In vivo Multi-scale Photoacoustic Imaging Guided Photothermal Therapy of Cervical Cancer based on Customized Laser System and Targeted Nanoparticles

Therapeutic and Contrast Agents for Photoacoustic Imaging-Guided Photothermal Therapy: A Narrative Review

Photoacoustic imaging is a hybrid modality that combines high-contrast and spectroscopy-based optical imaging specificity with the high spatial resolution of ultrasonography. This review highlights the development and progress of photoacoustic imaging technology over the past decade. This imaging technology has evolved to be more user-friendly, cost-effective, and portable, demonstrating its potential for diverse clinical applications. A potential clinical application lies in the use of photoacoustic imaging as a guiding tool for photothermal therapy. This review was conducted by initially filtering through three databases, namely, Google Scholar, PubMed, and Scopus, resulting in 460 articles published between 2019 and May 2023. Of these, 54 articles were deemed suitable for review after identification. The selected articles were research papers focusing on the development of therapeutic agents that enhance contrast in photoacoustic imaging. All reviewed articles tested these agents both in vitro and in vivo. This review focuses on wavelength absorption and radiation sources for photothermal therapy. The developed agents predominantly used NIR-I wavelengths, whereas the NIR-II region has been less explored, indicating significant potential for future research. This review provides comprehensive insights into the advancement of compounds serving as therapeutic agents and contrast agents in photoacoustic imaging-guided photothermal therapy.

Noninvasive Photothermal Therapy of Nasopharyngeal Cancer Guided by High Efficiency Optical-Absorption Nanomaterial Enhanced by NIR-II Photoacoustic Imaging

Background

Photothermal therapy (PTT) guided by photoacoustic imaging (PAI) using nanoplatforms has emerged as a promising strategy for cancer treatment due to its efficiency and accuracy. This study aimed to develop and synthesize novel second near-infrared region (NIR-II) absorption-conjugated polymer acceptor acrylate-substituted thiadiazoloquinoxaline-diketopyrrolopyrrole polymers (PATQ-DPP) designed specifically as photothermal and imaging contrast agents for nasopharyngeal carcinoma (NPC).

Methods

The PATQ-DPP nanoparticles were synthesized and characterized for their optical properties, including low optical band gaps. Their potential as PTT agents and imaging contrast agents for NPC was evaluated both in vitro and in vivo. The accumulation of nanoparticles at tumor sites was assessed post-injection, and the efficacy of PTT under near-infrared laser irradiation was investigated in a mouse model of NPC.

Results

Experimental results indicated that the PATQ-DPP nanoparticles exhibited significant photoacoustic contrast enhancement and favorable PTT performance. Safety and non-toxicity evaluations confirmed the biocompatibility of these nanoparticles. In vivo studies showed that PATQ-DPP nanoparticles effectively accumulated at NPC tumor sites and demonstrated excellent tumor growth inhibition upon exposure to near-infrared laser irradiation. Notably, complete elimination of nasopharyngeal tumors was observed within 18 days following PTT.

Discussion

The findings suggest that PATQ-DPP nanoparticles are a promising theranostic agent for NIR-II PAI and PTT of tumors. This innovative approach utilizing PATQ-DPP nanoparticles provides a powerful tool for the early diagnosis and precise treatment of NPC, offering a new avenue in the management of this challenging malignancy.

Optical imaging for early detection of cervical cancer: state of the art and perspectives

Significance

Cervical cancer is one of the major causes of death in females worldwide. HPV infection is the key cause of uncontrolled cell growth leading to cervical cancer. About 90% of cervical cancer is preventable because of the slow progression of the disease, giving a window of about 10 years for the precancerous lesion to be recognized and treated.

Aim

The present challenges for cervical cancer diagnosis are interobserver variation in clinicians' interpretation of visual inspection with acetic acid/visual inspection with Lugol's iodine, cost of cytology-based screening, and lack of skilled clinicians. The optical modalities can assist in qualitatively and quantitatively analyzing the tissue to differentiate between cancerous and surrounding normal tissues.

Approach

This work is on the recent advances in optical techniques for cervical cancer diagnosis, which promise to overcome the above-listed challenges faced by present screening techniques.

Results

The optical modalities provide substantial measurable information in addition to the conventional colposcopy and Pap smear test to clinically aid the diagnosis.

Conclusions

Recent optical modalities on fluorescence, multispectral imaging, polarization-sensitive imaging, microendoscopy, Raman spectroscopy, especially with the portable design and assisted by artificial intelligence, have a significant scope in the diagnosis of premalignant cervical cancer in future.

