Band 10, Heft 12 - Special Issue: Nanophotonics and immunotherapy for cancer; Guest Editors: Feifan Zhou, Tayyaba Hasan, Celine Frochot, Wei R. Chen

Nanotechnology, photonics, and immunotherapy are far-reaching technologies with the potential to revolutionize the field of cancer diagnostics and therapeutics. While each technology has limitations in cancer treatment, they can be synergized to exert profound impact on the balance and modulation of immunoediting in tumor microenvironment (TME) and in the entire host immune system. We provide our perspectives on how nano-photo-immuno interactions can be used as an effective therapy, particularly when combined with other treatment modalities, such as checkpoint immune therapy, chemotherapy, and TME modulation, to provide a long-term, tumor-specific immunity against tumor metastasis and tumor recurrence.

Treatment of malignant tumors has always been a worldwide challenge. The complexity, diversity, and heterogeneity of tumors have prompted the treatment strategies to gradually shift from monotherapy to combination therapy that can synergize multiple treatment modalities. With unique physical and chemical properties, nanomaterials have been widely used in different cancer therapies, including chemotherapy, immunotherapy, and phototherapy. Especially, the variability and integrity of nanomaterials make them ideal media for synergistic collaboration strategies. Here, we provide our perspective on the synergistic strategy of nanoplatform-mediated phototherapies and related combination therapies, specifically photochemotherapy, photoradiotherapy, and photoimmunotherapy. Besides, we provide an analysis and outlook on the current challenges faced by synergistic nanophototherapy.

Cancer has gained much attention because of slow development of advanced diagnostics and therapeutic strategies. So far, conventional procedures like surgery, radiation therapy and chemotherapy are only available options for cancer treatment which have various limitations. To overcome the limitations of conventional procedures, nanodiagnostics, and therapeutics are emerging approaches for localized diagnosis and treatment of cancer nowadays. So far, various bio-mimicking and stimuli active cancer theranostic platforms have been established but they are limited only for animal studies and their clinical translational progress is slow. Among various cancer theranostics platforms, photoresponsive systems have shown promising outcomes for cancer theranostics applications due to their specific physicochemical properties, biocompatibility, multifunctionality etc. Moreover, these photothermal agents in combination with diagnostics probes and surface functional targeting moieties demonstrate their synergistic response for site selective imaging and ablating cancer cells/tumor. Photoactive principles are rife and with increasing access to light irradiation setups, more the discovery of photoactive products, more would be the success reaped in cancer battle. This review highlights recent developments in cancer nanotheranostics with a special focus on photoactive functional nanotheranostics. Moreover, the challenges involved in clinical translation of photoactive materials along with their application in vivid areas of cancer nanomedicine and elucidate the future implications on photoactive therapy have been addressed here.

Persistent luminescence (PerL) materials continue emitting light long after their excitation has stopped. Prepared in the form of nanoparticles they revealed their full potential as bio-nanoprobes for in vivo small animal imaging in the last 15 years. PerL materials enable to overcome the limitation of weak light penetration in living tissues. As such, they constitute remarkable light mediators to implement photodynamic therapy (PDT) in deep-seated tissues. This article reviews the recent achievements in PerL-mediated PDT in vitro as well as in small animal cancer models in vivo . PerL-mediated PDT is realized through the smart choice of a tandem of a PerL material and a photosensitizer (PS). The physical association of the PerL material and the PS as well as their targeting ability is debated. Implants or mesoporous nanoparticles emerge as particularly valuable cargos that further permit multimodality in imaging or therapy. The diversity of charge-trapping mechanisms in a few PerL materials enables a large versatility in the excitation protocols. Although the PerL agent can be pre-excited by UV light before its introduction into the animal, it also induces effective PDT after simple infrared or visible LED illumination across tissues as well as after a mild X-ray irradiation.

