaterials to treat bacterial infections precisely. In this review, we first elaborate on the design principles of various stimuli-responsive antibacterial nanomaterials. Then, we analyze and summarizes the antibacterial properties, advantages and shortcomings of different applied anti-bacterial strategies based on stimuli-responsive nanomaterials. Finally, we propose the challenges of employing stimuli-responsive nanomaterials and corresponding potential solutions.

Ultrasound Sonosensitizers for Tumor Sonodynamic Therapy and Imaging: A New Direction with Clinical Translation

With the rapid development of sonodynamic therapy (SDT), sonosensitizers have evolved from traditional treatments to comprehensive diagnostics and therapies. Sonosensitizers play a crucial role in the integration of ultrasound imaging (USI), X-ray computed tomography (CT), and magnetic resonance imaging (MRI) diagnostics while also playing a therapeutic role. This review was based on recent articles on multifunctional sonosensitizers that were used in SDT for the treatment of cancer and have the potential for clinical USI, CT, and MRI applications. Next, some of the shortcomings of the clinical examination and the results of sonosensitizers in animal imaging were described. Finally, this paper attempted to inform the future development of sonosensitizers in the field of integrative diagnostics and therapeutics and to point out current problems and prospects for their application.

Sonocatalytic Optimization of Titanium-Based Therapeutic Nanomedicine

Recent considerable technological advances in ultrasound-based treatment modality provides a magnificent prospect for scientific communities to conquer the related diseases, which is featured with remarkable tissue penetration, non-invasive and non-thermal characteristics. As one of the critical elements that influences treatment outcomes, titanium (Ti)-based sonosensitizers with distinct physicochemical properties and exceptional sonodynamic efficiency have been applied extensively in the field of nanomedical applications. To date, a myriad of methodologies has been designed to manipulate the sonodynamic performance of titanium-involved nanomedicine and further enhance the productivity of reactive oxygen species for disease treatments. In this comprehensive review, the sonocatalytic optimization of diversified Ti-based nanoplatforms, including defect engineering, plasmon resonance modulation, heterojunction, modulating tumor microenvironment, as well as the development of synergistic therapeutic modalities is mainly focused. The state-of-the-art Ti-based nanoplatforms ranging from preparation process to the extensive medical applications are summarized and highlighted, with the goal of elaborating on future research prospects and providing a perspective on the bench-to-beside translation of these sonocatalytic optimization tactics. Furthermore, to spur further technological advancements in nanomedicine, the difficulties currently faced and the direction of sonocatalytic optimization of Ti-based therapeutic nanomedicine are proposed and outlooked.

Nanomaterials for photothermal cancer therapy

Cancer has emerged as a pressing global public health issue, and improving the effectiveness of cancer treatment remains one of the foremost challenges of modern medicine. The primary clinical methods of treating cancer, including surgery, chemotherapy and radiotherapy, inevitably result in some adverse effects on the body. However, the advent of photothermal therapy offers an alternative route for cancer treatment. Photothermal therapy relies on photothermal agents with photothermal conversion capability to eliminate tumors at high temperatures, which offers advantages of high precision and low toxicity. As nanomaterials increasingly play a pivotal role in tumor prevention and treatment, nanomaterial-based photothermal therapy has gained significant attention owing to its superior photothermal properties and tumor-killing abilities. In this review, we briefly summarize and introduce the applications of common organic photothermal conversion materials (e.g., cyanine-based nanomaterials, porphyrin-based nanomaterials, polymer-based nanomaterials, etc.) and inorganic photothermal conversion materials (e.g., noble metal nanomaterials, carbon-based nanomaterials, etc.) in tumor photothermal therapy in recent years. Finally, the problems of photothermal nanomaterials in antitumour therapy applications are discussed. It is believed that nanomaterial-based photothermal therapy will have good application prospects in tumor treatment in the future.

Fractionated Sonodynamic Therapy Using Gold@Poly(ortho-aminophenol) Nanoparticles and Multistep Low-Intensity Ultrasound Irradiation to Treat Melanoma Cancer: In Vitro and In Vivo Studies

OBJECTIVE

Cancer treatment using ultrasound irradiation with low intensities along with a sonosensitizer has been found to have significant advantages, such as high penetration depth in tissues, non-invasive therapeutic character, minor side effects, good patient adherence and preferential tumor area treatment. In the present study, gold nanoparticles covered by poly(ortho-aminophenol) (Au@POAP NPs) were synthesized and characterized as a new sonosensitizer.

METHODS

We investigated Au@POAP NPs efficacy on fractionated ultrasound irradiation for treatment of melanoma cancer in vitro as well as in vivo.

DISCUSSION

In vitro examinations revealed that although Au@POAP NPs (with a mean size of 9.8 nm) alone represented concentration-dependent cytotoxicity against the B16/F10 cell line, multistep ultrasound irradiation (1 MHz frequency, 1.0 W/cm² intensity, 60 s irradiation time) of the cells in the attendance of Au@POAP NPs led to efficient cell sonodynamic therapy (SDT) and death. Histological analyses revealed that in vivo fractionated SDT toward melanoma tumors of male balb/c mice led to no residual viable tumor cell after 10 d.

CONCLUSION

A deep sonosensitizing effectiveness of Au@POAP NPs on fractionated low-intensity ultrasound irradiation was attained with the main mechanism of tumor cell eradication of promotion of apoptosis or necrosis through dramatically increased reactive oxygen species levels.