EGFR-targeted semiconducting polymer nanoparticles for photoacoustic imaging

Semiconducting polymer nanoparticles (SPN), formulated from organic semiconducting polymers and lipids, show promise as exogenous contrast agents for photoacoustic imaging (PAI). To fully realise the potential of this class of nanoparticles for imaging and therapeutic applications, a broad range of active targeting strategies, where ligands specific to receptors on the target cells are displayed on the SPN surface, are urgently needed. In addition, effective strategies for quantifying the level of surface modification are also needed to support development of ligand-targeted SPN. In this paper, we have developed methods to prepare SPN bearing peptides targeted to Epidermal Growth Factor Receptors (EGFR), which are overexpressed at the surface of a wide variety of cancer cell types. In addition to fully characterising these targeted nanoparticles by standard methods (UV-visible, photoacoustic absorption, dynamic light scattering, zeta potential and SEM), we have developed a powerful new NMR method to determine the degree of conjugation and the number of targeting peptides attached to the SPN. Preliminary in vitro experiments with the colorectal cancer cell line LIM1215 indicated that the EGFR-targeting peptide conjugated SPN were either ineffective in delivering the SPN to the cells, or that the targeting peptide itself destabilised the formulation. This in reinforces the need for effective characterisation techniques to measure the surface accessibility of targeting ligands attached to nanoparticles.

Ultrasound nanotheranostics: Toward precision medicine

Ultrasound (US) is a mechanical wave that can penetrate biological tissues and trigger complex bioeffects. The mechanisms of US in different diagnosis and treatment are different, and the functional application of commercial US is also expanding. In particular, recent developments in nanotechnology have led to a wider use of US in precision medicine. In this review, we focus on US in combination with versatile micro and nanoparticles (NPs)/nanovesicles for tumor theranostics. We first introduce US-assisted drug delivery as a stimulus-responsive approach that spatiotemporally regulates the deposit of nanomedicines in target tissues. Multiple functionalized NPs and their US-regulated drug-release curves are analyzed in detail. Moreover, as a typical representative of US therapy, sonodynamic antitumor strategy is attracting researchers' attention. The collaborative efficiency and mechanisms of US and various nano-sensitizers such as nano-porphyrins and organic/inorganic nanosized sensitizers are outlined in this paper. A series of physicochemical processes during ultrasonic cavitation and NPs activation are also discussed. Finally, the new applications of US and diagnostic NPs in tumor-monitoring and image-guided combined therapy are summarized. Diagnostic NPs contain substances with imaging properties that enhance US contrast and photoacoustic imaging. The development of such high-resolution, low-background US-based imaging methods has contributed to modern precision medicine. It is expected that the integration of non-invasive US and nanotechnology will lead to significant breakthroughs in future clinical applications.

Combined Photodynamic and Photothermal Therapy and Immunotherapy for Cancer Treatment: A Review

Photoactivation therapy based on photodynamic therapy (PDT) and photothermal therapy (PTT) has been identified as a tumour ablation modality for numerous cancer indications, with photosensitisers and photothermal conversion agents playing important roles in the phototherapy process, especially in recent decades. In addition, the iteration of nanotechnology has strongly promoted the development of phototherapy in tumour treatment. PDT can increase the sensitivity of tumour cells to PTT by interfering with the tumour microenvironment, whereas the heat generated by PTT can increase blood flow, improve oxygen supply and enhance the PDT therapeutic effect. In addition, tumour cell debris generated by phototherapy can serve as tumour-associated antigens, evoking antitumor immune responses. In this review, the research progress of phototherapy, and its research effects in combination with immunotherapy on the treatment of tumours are mainly outlined, and issues that may need continued attention in the future are raised.

A highly efficient polydopamine encapsulated clinical ICG theranostic nanoplatform for enhanced photothermal therapy of cervical cancer

Photothermal therapy (PTT) is a safe and efficient anti-tumor treatment. A photothermal agent (PTA) with good biocompatibility and strong photothermal properties is of great importance for PTT. In this study, near-infrared (NIR) excitable clinical indocyanine green (ICG) was utilized as a PTA and further encapsulated by another PTA polydopamine (PDA) to form highly stable and efficient ICG@PDA nanoparticles (NPs). Then the ICG@PDA NPs were modified with methoxy polyethylene glycol amine (mPEG2000-NH2) to form biocompatible ICG@PDA@PEG NPs. ICG@PDA@PEG NPs showed good water solubility and a spherical shape with an average size of 140 nm. Furthermore, the photothermal properties of ICG@PDA@PEG NPs were studied and excellent photothermal performance with a photothermal conversion efficiency of 43.7% under 808 nm laser irradiation was achieved. Then, the PTT properties of ICG@PDA@PEG NPs were confirmed on HeLa cells with an efficiency of 86.1%. Meanwhile, the in vivo biocompatibility and toxicity of ICG@PDA@PEG NPs were evaluated. No apparent in vivo toxicity was observed in 24 hours and 7 days. Next, in vivo PTT analysis was conducted for cervical tumor-bearing nude mice under 808 nm laser excitation. It showed a good anti-tumor effect in vivo. Thus, ICG@PDA@PEG NPs exhibited great potential for safe and efficient photothermal therapy in anti-tumor therapy.