In recent years, the spin Hall effect of light (SHE), also called the photonic spin Hall effect has received extensive research attention, and a series of interesting results have been achieved. This phenomenon has potential applications in nanooptics, quantum information, and optoelectronic devices. In contrast to the pure photon SHE, the photonic spin Hall effect in the surface plasmonic platform exhibits unique properties due to the surface plasmon resonance effect of noble metal material and establishes the connection between photons and electrons. Therefore, the SHE of light in a surface plasmonic platform is expected to be applied to integrated optical devices to create a novel means of developing communication devices. In this paper, we review the progress on the SHE of light based on the plasmonic platform in recent years, and we discuss the future directions of research and prospects for its applications.

Cancer is the second leading cause of death worldwide after cardiovascular disease. Depending on the type and the location of the tumor, several cancer treatments are implemented. Among these, the three most conventional therapies are surgery, radiotherapy and chemotherapy. However, there are other therapeutic approaches such as photodynamic therapy (PDT). PDT relies on the combined action of light, a photoactivable molecule called photosensitizer (PS) and molecular oxygen. Most of the PSs used for clinical applications are not cancer-cell specific. One of the solutions to overcome this problem is the use of nanoparticles (NPs) to induce a passive targeting. It is also possible to graft a vector onto the NPs to specifically target membrane receptors overexpressed in the tumor cells or neovessels surrounding the tumor. In this review, we focus on the NPs loaded with PSs and coupled to peptides for targeted PDT. We described nanosystems that targeted Neuropilin-1 (NRP-1), α v β 3 integrins, nucleolin membrane receptor, epidermal growth factor (EGF) receptor, protein-glutamine-gamma-glutamyltransferase (TGM2), p32, transferrin, PD-1, and mitochondrial membrane. The use of a cell absorbing-peptide is also described.

Near-infrared photoimmunotherapy (NIR-PIT) is a new cancer treatment that uses an antibody-photo-absorber conjugate (APC) composed of a targeting monoclonal antibody conjugated with a photoactivatable phthalocyanine-derivative dye, IRDye700DX (IR700). APCs injected into the body can bind to cancer cells where they are activated by local exposure to NIR light typically delivered by a NIR laser. NIR light alters the APC chemical conformation inducing damage to cancer cell membranes, resulting in necrotic cell death within minutes of light exposure. NIR-PIT selectivity kills cancer cells by immunogenic cell death (ICD) with minimal damage to adjacent normal cells thus, leading to rapid recovery by the patient. Moreover, since NIR-PIT induces ICD only on cancer cells, NIR-PIT initiates and activates antitumor host immunity that could be further enhanced when combined with immune checkpoint inhibition. NIR-PIT induces dramatic changes in the tumor vascularity causing the super-enhanced permeability and retention (SUPR) effect that dramatically enhances nanodrug delivery to the tumor bed. Currently, a worldwide Phase 3 study of NIR-PIT for recurrent or inoperable head and neck cancer patients is underway. In September 2020, the first APC and accompanying laser system were conditionally approved for clinical use in Japan. In this review, we introduce NIR-PIT and the SUPR effect and summarize possible applications of NIR-PIT in a variety of cancers.

Phototherapy usually includes photodynamic therapy (PDT) and photothermal therapy (PTT) to induce cell death. PDT utilizes the sensitization of the photosensitizers to generate reactive oxygen species by the intersystem crossing while PTT undergoes nonradiative decay to generate heat. Cancer immunotherapy has evolved as a new therapeutic modality to eradicate tumor cells by activating antigen-presenting cells, and thus, inducing innate or adaptive immune responses. Phototherapy is able to stimulate the immune system, usually by inducing immunogenic cell death (ICD). Photoimmunotherapy (PIT) is an oncological treatment that combines the phototherapy of the tumor with immunotherapy treatment. Combining phototherapy with immunotherapy enhances the immunostimulating response and has synergistic effects for metastatic cancer treatment. PIT is able to enhance the antitumor immune response by ICD and prevent tumor metastases and recurrence. In this review article, we would like to summarize the recent advances in the development of phototherapy (such as PDT, PTT, and synergistic PDT/PTT) triggered immunotherapy for cancer treatment. In addition, immunotherapy triggered by phototherapy and other therapeutic modalities will be discussed. PIT may be a win-win strategy to fight against cancer.