Surface modification of TiO2 nanoparticles with organic molecules and their biological applications

In recent years, titanium(IV) dioxide nanoparticles (TiO₂NPs) have shown promising potential in various biological applications such as antimicrobials, drug delivery, photodynamic therapy, biosensors, and tissue engineering. For employing TiO₂NPs in these fields, their nanosurface must be coated or conjugated with organic and/or inorganic agents. This modification can improve their stability, photochemical properties, biocompatibility, and even surface area for further conjugation with other molecules such as drugs, targeting molecules, polymers, etc. This review describes the organic-based modification of TiO₂NPs and their potential applications in the mentioned biological fields. In the first part of this review, around 75 recent publications (2017-2022) are mentioned on the common TiO₂NP modifiers including organosilanes, polymers, small molecules, and hydrogels, which improve the photochemical features of TiO₂NPs. In the second part of this review, we presented 149 recent papers (2020-2022) about the use of modified TiO₂NPs in biological applications, in which specific bioactive modifiers are introduced in this part with their advantages. In this review, the following information is presented: (1) the common organic modifiers for TiO₂NPs, (2) biologically important modifiers and their benefits, and (3) recent publications on biological studies on the modified TiO₂NPs with their achievements. This review shows the paramount significance of the organic-based modification of TiO₂NPs to enhance their biological effectiveness, paving the way toward the development of advanced TiO₂-based nanomaterials in nanomedicine.

Metal-Organic Frameworks (MOF)-Assisted Sonodynamic Therapy in Anticancer Applications

Sonodynamic therapy (SDT) has emerged as a promising therapeutic modality for anticancer treatments and is becoming a cutting-edge interdisciplinary research field. This review starts with the latest developments of SDT and provides a brief comprehensive discussion on ultrasonic cavitation, sonodynamic effect, and sonosensitizers in order to popularize the basic principles and probable mechanisms of SDT. Then the recent progress of MOF-based sonosensitizers is overviewed, and the preparation methods and properties (e.g., morphology, structure, and size) of products are presented in a fundamental perspective. More importantly, many deep observations and understanding toward MOF-assisted SDT strategies were described in anticancer applications, aiming to highlight the advantages and improvements of MOF-augmented SDT and synergistic therapies. Last but not least, the review also pointed out the probable challenges and technological potential of MOF-assisted SDT for the future advance. In all, the discussions and summaries of MOF-based sonosensitizers and SDT strategies will promote the fast development of anticancer nanodrugs and biotechnologies.

Titanium-Based Nanoarchitectures for Sonodynamic Therapy-Involved Multimodal Treatments

Sonodynamic therapy (SDT) has considerably revolutionized the healthcare sector as a viable noninvasive therapeutic procedure. It employs a combination of low-intensity ultrasound and chemical entities, known as a sonosensitizer, to produce cytotoxic reactive oxygen species (ROS) for cancer and antimicrobial therapies. With nanotechnology, several unique nanoplatforms are introduced as a sonosensitizers, including, titanium-based nanomaterials, thanks to their high biocompatibility, catalytic efficiency, and customizable physicochemical features. Additionally, developing titanium-based sonosensitizers facilitates the integration of SDT with other treatment modalities (for example, chemotherapy, chemodynamic therapy, photodynamic therapy, photothermal therapy, and immunotherapy), hence increasing overall therapeutic results. This review summarizes the most recent developments in cancer therapy and tissue engineering using titanium nanoplatforms mediated SDT. The synthesis strategies and biosafety aspects of Titanium-based nanoplatforms for SDT are also discussed. Finally, various challenges and prospects for its further development and potential clinical translation are highlighted.

Recent Advances in Contrast-Enhanced Photoacoustic Imaging: Overcoming the Physical and Practical Challenges

For decades now, photoacoustic imaging (PAI) has been investigated to realize its potential as a niche biomedical imaging modality. Despite its highly desirable optical contrast and ultrasonic spatiotemporal resolution, PAI is challenged by such physical limitations as a low signal-to-noise ratio (SNR), diminished image contrast due to strong optical attenuation, and a lower-bound on spatial resolution in deep tissue. In addition, contrast-enhanced PAI has faced practical limitations such as insufficient cell-specific targeting due to low delivery efficiency and difficulties in developing clinically translatable agents. Identifying these limitations is essential to the continuing expansion of the field, and substantial advances in developing contrast-enhancing agents, complemented by high-performance image acquisition systems, have synergistically dealt with the challenges of conventional PAI. This review covers the past four years of research on pushing the physical and practical challenges of PAI in terms of SNR/contrast, spatial resolution, targeted delivery, and clinical application. Promising strategies for dealing with each challenge are reviewed in detail, and future research directions for next generation contrast-enhanced PAI are discussed.

Dual-Responsive Nanocomposites for Synergistic Antibacterial Therapies Facilitating Bacteria-Infected Wound Healing

The rising dangers of bacterial infections have created an urgent need for the development of a new generation of antibacterial technologies and therapeutics. Antibacterial photodynamic therapy (PDT), considered as a noninvasive treatment with no drug resistance, has become a new promising photochemistry-involved treatment strategy. Titanium oxide (TiO₂ ) is proved to be a very efficient PDT agent among the photosensitive materials, while the property of a large bandgap of TiO₂ makes it only be excited by ultraviolet light, which is harmful to organisms. In this work, a novel ligand-to-metal charge transfer (LMCT) mediated TiO₂ PDT strategy is proposed via the harmless near-infrared light irradiation. By choosing a mussel-inspired material, polydopamine (PDA) is involved in forming mesoporous TiO₂ @PDA nanoparticles (mTiO₂ @PDA NPs). The catechol groups of PDA can attach the TiO₂ tightly even in colloidal environments, and can also form the LMCT bridge, exciting TiO₂ to exert PDT function via 808 nm irradiation. Combining the sonodynamic therapy (SDT) of TiO₂ and the photothermal therapy properties of PDA, this simple structure mTiO₂ @PDA enables synergistic antibacterial applications with multiple functions under the dual excitation of NIR and ultrasound. This reliable all-in-one NPs can achieve great antibacterial effect and a rapid repair of infected wounds.