Multi-Modal Optical Imaging and Combined Phototherapy of Nasopharyngeal Carcinoma Based on a Nanoplatform

Nasopharyngeal carcinoma (NPC) is a common malignant tumor of the head and neck with a high incidence rate worldwide, especially in southern China. Phototheranostics in combination with nanoparticles is an integrated strategy for enabling simultaneous diagnosis, real-time monitoring, and administration of precision therapy for nasopharyngeal carcinoma (NPC). It has shown great potential in the field of cancer diagnosis and treatment owing to its unique noninvasive advantages. Many Chinese and international research teams have applied nano-targeted drugs to optical diagnosis and treatment technology to conduct multimodal imaging and collaborative treatment of NPC, which has become a hot research topic. In this review, we aimed to introduce the recent developments in phototheranostics of NPC based on a nanoplatform. This study aimed to elaborate on the applications of nanoplatform-based optical imaging strategies and treatment modalities, including fluorescence imaging, photoacoustic imaging, Raman spectroscopy imaging, photodynamic therapy, and photothermal therapy. This study is expected to provide a scientific basis for further research and development of NPC diagnosis and treatment.

Efficient Photoacoustic Imaging With Biomimetic Mesoporous Silica-Based Nanoparticles

Indocyanine green (ICG), a near-infrared (NIR) fluorescent dye approved by the Food and Drug Administration (FDA), has been extensively used as a photoacoustic (PA) probe for PA imaging. However, its practical application is limited by poor photostability in water, rapid body clearance, and non-specificity. Herein, we fabricated a novel biomimetic nanoprobe by coating ICG-loaded mesoporous silica nanoparticles with the cancer cell membrane (namely, CMI) for PA imaging. This probe exhibited good dispersion, large loading efficiency, good biocompatibility, and homologous targeting ability to Hela cells in vitro. Furthermore, the in vivo and ex vivo PA imaging on Hela tumor-bearing nude mice demonstrated that CMI could accumulate in tumor tissue and display a superior PA imaging efficacy compared with free ICG. All these results demonstrated that CMI might be a promising contrast agent for PA imaging of cervical carcinoma.

Indocyanine Green-Based Theranostic Nanoplatform for NIR Fluorescence Image-Guided Chemo/Photothermal Therapy of Cervical Cancer

Purpose

Indocyanine green (ICG) is a favorable fluorescence nanoprobe for its strong NIR-I fluorescence emission and good photothermal capabilities. However, the stability and tumor targeting ability of ICG is poor, which limits its further applications. To further improve the photothermal and therapeutic efficiency of ICG, bovine serum albumin (BSA) was utilized to encapsulate the ICG and the chemotherapeutic drug doxorubicin (DOX) was loaded to form the BSA@ICG-DOX theranostic nanoplatform.

Methods

In this study, ICG-loaded BSA nanoparticles (NPs) and the BSA@ICG-DOX NPs were fabricated using reprecipitation methods. Next, the tumour inhibition ability and biocompatibility of the NPs were evaluated. A subcutaneous xenografted nude mice model was established and imaging guided synergetic therapy was performed with the assistance of BSA@ICG-DOX NPs under 808 nm laser irradiation.

Results

The BSA@ICG NPs exhibited strong NIR-I fluorescence emission, excellent photothermal properties, biocompatibility, and tumor targeting ability. To further improve the therapeutic efficiency, the chemotherapeutic drug doxorubicin (DOX) was loaded into the BSA@ICG NPs to form the BSA@ICG-DOX theranostic nanoplatform. The BSA@ICG-DOX NPs were spherical with an average size of ~194.7 nm. The NPs had high encapsulation efficiency (DOX: 19.96% and ICG: 60.57%), and drug loading content (DOX: 0.95% and ICG: 3.03%). Next, excellent NIR-I fluorescence and low toxicity of the BSA@ICG-DOX NPs were verified. Targeted NIR-I fluorescence images were obtained after intravenous injection of the NPs into the subcutaneous cervical tumors of the mice.

Conclusion

To improve the anti-tumor efficiency of the ICG@BSA NPs, the chemotherapeutic drug DOX was loaded into the BSA@ICG NPs. The NIR excitation/emission and targeted BSA@ICG-DOX NPs enables high-performance diagnosis and chemo/photothermal therapy of subcutaneous cervical tumors, providing a promising approach for further biomedical applications.