Immunotherapy has provided a new avenue to treat metastatic cancers, which result in ∼90% of cancer related deaths. However, current immunotherapies, such as immune checkpoint therapy (ICT), have met with limited success, primarily due to tumor intrinsic and extrinsic factors that inhibit antitumor immune responses. To overcome the immune suppression of the tumor microenvironment (TME) and enhance the tumoricidal activity of ICT, phototherapy, particularly photothermal therapy (PTT), combined with nanomedicine has become a viable option. PTT disrupts target tumor homeostasis, releasing tumor associated antigens (TAAs), tumor specific antigens (TSAs), danger associated molecular patterns (DAMPs), and scarce nutrients required to “feed” activated antitumor immune cells. While nanoparticles localize and specify the phototherapeutic effect, they can also be loaded with immune stimulants, TME modulators, and/or chemotherapeutic agents to greatly enhance immune stimulation and tumor killing. Combining these three technologies, which we term nano-ablative immunotherapy (NAIT), with ICT can greatly enhance their therapeutic effects. In this review, we will discuss the successes and limitations of NAIT + ICT. Specifically, we will discuss how the TME limits tumoricidal activity and what should be considered to overcome these limitations.

Cancer is the second leading cause of death and there is an urgent need to improve cancer management. We have developed an innovative cancer therapy named Sy nergistic I m muno Pho tothermal N anotherap y (SYMPHONY) by combining gold nanostars (GNS)-mediated photothermal ablation with checkpoint inhibitor immunotherapy. Our previous studies have demonstrated that SYMPHONY photoimmunotherapy not only treats the primary tumor but also dramatically amplifies anticancer immune responses in synergy with checkpoint blockade immunotherapy to treat remote and unresectable cancer metastasis. The SYMPHONY treatment also induces a ‘cancer vaccine’ effect leading to immunologic memory and prevents cancer recurrence in murine animal models. This manuscript provides an overview of our research activities on the SYMPHONY therapy with plasmonic GNS for cancer treatment.

Accurate detection of ATP-binding cassette drug transporter ABCB1 expression is imperative for precise identification of drug-resistant tumors. Existing detection methods fail to provide the necessary molecular details regarding the functional state of the transporter. Photoimmunoconjugates are a unique class of antibody–dye conjugates for molecular diagnosis and therapeutic treatment. However, conjugating hydrophobic photosensitizers to hydrophilic antibodies is quite challenging. Here, we devise a photoimmunoconjugate that combines a clinically approved benzoporphyrin derivative (BPD) photosensitizer and the conformational-sensitive UIC2 monoclonal antibody to target functionally active human ABCB1 (i.e., ABCB1 in the inward-open conformation). We show that PEGylation of UIC2 enhances the BPD conjugation efficiency and reduces the amount of non-covalently conjugated BPD molecules by 17%. Size exclusion chromatography effectively separates the different molecular weight species found in the UIC2–BPD sample. The binding of UIC2–BPD to ABCB1 was demonstrated in lipidic nanodiscs and ABCB1-overexpressing triple negative breast cancer (TNBC) cells. UIC2–BPD was found to retain the conformation sensitivity of UIC2, as the addition of ABCB1 modulators increases the antibody reactivity in vitro . Thus, the inherent fluorescence capability of BPD can be used to label ABCB1-overexpressing TNBC cells using UIC2–BPD. Our findings provide insight into conjugation of hydrophobic photosensitizers to conformation-sensitive antibodies to target proteins expressed on the surface of cancer cells.