Acoustic-Based Theranostic Probes Activated by Tumor Microenvironment for Accurate Tumor Diagnosis and Assisted Tumor Therapy

Acoustic-based imaging techniques, including ultrasonography and photoacoustic imaging, are powerful noninvasive approaches for tumor imaging owing to sound transmission facilitation, deep tissue penetration, and high spatiotemporal resolution. Usually, imaging modes were classified into "always-on" mode and "activatable" mode. Conventional "always-on" acoustic-based probes often have difficulty distinguishing lesion regions of interest from surrounding healthy tissues due to poor target-to-background signal ratios. As compared, activatable probes have attracted attention with improved sensitivity, which can boost or amplify imaging signals only in response to specific biomolecular recognition or interactions. The tumor microenvironment (TME) exhibits abnormal physiological conditions that can be used to identify tumor sections from normal tissues. Various types of organic dyes and biomaterials can react with TME, leading to obvious changes in their optical properties. The TME also affects the self-assembly or aggregation state of nanoparticles, which can be used to design activatable imaging probes. Moreover, acoustic-based imaging probes and therapeutic agents can be coencapsulated into one nanocarrier to develop nanotheranostic probes, achieving tumor imaging and cooperative therapy. Satisfactorily, ultrasound waves not only accelerate the release of encapsulated therapeutic agents but also activate therapeutic agents to exert or enhance their therapeutic performance. Meanwhile, various photoacoustic probes can convert photon energy into heat under irradiation, achieving photoacoustic imaging and cooperative photothermal therapy. In this review, we focus on the recently developed TME-triggered ultrasound and photoacoustic theranostic probes for precise tumor imaging and targeted tumor therapy.

Recent Progress Toward Imaging Application of Multifunction Sonosensitizers in Sonodynamic Therapy

Sonodynamic therapy (SDT) is a rapidly developing non-surgical therapy that initiates sensitizers’ catalytic reaction using ultrasound, showing great potential for cancer treatment due to its high safety and non-invasive nature. In addition, recent research has found that using different diagnostic and therapeutic methods in tandem can lead to better anticancer outcomes. Therefore, as essential components of SDT, sonosensitizers have been extensively explored to optimize their functions and integrate multiple medical fields. The review is based on five years of articles evaluating the combined use of SDT and imaging in treating cancer. By developing multifunctional sonosensitive particles that combine imaging and sonodynamic therapy, we have integrated diagnosis into the treatment of precision medicine applications, improving SDT cell uptake and antitumor efficacy utilizing different tumour models. This paper describes the imaging principle and the results of cellular and animal imaging of the multifunctional sonosensitizers. Efforts are made in this paper to provide data and design references for future SDT combined imaging research and clinical application development and to provide offer suggestions.

Looking deep inside tissue with photoacoustic molecular probes: a review

Significance

Deep tissue noninvasive high-resolution imaging with light is challenging due to the high degree of light absorption and scattering in biological tissue. Photoacoustic imaging (PAI) can overcome some of the challenges of pure optical or ultrasound imaging to provide high-resolution deep tissue imaging. However, label-free PAI signals from light absorbing chromophores within the tissue are nonspecific. The use of exogeneous contrast agents (probes) not only enhances the imaging contrast (and imaging depth) but also increases the specificity of PAI by binding only to targeted molecules and often providing signals distinct from the background.

Aim

We aim to review the current development and future progression of photoacoustic molecular probes/contrast agents.

Approach

First, PAI and the need for using contrast agents are briefly introduced. Then, the recent development of contrast agents in terms of materials used to construct them is discussed. Then, various probes are discussed based on targeting mechanisms, in vivo molecular imaging applications, multimodal uses, and use in theranostic applications.

Results

Material combinations are being used to develop highly specific contrast agents. In addition to passive accumulation, probes utilizing activation mechanisms show promise for greater controllability. Several probes also enable concurrent multimodal use with fluorescence, ultrasound, Raman, magnetic resonance imaging, and computed tomography. Finally, targeted probes are also shown to aid localized and molecularly specific photo-induced therapy.

Conclusions

The development of contrast agents provides a promising prospect for increased contrast, higher imaging depth, and molecularly specific information. Of note are agents that allow for controlled activation, explore other optical windows, and enable multimodal use to overcome some of the shortcomings of label-free PAI.

