Photoinduced Electron Transfer-Based Glutathione-Sensing Theranostic Nanoprodrug with Self-Tracking and Real-Time Drug Release Monitoring for Cancer Treatment

The rapid development of nanomedicine has considerably advanced precision therapy for cancer treatment. Superior to traditional chemotherapy, emerging theranostic nanoprodrugs can effectively realize inherent self-tracking, targeted drug delivery, stimuli-triggered drug release, and reduced systemic toxicity of chemotherapeutic drugs. However, theranostic nanoprodrugs with real-time drug release monitoring have remained rare so far. In this work, we developed a new glutathione-responsive theranostic nanoprodrug with a high drug-loading content of 59.4 wt % and an average nanoscale size of 46 nm, consisting of the anticancer drug paclitaxel and a fluorescent imaging probe with a high fluorescence quantum yield, which are linked by a disulfide-based glutathione-sensitive self-immolating linker. The strong fluorescence emission of the fluorophore enables efficacious self-tracking and sensitive fluorescence "ON-OFF" glutathione sensing. Upon encountering high-level glutathione in cancer cells, the disulfide bond is cleaved, and the resulting linker halves spontaneously collapse into cyclic small molecules at the same pace, leading to the simultaneous release of the therapeutic drug and the fluorescence-OFF imaging probe. Thereby, the drug release process is efficiently monitored by the fluorescence change in the nanoprodrug. The nanoprodrugs exerted high cytotoxicity toward various cancer cells, especially for A549 and HEK-293 cells, in which the nanoprodrugs generated better therapeutic effects than free paclitaxel. Our work demonstrated a new modality of smart theranostic nanoprodrugs for precise cancer therapy.

Self-Monitoring Theranostic Nanomaterials: Emerging Visual Agents for Real-Time Monitoring of Tumor Treatment Processes

Self-monitoring in tumor therapy is a concept that allows for real-time monitoring of the location and state of applied nanomaterials. This monitoring relies on dynamic signals, such as wave or magnetic signals, which vary in response to changes in the location and state of nanomaterials. Dynamic changes in nanomaterials can be monitored using dynamic signals, making it possible to determine and control the treatment process. Theranostic nanomaterials, which possess unique physical and chemical properties, have recently been explored as a viable option for self-monitoring. With the help of self-monitoring, theranostic nanomaterials can guide themselves to achieve region-selective treatment with higher controllability and safety. In this review, self-monitoring theranostic nanomaterials will be introduced in three parts according to their roles during therapy: tumor accumulation, tumor therapy, and metabolism. The limitations and future challenges of current self-monitoring theranostic nanomaterials will also be discussed.

Potential Production of Theranostic Boron Nitride Nanotubes (64Cu-BNNTs) Radiolabeled by Neutron Capture

In this work, the radioisotope 64Cu was obtained from copper (II) chloride dihydrate in a nuclear research reactor by neutron capture, (63Cu(n,γ)64Cu), and incorporated into boron nitride nanotubes (BNNTs) using a solvothermal process. The produced 64Cu-BNNTs were analyzed by TEM, MEV, FTIR, XDR, XPS and gamma spectrometry, with which it was possible to observe the formation of64Cu nanoparticles, with sizes of up to 16 nm, distributed through nanotubes. The synthesized of 64Cu nanostructures showed a pure photoemission peak of 511 keV, which is characteristic of gamma radiation. This type of emission is desirable for Photon Emission Tomography (PET scan) image acquisition, as well as its use in several cancer treatments. Thus, 64Cu-BNNTs present an excellent alternative as theranostic nanomaterials that can be used in diagnosis and therapy by different techniques used in nuclear medicine.

Multifunctional Silica-Based Nanoparticles with Controlled Release of Organotin Metallodrug for Targeted Theranosis of Breast Cancer

Three different multifunctional nanosystems based on the tethering onto mesoporous silica nanoparticles (MSN) of different fragments such as an organotin-based cytotoxic compound Ph3Sn{SCH2CH2CH2Si(OMe)3} (MSN-AP-Sn), a folate fragment (MSN-AP-FA-Sn), and an enzyme-responsive peptide able to release the metallodrug only inside cancer cells (MSN-AP-FA-PEP-S-Sn), have been synthesized and fully characterized by applying physico-chemical techniques. After that, an in vitro deep determination of the therapeutic potential of the achieved multifunctional nanovectors was carried out. The results showed a high cytotoxic potential of the MSN-AP-FA-PEP-S-Sn material against triple negative breast cancer cell line (MDA-MB-231). Moreover, a dose-dependent metallodrug-related inhibitory effect on the migration mechanism of MDA-MB-231 tumor cells was shown. Subsequently, the organotin-functionalized nanosystems have been further modified with the NIR imaging agent Alexa Fluor 647 to give three different theranostic silica-based nanoplatforms, namely, MSN-AP-Sn-AX (AX-1), MSN-AP-FA-Sn-AX (AX-2), and MSN-AP-FA-PEP-S-Sn-AX (AX-3). Their in vivo potential as theranostic markers was further evaluated in a xenograft mouse model of human breast adenocarcinoma. Owing to the combination of the receptor-mediated site targeting and the specific fine-tuned release mechanism of the organotin metallodrug, the nanotheranostic drug MSN-AP-FA-PEP-S-Sn-AX (AX-3) has shown targeted diagnostic ability in combination with enhanced therapeutic activity by promoting the inhibition of tumor growth with reduced hepatic and renal toxicity upon the repeated administration of the multifunctional nanodrug.

Redox-Activated Light-Up Nanomicelle for Precise Imaging-Guided Cancer Therapy and Real-Time Pharmacokinetic Monitoring

Simultaneous tumor imaging, therapy, and pharmacokinetic monitoring can offer a safe and effective strategy for cancer therapy. This work describes the design of a fluorescence light-up nanomicelle that can afford precise imaging-guided drug delivery and pharmacokinetic monitoring in a real-time fashion for cancer chemotherapy. The nanomicelle, which contains a boron dipyrromethene based fluorescent probe as the hydrophobic core and a redox-triggered detachable poly(ethylene glycol) (PEG) shell, can accumulate at the tumor site via enhanced permeation and retention effect. The PEG detachment induced by tumoral and intracellular glutathione can destabilize the nanomicelle, leading to fluorescence light up and simultaneous drug release. Importantly, the fluorescence intensities generated by the nanomicelles in different organs are well-correlated with released drug concentrations in both temporal and spatial manners, suggesting its precise role for imaging-guided drug delivery and pharmacokinetic monitoring in vivo. The tumor growth can be effectively inhibited by the docetaxel-loaded nanomicelle formulation, and the nanomicelles are monitored to be excreted via hepatobiliary routes. This nanomicelle for precise imaging-guided chemotherapy provides a safe and robust theranostic strategy for the evaluation of cancer nanomedicine.