Targeted delivery of drugs to tumor cells, which circumvent resistance mechanisms and induce cell killing, is a lingering challenge that requires innovative solutions. Here, we provide two bioengineered strategies in which nanotechnology is blended with cancer medicine to preferentially target distinct mechanisms of drug resistance. In the first ‘case study’, we demonstrate the use of lipid–drug conjugates that target molecular signaling pathways, which result from taxane-induced drug tolerance via cell surface lipid raft accumulations. Through a small molecule drug screen, we identify a kinase inhibitor that optimally destroys drug tolerant cancer cells and conjugate it to a rationally-chosen lipid scaffold, which enhances anticancer efficacy in vitro and in vivo . In the second ‘case study’, we address resistance mechanisms that can occur through exocytosis of nanomedicines. Using adenocarcinoma HeLa and MCF-7 cells, we describe the use of gold nanorod and nanoporous vehicles integrated with an optical antenna for on-demand, photoactivation at ∼650 nm enabling release of payloads into cells including cytotoxic anthracyclines. Together, these provide two approaches, which exploit engineering strategies capable of circumventing distinct resistance barriers and induce killing by multimodal, including nanophotonic mechanisms.

Nanobody-targeted photodynamic therapy (NB-PDT) has been developed as a potent and tumor-selective treatment, using nanobodies (NBs) to deliver a photosensitizer (PS) specifically to cancer cells. Upon local light application, reactive oxygen species are formed and consequent cell death occurs. NB-PDT has preclinically shown evident success and we next aim to treat cats with oral squamous cell carcinoma (OSCC), which has very limited therapeutic options and is regarded as a natural model of human head and neck SCC. Immunohistochemistry of feline OSCC tissue confirmed that the epidermal growth factor receptor (EGFR) is a relevant target with expression in cancer cells and not in the surrounding stroma. Three feline OSCC cell lines were employed together with a well-characterized human cancer cell line (HeLa), all with similar EGFR expression, and a low EGFR-expressing human cell line (MCF7), mirroring the EGFR expression level in the surrounding mucosal stroma. NB A was identified as a NB binding human and feline EGFR with comparable high affinity. This NB was developed into NiBh, a NB-PS conjugate with high PS payload able to effectively kill feline OSCC and HeLa cell lines, after illumination. Importantly, the specificity of NB-PDT was confirmed in co-cultures where only the feline OSCC cells were killed while surrounding MCF7 cells were unaffected. Altogether, NiBh can be used for NB-PDT to treat feline OSCC and further advance NB-PDT towards the human clinic.

We report on the irradiation of gold rod–sphere assemblies with ultrashort laser pulses, producing structures that are very difficult to obtain by other methods. The optical response of these assemblies displays several peaks arising from the interaction of the plasmon modes of the individual particles, offering thus great flexibility to control the energy deposited on the individual particles. Judicious selection of the wavelength and fluence of the laser pulses allow fine control over the changes produced: the particles can be melted, welded and/or the organic links cleaved. In this way, it is possible to generate structures “à la carte” with a degree of control unmatched by other synthetic protocols. The method is exemplified with gold nanoparticles, but it can be easily implemented on particles composed of different metals, widening considerably the range of possibilities. The final structures are excellent candidates for surface-enhanced spectroscopies or plasmonic photothermal therapy as they have a very intense electric field located outside the structure, not in the gaps.