Minimally invasive nanomedicine: nanotechnology in photo-/ultrasound-/radiation-/magnetism-mediated therapy and imaging

Traditional treatments such as chemotherapy and surgery usually cause severe side effects and excruciating pain. The emergence of nanomedicines and minimally invasive therapies (MITs) has brought hope to patients with malignant diseases. Especially, minimally invasive nanomedicines (MINs), which combine the advantages of nanomedicines and MITs, can effectively target pathological cells/tissues/organs to improve the bioavailability of drugs, minimize side effects and achieve painless treatment with a small incision or no incision, thereby acquiring good therapeutic effects. In this review, we provide a comprehensive review of the research status and challenges of MINs, which generally refers to the medical applications of nanotechnology in photo-/ultrasound-/radiation-/magnetism-mediated therapy and imaging. Additionally, we also discuss their combined application in various fields including cancers, cardiovascular diseases, tissue engineering, neuro-functional diseases, and infectious diseases. The prospects, and potential bench-to-bedside translation of MINs are also presented in this review. We expect that this review can inspire the broad interest for a wide range of readers working in the fields of interdisciplinary subjects including (but not limited to) chemistry, nanomedicine, bioengineering, nanotechnology, materials science, pharmacology, and biomedicine.

Oxygen-deficient titanium dioxide-loaded black phosphorus nanosheets for synergistic photothermal and sonodynamic cancer therapy

Malignant tumors, particularly those located in deep tissues, have always been a grievous threat to human health. Sonodynamic therapy (SDT) has recently attracted great attention due to deep tissue penetration. However, the lack of effective sonosensitizers and the poor therapeutic efficacy severely limit their wider use. Herein, dual-functionalized black phosphorus nanosheets (BP@PEI-PEG, i.e., PPBP) integrating black oxygen-deficient titanium dioxide particles (B-TiO₂) were successfully constructed (PPBP-B-TiO₂) for synergistic photothermal (PTT)/sonodynamic therapy. In these nanocomposites, black titanium dioxide can enhance the separation of electrons (e^-) and holes (h⁺) due to the oxygen-deficient structure and significantly improves the production of reactive oxygen species (ROS) for SDT, while the BP nanosheets endow the nanocomposites with a higher photothermal conversion capability for photothermal therapy (η = 44.1%) which can prolong the blood circulation and improve the O₂ supply. In vivo experiments prove that PPBP-B-TiO₂ nanocomposites exhibited outstanding tumor inhibition efficacy and excellent biocompatibility. This work provides a prospective platform for combined photothermal/sonodynamic cancer therapy.

Listening to drug delivery and responses via photoacoustic imaging

Administrating pharmaceutic agents efficiently to achieve the therapeutic effect is the aim of all drug delivery techniques. Recent drug delivery systems aim to deliver high doses of drugs to disease sites accurately while maximizing therapeutic effects and minimizing potential side effects. Key approaches apply image guidance techniques for the quantification of drug biodistribution and pharmacokinetic parameters during drug delivery. This review highlights recent research on image-guided drug delivery systems based on photoacoustic imaging, which has been attracting attention for its non-invasiveness, non-ionizing radiation, and real-time imaging functions. Photoacoustic imaging based on the photothermal conversion efficiency of agents can be easily combined with various phototherapeutics, making them highly suitable for drug delivery therapy platforms. Here, we summarize and compare the characteristics of various types of photoacoustic imaging systems, focus on contrast-enhanced photoacoustic imaging and controlled release of therapeutics in drug delivery systems for synergistic therapies.

Nanoengineered Neutrophils as a Cellular Sonosensitizer for Visual Sonodynamic Therapy of Malignant Tumors

The rapid evolution of cell-based theranostics has attracted extensive attention due to their unique advantages in biomedical applications. However, the inherent functions of cells alone cannot meet the needs of malignant tumor treatment. Thus endowing original cells with new characteristics to generate multifunctional living cells may hold a tremendous promise. Here, the nanoengineering method is used to combine customized liposomes with neutrophils, generating oxygen-carrying sonosensitizer cells with acoustic functions, which are called Acouscyte/O₂ , for the visual diagnosis and treatment of cancer. Specifically, oxygen-carried perfluorocarbon and temoporfin are encapsulated into cRGD peptide modified multilayer liposomes (C-ML/HPT/O₂ ), which are then loaded into live neutrophils to obtain Acouscyte/O₂ . Acouscyte/O₂ can not only carry a large amount of oxygen but also exhibits the ability of long circulation, inflammation-triggered recruitment, and decomposition. Importantly, Acouscyte/O₂ can be selectively accumulated in tumors, effectively enhancing tumor oxygen levels, and triggering anticancer sonodynamics in response to ultrasound stimulation, leading to complete obliteration of tumors and efficient extension of the survival time of tumor-bearing mice with minimal systemic adverse effects. Meanwhile, the tumors can be monitored in real time by temoporfin-mediated fluorescence imaging and perfluorocarbon (PFC)-microbubble-enhanced ultrasound imaging. Therefore, the nanoengineered neutrophils, i.e., Acouscyte/O₂ , are a new type of multifunctional cellular drug, which provides a new platform for the diagnosis and sonodynamic therapy of solid malignant tumors.

Synthesis of manganese-oxide and palladium nanoparticles co-decorated polypyrrole/graphene oxide (MnO2@Pd@PPy/GO) nanocomposites for anti-cancer treatment

Design and fabrication of novel multifunctional nanomaterials as novel “theranostic nanoagents”with high efficiency and low side effects is important for cancer treatment. Herein, we synthesized manganese-oxide and palladium nanoparticle-co-decorated polypyrrole/graphene oxide (MnO₂@Pd@PPy/GO) nanocomposites, which could be used as a novel “theranostic nanoagent” for cancer treatment. Various spectroscopic and microscopic characterizations of the synthesized MnO₂@Pd@PPy/GO nanocomposites suggest that the nanocomposites are assembled sequentially by graphene oxide, polypyrrole, palladium nanoparticles and manganese-oxide nanoplates. Further research revealed that the nanocomposites had excellent photothermal conversion performance (reached near 50 °C after 10 min of irradiation), pH responsive enzymatic-like catalytic activity and enhanced magnetic resonance imaging (MRI) performance (r₁ = 7.74 mM⁻¹ s⁻¹ at pH 5.0 and glutathione (GSH)). Cell experiments also testified that combined cancer treatment (the viability of cancer cells is 30%) with photothermal therapy (PTT, the viability of cancer cells is 91% only with irradiation) and chemodynamic therapy (CDT, the viability of cancer cells is 74.7% only with nanocomposites) guided by MRI was achieved when the as-prepared nanocomposites were employed as theranostic nanoagents. This work could provide some new ideas for the controllable synthesis and application of multicomponent nanomaterials.