Porphysomes (PS) are liposome-like nanoparticles comprising pyropheophorbide-conjugated phospholipids that have demonstrated potential as multimodal theranostic agents for applications that include phototherapies, targeted drug delivery and in vivo fluorescence, photoacoustic, magnetic resonance or positron emission imaging. Previous therapeutic applications focused primarily on photothermal therapy (PTT) and suggested that PSs require target-triggered activation for use as photodynamic therapy (PDT) sensitizers. Here, athymic nude mice bearing subcutaneous A549 human lung tumors were randomized into treatment and control groups: PS-PDT at various doses, PS-only and no treatment negative controls, as well as positive controls using the clinical photosensitizer Photofrin. Animals were followed for 30 days post-treatment. PS-PDT at all doses demonstrated a significant tumor ablative effect, with the greatest effect seen with 10 mg/kg PS at a drug-light interval of 24 h. By comparison, negative controls (PS-only, Photofrin-only, and no treatment) showed uncontrolled tumor growth. PDT with Photofrin at 5 mg/kg and PS at 10 mg/kg demonstrated similar tumor growth suppression and complete tumor response rates (15 vs. 25%, p  = 0.52). Hence, porphysome nanoparticles are an effective PDT agent and have the additional advantages of multimodal diagnostic and therapeutic applications arising from their intrinsic structure. Porphysomes may also be the first single all-organic agent capable of concurrent PDT and PTT.

Near-infrared (NIR)-activable liposomes containing photosensitizer (PS)-lipid conjugates are emerging as tunable, high-payload, and tumor-selective platforms for photodynamic therapy (PDT)-based theranostics. To date, the impact that the membrane composition of a NIR-activable liposome (the chemical nature and subsequent conformation of PS-lipid conjugates) has on their in vitro and in vivo functionality has not been fully investigated. While their chemical nature is critical, the resultant physical conformation dictates their interactions with the immediate biological environments. Here, we evaluate NIR-activable liposomes containing lipid conjugates of the clinically-used PSs benzoporphyrin derivative (BPD; hydrophobic, membrane-inserting conformation) or IRDye 700DX (hydrophilic, membrane-protruding conformation) and demonstrate that membrane composition is critical for their function as tumor-selective PDT-based platforms. The PS-lipid conformations were primarily dictated by the varying solubilities of the two PSs and assisted by their lipid conjugation sites. Conformation was further validated by photophysical analysis and computational predictions of PS membrane partitioning (topological polar surface area [tPSA], calculated octanol/water partition [cLogP], and apparent biomembrane permeability coefficient [P app ]). Results show that the membrane-protruding lipo-IRDye700DX exhibits 5-fold more efficient photodynamic generation of reactive molecular species (RMS), 12-fold expedited phototriggered burst release of entrap-ped agents, and 15-fold brighter fluorescence intensity as compared to the membrane-inserting lipo-BPD-PC (phosphatidylcholine conjugate). Although the membrane-inserting lipo-BPD-PC exhibits less efficient photo-dynamic generation of RMS, it allows for more sustained phototriggered release, 10-fold greater FaDu cancer cell phototoxicity, and 7.16-fold higher tumor-selective delivery in orthotopic mouse FaDu head and neck tumors. These critical insights pave the path for the rational design of emerging NIR-activable liposomes, whereby functional consequences of membrane composition can be tailored toward a specific therapeutic purpose.

Rapid establishment of herd immunity with vaccination is effective to combat emerging infectious diseases. Although the incorporation of adjuvant and intradermal (ID) injection could augment early responses to the vaccine, the current chemical or biological adjuvants are inappropriate for this purpose with their side effects and high reactogenicity in the skin. Recently, a near-infrared (NIR) laser has been shown to augment the immune response to ID vaccination and could be alternatively used for mass vaccination programs. Here, we determined the effect of NIR laser as well as licensed chemical adjuvants on the immunogenicity 1, 2, and 4 weeks after ID influenza vaccination in mice. The NIR laser adjuvant augmented early antibody responses, while the widely used alum adjuvant induced significantly  delayed responses. In addition, the oil-in-water and alum adjuvants, but not the NIR laser, elicited escalated T H 2 responses with allergenic immunoglobulin E (IgE) responses. The effect of the NIR laser was significantly suppressed in the basic leucine zipper transcription factor ATF-like 3 (Batf3) knockout mice, suggesting a critical role of the cluster of differentiation 103 + (CD103) + dendritic cells. The current preliminary study suggests that NIR laser adjuvant is an alternative strategy to chemical and biological agents to timely combat emerging infectious diseases. Moreover, its immunomodulatory property could be used to enhance the efficacy of immunotherapy for allergy and cancer.