Manganese-oxide and palladium nanoparticle-co-decorated polypyrrole/graphene oxide (MnO₂@Pd@PPy/GO) nanoenzyme composites were synthesized, and could be as a novel “theranostic nanoagent” for cancer treatment due to excellent performance.

Combined Photothermotherapy and Chemotherapy of Oral Squamous Cell Carcinoma Guided by Multifunctional Nanomaterials Enhanced Photoacoustic Tomography

Background

Squamous cell carcinoma of the head and neck is the sixth most common cancer worldwide, with 40% occurring in the oral cavity. Although the level of early diagnosis and treatment of OSCC has improved significantly, the five-year survival rate of advanced patients remains unsatisfactory. However, the main challenges before us are how to get an early and accurate diagnosis and how to formulate effective treatment. Nanoparticle-based chemo-photothermal therapy has proven to be a promising non-invasive approach to treating oral squamous cell carcinoma treatment.

Methods

In this study, we tried to design and synthesize multifunctional hyaluronic acid (HA) modified gold nanorods/mesoporous silica-based nanoparticles loaded with doxorubicin hydrochloride (DOX) for photoacoustic imaging (PAI) guided cooperative chemo-photothermal therapy.

Results

The resultant nanocomposite shows favorable biocompatibility, relatively low cytotoxicity, ideal drug loading capability and strong PAI signals. In addition, they showed an excellent photothermal conversion efficiency of 49.02% for photothermal therapy (PTT). Moreover, in vivo and in vitro experiments have shown that synergistic chemo-photothermal therapy has better therapeutic effects than chemotherapy alone or PTT (P < 0.05). After being injected into the CAL-27 tumor-bearing mice, the DOX-AuNRs@mSiO₂-HA nanoparticles could accumulate rapidly at the tumor sites and achieve complete ablation of tumors when combined with near-infrared laser irradiation, without obvious side effects on normal tissues.

Conclusion

Our research provides a solid demonstration of the potential of DOX-AuNRs@mSiO₂-HA as a multifunctional platform in PAI-guided photothermal chemotherapy for oral squamous cell carcinoma.

NIR-activated self-sensitized polymeric micelles for enhanced cancer chemo-photothermal therapy

NIR-activated therapies based on light-responsive drug delivery systems are emerging as a remote-controlled method for cancer precise therapy. In this work, fluorescent dye indocyanine green (ICG)-conjugated and bioactive compound gambogic acid (GA)-loaded polymeric micelles (GA@PEG-TK-ICG PMs) were smoothly fabricated via the self-assembly of the reactive oxygen species (ROS)-responsive thioketal (TK)-linked amphiphilic polymer poly(ethyleneglycol)-thioketal-(indocyanine green) (PEG-TK-ICG). The resultant micelles demonstrated increased resistance to photobleaching, enhanced photothermal conversion efficiency, NIR-controlled drug release behavior, preferable biocompatibility, and excellent tumor accumulation performance. Moreover, upon an 808 nm laser irradiation, the micellar photoactive chromophore ICG converted the absorbed optical energy to both hyperthermia for photothermal therapy (PTT) and ROS as the feedback trigger to the micelles for the tumor-specific release of GA, which could serve as not only a chemotherapeutic drug to directly kill tumor cells but also a heat shock protein 90 (HSP90) inhibitor to realize the photothermal sensitization. As a result, an extremely high tumor inhibition rate (97.9%) of mouse 4 T1 breast cancer models was achieved with negligible side effects after the chemo-photothermal synergistic therapy. This NIR-activated nanosystem with photothermal self-sensitization function may provide a feasible option for the effective treatment of aggressive breast cancers.

Optimization of Nanoparticles for Smart Drug Delivery: A Review

Nanoparticle delivery systems have good application prospects in the treatment of various diseases, especially in cancer treatment. The effect of drug delivery is regulated by the properties of nanoparticles. There have been many studies focusing on optimizing the structure of nanoparticles in recent years, and a series of achievements have been made. This review summarizes the optimization strategies of nanoparticles from three aspects-improving biocompatibility, increasing the targeting efficiency of nanoparticles, and improving the drug loading rate of nanoparticles-aiming to provide some theoretical reference for the subsequent drug delivery of nanoparticles.

Near infrared photothermal conversion materials: mechanism, preparation, and photothermal cancer therapy applications

Photothermal therapy (PTT) has been widely applied in cancer therapy as a result of its non-invasive, localized treatment and good therapeutic effect. In general, the final therapeutic effect of PTT mainly depends on the photothermal materials, which can be further considered to be determined by the photothermal conversion efficiency, biocompatibility, and photothermal stability of photothermal materials. In this review, photothermal materials including inorganic materials, organic materials, and organic-inorganic composite materials in recent years have been summarized in terms of the mechanism, preparation, and cancer therapy applications. In the end, the perspectives and obstacles in their further development are overviewed.