Photodynamic priming ( PDP ), a collateral effect of photodynamic therapy, can transiently alter the tumor microenvironment (TME) beyond the cytotoxic zone. Studies have demonstrated that PDP increases tumor permeability and modulates immune-stimulatory effects by inducing immunogenic cell death, via the release of damage-associated molecular patterns and tumor-associated antigens. Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest of cancers with a stubborn immunosuppressive TME and a dense stroma, representing a challenge for current molecular targeted therapies often involving macromolecules. We, therefore, tested the hypothesis that PDP’s TME modulation will enable targeted therapy and result in immune stimulation. Using triple-receptor-targeted photoimmuno-nanoconjugate (TR-PINs)-mediated PDP , targeting epidermal growth factor receptor, transferrin receptor, and human epidermal growth factor receptor 2 we show light dose-dependent TR-PINs mediated cytotoxicity in human PDAC cells (MIA PaCa-2), co-cultured with human pancreatic cancer-associated fibroblasts (PCAFs) in spheroids. Furthermore, TR-PINs induced the expression of heat shock proteins (Hsp60, Hsp70), Calreticulin, and high mobility group box 1 in a light dose and time-dependent manner. TR-PINs-mediated T cell activation was observed in co-cultures of immune cells with the MIA PaCa-2-PCAF spheroids. Both CD4 + T and CD8 + T cells showed light dose and time-dependant antitumor reactivity by upregulating degranulation marker CD107a and interferon-gamma post-PDP. Substantial tumor cell death in immune cell-spheroid co-cultures by day 3 shows the augmentation by antitumor T cell activation and their ability to recognize tumors for a light dose-dependent kill. These data confirm enhanced destruction of heterogeneous pancreatic spheroids mediated by PDP -induced phototoxicity, TME modulation and increased immunogenicity with targeted nanoconstructs.

The blood-brain barrier (BBB) has a significant contribution to the protection of the central nervous system (CNS). However, it also limits the brain drug delivery and thereby complicates the treatment of CNS diseases. The development of safe methods for an effective delivery of medications and nanocarriers to the brain can be a revolutionary step in the overcoming this limitation. Here, we report the unique properties of the lymphatic system to deliver tracers and liposomes to the brain meninges, brain tissues, and glioma in rats. Using a quantum-dot-based 1267 nm laser (for photosensitizer-free generation of singlet oxygen), we clearly demonstrate photostimulation of lymphatic delivery of liposomes to glioma as well as lymphatic clearance of liposomes from the brain. These pilot findings open promising perspectives for photomodulation of lymphatic delivery of drugs and nanocarriers to the brain pathology bypassing the BBB. The lymphatic “smart” delivery of liposomes with antitumor drugs in the new brain tumor branches might be a breakthrough strategy for the therapy of gliomas.

Treatment of pancreatic cancer is faced with great difficulties and challenges due to high lethality and metastasis. Synergism of targeted therapy and immunotherapy has been considered as ideal strategy to both eliminate primary tumors and control metastases. For the treatment of advanced pancreatic cancer, we demonstrated a local photothermal therapy (PTT) following administration of monoclonal antibody of programmed death ligand 1 (αPD-L1). Fe 2 P nanorods were employed as a Fenton agent and photothermal agent, which modified with DSPE-PEG 2000 -Mal for improved biocompatibility and Mal mediated-antigen presentation. Under a low dose laser irradiation at 980 nm, Fe 2 P-PEG-Mal nanorods (NRs) mediated PTT could induce immunogenic tumor cell death that can cause dendritic cells (DCs) infiltration and maturation. In a bilateral pancreatic tumor model, the local treatment of NRs-PTT on primary tumor could cause the increased infiltration of cytotoxic T lymphocytes (CTLs) and decreased residential of M2 macrophages in untreated distal tumors. Furthermore, subsequently intervened αPD-L1 could enhance cell death triggered by CTLs in distal tumors through reversing immunosuppression. An orthotopic pancreatic tumor model was used to further confirm the therapeutic outcome. Finally, the combination of NRs based PTT and αPD-L1 based immunotherapy was able to significantly eliminate orthotopic pancreatic tumors and reduce mesentery metastases. Thus, the strategy may provide a more effective treatment for pancreatic cancer.

While photodynamic therapy (PDT) can induce acute inflammation in the irradiated tumor site, a sustained systemic, adaptive immune response is desirable, as it may control the growth of nonirradiated distant disease. Previously, we developed porphyrin lipoprotein (PLP), a ∼20 nm nanoparticle photosensitizer, and observed that it not only efficiently eradicated irradiated primary VX2 buccal carcinomas in rabbits, but also induced regression of nonirradiated metastases in a draining lymph node. We hypothesized that PLP-mediated PDT can induce an abscopal effect and we sought to investigate the immune mechanism underlying such a response in a highly aggressive, dual subcutaneous AE17-OVA+ mesothelioma model in C57BL/6 mice. Four cycles of PLP-mediated PDT was sufficient to delay the growth of a distal, nonirradiated tumor four-fold relative to controls. Serum cytokine analysis revealed high interleukin-6 levels, showing a 30-fold increase relative to phosphate-buffered solution (PBS) treated mice. Flow cytometry revealed an increase in CD4+ T cells and effector memory CD8+ T cells in non-irradiated tumors. Notably, PDT in combination with PD-1 antibody therapy prolonged survival compared to monotherapy and PBS. PLP-mediated PDT shows promise in generating a systemic immune response that can complement other treatments, improving prognoses for patients with metastatic cancers.

We designed novel biocompatible nanocomposite composed of gold nanorods coated with rod-like mesoporous silica SBA-15-SH particles, (GNRs@SBA-15-SH) as a new synergistic therapeutic device to deliver heat and drug to cancer cells for tumor eradication. For this purpose, doxorubicin (DOX) was loaded into GNRs@SBA-15-SH nanocomposites and studied their photothermal therapy, chemotherapy and the combined effect on the ablation of A549 cells in vitro using human lung cancer cells, A549. The results demonstrate the high photothermal efficacy of gold nanorods loaded into the nanocomposite, the thermo-responsive properties of GNRs@SBA-15-SH, the high loading capacity of DOX into the GNRs@SBA-15-SH and its biocompatibility. Synergistic chemo-photothermal of the GNRs@SBA-15-SH/DOX nanocomposite in the eradication of cancer cells under laser irradiation (808 nm), demonstrates the high potential of therapeutic efficacy of this combined therapy over monotherapies.

Immunotherapy has made great progress in recent years while most cancer patients cannot benefit from it. Photochemotherapy combination strategy holds great promise for developing novel immunotherapy for the patients bearing immunosuppressive tumors such as colon cancer. In this research, a novel core/shell-structured polydopamine (PDA)-based nanoplatform is constructed to load two Food and Drug Administration (FDA)-approved cytotoxic drugs, i.e. immunostimulatory doxorubicin (Dox) and immunomodulatory curcumin (Cur) to achieve immunostimulatory photochemotherapy of primary colon tumors upon 808 nm near infrared (NIR) irradiation (1 W/cm 2 for 5 min) and subsequent prevention of rechallenged distant colon tumors. The experimental data have shown that PDA-mediated photothermal therapy (PTT) synergized two therapeutic drugs in inducing colon cancer cell death and very efficiently inhibited the primary tumor growth (by ∼92%) at very low doses of therapeutics (0.25, 5, and 30 mg/kg of Dox, Cur, and PDA, respectively). More significantly, the combined photochemotherapy promoted strong adaptive antitumor immune responses and successfully prevented tumorigenesis in the setting of tumor rechallenge model. Our research has thus demonstrated the promising efficacy of this photochemotherapeutic nanoformulation for colon cancer treatment and provided a way to improve immunostimulatory effects of conventional chemotherapeutic drugs.