Type I Photosensitizers Revitalizing Photodynamic Oncotherapy

Photodynamic therapy (PDT) has shown great potential for tumor treatment with merits of non-invasiveness, high selectivity, and minimal side effects. However, conventional type II PDT relying on ¹ O₂ presents poor therapeutic efficacy for hypoxic tumors due to the oxygen-dependent manner. Alternatively, emerging researches have demonstrated that type I PDT exhibits superiority over type II PDT in tumor treatment owing to its diminished oxygen-dependence. In this review, state-of-the-art studies concerning recent progress in type I photosensitizers are scrutinized, emphasizing the strategies to construct highly effective type I photosensitizers. As the foundation, basic principles of type I PDT are presented, and up-to-date type I photosensitizers are summarized and classified based on their attributes. Then, a literature review of representative type I photosensitizers (including nanomaterials and small molecules) is presented with impetus to delineate their novel designs, action mechanisms, as well as anticancer PDT applications. Finally, the remaining challenges and development directions of type I photosensitizers are outlined, highlighting key scientific issues toward clinical translations.

Recent advances in porous nanostructures for cancer theranostics

Porous nanomaterials with high surface area, tunable porosity, and large mesopores have recently received particular attention in cancer therapy and imaging. Introduction of additional pores to nanostructures not only endows the tunability of optoelectronic and optical features optimal for tumor treatment, but also modulates the loading capacity and controlled release of therapeutic agents. In recognition, increasing efforts have been made to fabricate various porous nanomaterials and explore their potentials in oncology applications. Thus, a systematic and comprehensive summary is necessary to overview the recent progress, especially in last ten years, on the development of various mesoporous nanomaterials for cancer treatment as theranostic agents. While outlining their individual synthetic mechanisms after a brief introduction of the structures and properties of porous nanomaterials, the current review highlighted the representative applications of three main categories of porous nanostructures (organic, inorganic, and organic-inorganic nanomaterials). In each category, the synthesis, representative examples, and interactions with tumors were further detailed. The review was concluded with deliberations on the key challenges and future outlooks of porous nanostructures in cancer theranostics.

Nanostructured TiO2 cavitation agents for dual-modal sonophotocatalysis with pulsed ultrasound

Current sonochemical methods rely on spatially uncontrolled cavitation for radical species generation to promote chemical reactions. To improve radical generation, sonosensitizers have been demonstrated to be activated by cavitation-based light emission (sonoluminescence). Unfortunately, this process remains relatively inefficient compared to direct photocatalysis, due to the physical separation between cavitation event and sonosensitizing agent. In this study, we have synthesized nanostructured titanium dioxide particles to couple the source for cavitation within a photocatalytic site to create a sonophotocatalyst. In doing so, we demonstrate that site-controlled cavitation from the nanoparticles using pulsed ultrasound at reduced acoustic powers resulted in the sonochemical degradation methylene blue at rates nearly three orders of magnitude faster than other titanium dioxide-based nanoparticles by conventional methods. Sonochemical degradation was directly proportional to the measured cavitation produced by these sonophotocatalysts. Our work suggests that simple nanostructuring of current sonosensitizers to enable on-site cavitation greatly enhances sonochemical reaction rates.

Inorganic chemoreactive nanosonosensitzers with unique physiochemical properties and structural features for versatile sonodynamic nanotherapies

The fast development of nanomedicine and nanobiotechnology has enabled the emerging of versatile therapeutic modalities with high therapeutic efficiency and biosafety, among which nanosonosensitizer-involved sonodynamic therapy (SDT) employs ultrasound (US) as the exogenous activation source for inducing the production of reactive oxygen species (ROS) and disease therapy. The chemoreactive nanosonosensitizers are the critical components participating in the SDT process, which generally determine the SDT efficiency and therapeutic outcome. Compared to the traditional and mostly explored organic sonosensitizers, the recently developed inorganic chemoreactive nanosonosensitizers feature the distinct high stability, multifunctionality and significantly different SDT mechanism. This review dominantly discusses and highlights two types of inorganic nanosensitizers in sonodynamic treatments of various diseases and their underlying therapeutic mechanism, including US-activated generation of electrons (e^-) and holes (h⁺) for facilitating the following ROS production and delivery of organic molecular sonosensitizers. Especially, this review proposes four strategies aiming for augmenting the SDT efficiency on antitumor and antibacterial applications based on inorganic sonosensitizers, including defect engineering, novel metal coupling, increasing electric conductivity and alleviating tumor hypoxia. The encountered challenges and critical issues facing these inorganic nanosonosensitzers are also highlighted and discussed for advancing their clinical translations.

Design and application of inorganic nanoparticles for sonodynamic cancer therapy

This review focus on the recent developments in inorganic nanomaterials for tumor SDT.

Tailored Mesoporous Inorganic Biomaterials: Assembly, Functionalization, and Drug Delivery Engineering

Infectious or immune diseases have caused serious threat to human health due to their complexity and specificity, and emerging drug delivery systems (DDSs) have evolved into the most promising therapeutic strategy for drug-targeted therapy. Various mesoporous biomaterials are exploited and applied as efficient nanocarriers to loading drugs by virtue of their large surface area, high porosity, and prominent biocompatibility. Nanosized mesoporous nanocarriers show great potential in biomedical research, and it has become the research hotspot in the interdisciplinary field. Herein, recent progress and assembly mechanisms on mesoporous inorganic biomaterials (e.g., silica, carbon, metal oxide) are summarized systematically, and typical functionalization methods (i.e., hybridization, polymerization, and doping) for nanocarriers are also discussed in depth. Particularly, structure-activity relationship and the effect of physicochemical parameters of mesoporous biomaterials, including morphologies (e.g., hollow, core-shell), pore textures (e.g., pore size, pore volume), and surface features (e.g., roughness and hydrophilic/hydrophobic) in DDS application are overviewed and elucidated in detail. As one of the important development directions, advanced stimuli-responsive DDSs (e.g., pH, temperature, redox, ultrasound, light, magnetic field) are highlighted. Finally, the prospect of mesoporous biomaterials in disease therapeutics is stated, and it will open a new spring for the development of mesoporous nanocarriers.

One-step synthesis of well-dispersed polypyrrole copolymers under gamma-ray irradiation

Herein, we report for the first time the synthesis of polypyrrole copolymers with good solvent-dispersibility under gamma-ray irradiation at room temperature in air.

Curcumin-gold-polyethylene glycol nanoparticles as a nanosensitizer for photothermal and sonodynamic therapies: In vitro and animal model studies

Photothermal and ultrasound therapies are novel non-invasive strategies for tumor treatment which are equipped with a photosensitizer and sonosensitizer subsequent activation by laser irradiation and ultrasound exposure. In this study, curcumin-gold-polyethylene glycol nanoparticles (Cur-Au NPs-PEG) were synthesized, and the dual role in photothermal (PTT) and sonodynamic (SDT) therapies of melanoma cancer was evaluated. The toxicity effect of Cur-Au NPs-PEG against a mouse malignant melanoma cell line C540 (B16/F10) was firstly inspected in vitro. Cur-Au NPs-PEG provided a hyperthermal microenvironment and generated reactive oxygen species upon PTT and STD, respectively, with representing synergism effects. Studies in vivo in a tumor-bearing animal also demonstrate the superiority of PTT and SDT in destroying melanoma tumor.

Recent Advances in Nanomaterial-Assisted Combinational Sonodynamic Cancer Therapy

Ultrasound (US)-triggered sonodynamic therapy (SDT), as a promising noninvasive therapeutic modality, has received ever-increasing attention in recent years. Its specialized chemical agents, named sonosensitizers, are activated by low-intensity US to produce lethal reactive oxygen species (ROS) for oncotherapy. Compared with phototherapeutic strategies, SDT provides many noteworthy opportunities and benefits, such as deeper penetration depth, absence of phototoxicity, and fewer side effects. Nevertheless, previous studies have also demonstrated its intrinsic limitations. Thanks to the facile engineering nature of nanotechnology, numerous novel nanoplatforms are being applied in this emerging field to tackle these intrinsic barriers and achieve continuous innovations. In particular, the combination of SDT with other treatment strategies has demonstrated a superior efficacy in improving anticancer activity relative to that of monotherapies alone. Therefore, it is necessary to summarize the nanomaterial-assisted combinational sonodynamic cancer therapy applications. Herein, the design principles in achieving synergistic therapeutic effects based on nanomaterial engineering methods are highlighted. The ultimate goals are to stimulate the design of better-quality combined sonodynamic treatment schemes and provide innovative ideas for the perspectives of SDT in promoting its future transformation to clinical application.

Sonodynamic therapy-derived multimodal synergistic cancer therapy

Sonodynamic therapy (SDT) represents a promising modality that provides the possibility of non-invasively eliminating solid tumors in a site-directed manner. In light of the complexity and heterogeneity of tumors, more and more studies are attempting to combine SDT with other therapeutic methods so as to achieve better tumor treatment effect, which sheds new light on the potential of SDT-based synergistic therapeutics. Herein, the representative studies of SDT-instructed multimodal synergistic cancer therapy are comprehensively presented, such as sono-chemotherapy, sono-radiotherapy, sono-immunotherapy, and sono-chemodynamic therapy, etc., and their incorporate mechanisms are discussed in detail. The current challenges and future prospects to promote the advanced development of SDT-based nanomedicines in this burgeoning research field are highlighted. It is believed that such an emerging synergistic therapeutic modality based on SDT will play a more significant role in the field of tumor precision treatment medicine.

Stealth Polymer-Coated Graphene Oxide Decorated Mesoporous Titania Nanoplatforms for In Vivo Chemo-Photodynamic Cancer Therapy

PURPOSE

The goal of this study was to develop chemotherapeutic drug-loaded photoactivable stealth polymer-coated silica based- mesoporous titania nanoplatforms for enhanced antitumor activity.

METHODS

Both in vitro and in vivo models of solvothermal treated photoactivable nanoplatforms were evaluated for efficient chemo-photothermal activity. A versatile nanocomposite that combined silica based- mesoporous titania nanocarriers (S-MTN) with the promising photoactivable agent, graphene oxide (G) modified with a stealth polymer (P) was fabricated to deliver chemotherapeutic agent, imatinib (I), (referred as S-MTN@IG-P) for near-infrared (NIR)-triggered drug delivery and enhanced chemo-photothermal therapy.