Black phosphorus (BP) is attracting more and more interest for the biomedical application. The absorption in a wide spectral range and high photothermal conversion efficiency make BP suitable for photothermal therapy. However, BP alone is hard to realize the targeted therapy, which limits the precision and efficiency of the therapy. Magnetic microbubbles (MBs) are favored drug carriers because they can resist the sheer force of blood flow in a magnetic field, which improves the efficiency of MBs adhesion to the vascular wall for targeted ultrasound diagnosis and therapy. This study first optimized the magnetic MBs configurations through controlling the connecting polyethylene glycol (PEG) chain length. The magnetic MBs with PEG2000 have been chosen for targeted BP nanosheets delivery due to the better stability and magnetic responsiveness. The magnetic black phosphorus microbubbles (MB BPM ) can realize the targeted tumor theranostics in vitro and in vivo . They could be applied for the targeted ultrasound imaging with an enhanced echogenicity by three times when accumulated at the target site where the magnetic field is applied. As the NIR laser irradiation was applied on the accumulated MB BPM , they dynamited and the temperature increased rapidly. It improved the cell membrane permeability, thus accelerating and enhancing a precision photothermal killing effect to the breast cancer cells, compared to BP alone.

Although photothermal therapy (PTT) has demonstrated its clinical value and adaptability, it still requires imaging guidance to motivate the development of precise and effective treatment. For PTT, high-resolution visualization of tumor microvasculature and accurate location of nanoparticles distribution are crucial for the therapeutic outcome. Here, a wavelength-switchable photoacoustic microscopy (PAM) was developed to noninvasively investigate the tumor microvasculature and the accumulation of nanoparticles for accurately guiding PTT and evaluating the therapeutic effect. In a tumor model, PAM was used to continuously monitor the tumor microenvironment in vivo , and the proportion of microvessels in tumor site was found increased by 10%, and the diameters of the draining veins were doubled on day 7. In addition, quantitative parameters such as tumor volume and vascular density can also be demonstrated by the PAM. Meanwhile, the concentration of Den-RGD/Cy7 at the tumor site reached its maximum at 8 h by PA mapping after intravenous injection, which was used to determine the optimal irradiation timing. After treatment, photoacoustic monitoring showed that PTT can precisely kill the tumors and minimize damage to surrounding normal tissues, which was consistent with the pathological slides. The experimental results proved that PAM can provide an auxiliary means for precision PTT.

The liver has a unique vascular structure and regional immunosuppressive characteristics closely linked to the occurrence and development of diseases. There are no long-term, large-field, and high-quality imaging methods to simultaneously obtain the structure of blood vessels and movement activities of immune cells in abdominal organs in vivo. This research developed a drawer-type abdominal window with an acrylic/resin coverslip named DAWarc and applied it to the intravital fluorescence/photoacoustic imaging of the liver for over 10 days. The liver lobe was inserted into the drawer holder of the DAWarc to physically fix the liver, which decreased the imaging artifacts. The acrylic/resin material used as the coverslip has a high compatibility for fluorescence/photoacoustic imaging. Through intravital fluorescence/photoacoustic imaging, information on the structure of hepatic lobules, spatial distribution of nanopomegranate labeled Kupffer cells (KCs), the movement behavior of invariant natural killer T cells, and morphology of KCs were obtained. We also used a self-organizing map neural network to detect tumor metastases in the photoacoustic images automatically. Conclusively, the DAWarc model provided a powerful tool for intravital fluorescence/photoacoustic imaging of the liver; it helped us to better understand the structure of hepatic lobules and the distribution and function of immune cells during the occurrence and development of liver diseases.