RESULTS

The fabricated S-MTN@IG-P nanoplatform showed higher drug loading (~20%) and increased drug release (~60%) in response to light in acidic condition (pH 5.0). As prepared nanoplatform significantly converted NIR light into thermal energy (43.2°C) to produce reactive oxygen species (ROS). The pronounced cytotoxic effect was seen in both colon cancer cells (HCT-116 and HT-29) that was mediated through the chemotherapeutic effect of imatinib and the photothermal and ROS generation effects of graphene oxide. In vivo study also showed that S-MTN@IG-P could significantly accumulate into the tumor area and suppress the tumor growth under NIR irradiation without any biocompatibility issues.

CONCLUSION

Cumulatively, the above results showed promising effects of S-MTN@IG-P for effective chemo-phototherapy of colon cancer.

Ultrasound-Activated Cascade Effect for Synergistic Orthotopic Pancreatic Cancer Therapy

In some malignant tumor, especially for pancreatic tumor, poor solid-tumor penetration of nanotherapeutics impedes their treatment efficacy. Herein, we develop a polymer-peptide conjugate with the deep tissue penetration ability, which undergoes a cascade process under ultrasound (US), including (1) the singlet oxygen ¹O₂ is generated by P18, (2) the thioketal bond is cleaved by the ¹O₂, (3) the departure of PEG chains leads to the in situ self-assembly, and (4) the resultant self-assembled PK nanoparticles show considerable cellular internalization. Owing to the synergistic effect of US on increasing the membrane permeability, the endocytosis and lysosome escape of PK nanoparticles are further enhanced effectively, resulting in the improved therapeutic efficacy. Thanks to the high tissue-penetrating depth and spatial precision of US, PTPK presents enhanced tumor inhibition in an orthotopic pancreatic tumor model. Therefore, the US-activated cascade effect offers a novel perspective for precision medicine and disease theranostics.

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PPCs in single molecule state present remarkable solid-tumor penetrability

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US induced in situ self-assembly of PPCs is verified

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Assembled nanoparticles and US synergistically contribute to the cellular internalization

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US-activated cascade effect leads to effective inhibition of pancreatic tumor growth

Ultrafine Titanium Monoxide (TiO1+x) Nanorods for Enhanced Sonodynamic Therapy

Ultrasound (US)-triggered sonodynamic therapy (SDT) that enables noninvasive treatment of large internal tumors has attracted widespread interest. For improvement in the therapeutic responses to SDT, more effective and stable sonosensitizers are still required. Herein, ultrafine titanium monoxide nanorods (TiO_1+x NRs) with greatly improved sono-sensitization and Fenton-like catalytic activity were fabricated and used for enhanced SDT. TiO_1+x NRs with an ultrafine rodlike structure were successfully prepared and then modified with polyethylene glycol (PEG). Compared to the conventional sonosensitizer, TiO₂ nanoparticles, the PEG-TiO_1+x NRs resulted in much more efficient US-induced generation of reactive oxygen species (ROS) because of the oxygen-deficient structure of TiO_1+x NR, which predominantly serves as the charge trap to limit the recombination of US-triggered electron-hole pairs. Interestingly, PEG-TiO_1+x NRs also exhibit horseradish-peroxidase-like nanozyme activity and can produce hydroxyl radicals (^•OH) from endogenous H₂O₂ in the tumor to enable chemodynamic therapy (CDT). Because of their efficient passive retention in tumors post intravenous injection, PEG-TiO_1+x NRs can be used as a sonosensitizer and CDT agent for highly effective tumor ablation under US treatment. In addition, no significant long-term toxicity of PEG-TiO_1+x NRs was found for the treated mice. This work highlights a new type of titanium-based nanostructure with great performance for tumor SDT.

Facile synthesis of polypyrrole-rhodamine B nanoparticles for self-monitored photothermal therapy of cancer cells

Photothermal therapy following microscopic temperature detection can avoid overheating effects or insufficient heating, and thus improve therapeutic efficacy. In this study, biocompatible dual-functional nanoparticles (NPs) are constructed from polypyrrole (PPy) and rhodamine B (RB) by a one-step modified polymerization method. The polypyrrole serves as a photothemal agent, and rhodamine B acts as a temperature-sensing probe. The polypyrrole-rhodamine B (PPy-RB) NPs possess a high photothermal effect on irradiation by 808 nm laser, and a competent temperature sensitivity for the real-time temperature monitoring based on the emission intensity response of rhodamine B. After acting on HepG2 cells, the PPy-RB NPs can effectively induce cancer cell death, and the microscopic temperature is monitored by fluorescence feedback from rhodamine B during PTT by laser confocal microscopy. Hence, the proposed approach can supply a facile and promising way for the fabrication of effective theranostic nanoplatforms assisted by self-monitoring of cancer therapeutic processes.

Insights into Theranostic Properties of Titanium Dioxide for Nanomedicine

Titanium dioxide (TiO2) nanostructures exhibit a broad range of theranostic properties that make them attractive for biomedical applications. TiO2 nanostructures promise to improve current theranostic strategies by leveraging the enhanced quantum confinement, thermal conversion, specific surface area, and surface activity. This review highlights certain important aspects of fabrication strategies, which are employed to generate multifunctional TiO2 nanostructures, while outlining post-fabrication techniques with an emphasis on their suitability for nanomedicine. The biodistribution, toxicity, biocompatibility, cellular adhesion, and endocytosis of these nanostructures, when exposed to biological microenvironments, are examined in regard to their geometry, size, and surface chemistry. The final section focuses on recent biomedical applications of TiO2 nanostructures, specifically evaluating therapeutic delivery, photodynamic and sonodynamic therapy, bioimaging, biosensing, tissue regeneration, as well as chronic wound healing.