Fluorescence color-changeable branched-form heptamethine cyanine dye as a redox-responsive multi-functional drug delivery system for enhanced cancer diagnosis and chemophototherapy

Controllable Drug-Release Ratio and Rate of Doxorubicin-Loaded Natural Composite Films Based on Polysaccharides: Evaluation of Transdermal Permeability Potential

In drug delivery systems, it is crucial to develop a drug carrier capable of regulating both the drug-release rate and the drug-release ratio. This study proposes a method for controlling the drug-release ratio/rate using doxorubicin-loaded natural composite films composed of polysaccharides (cellulose, chitin, chitosan, or cellulose nanocrystal) and mineral substances (MMT: montmorillonite). We succeeded in controlling the doxorubicin release ratio from 25 to 88% depending on the natural polysaccharide. Likewise, the reduction rate differed depending on the type of natural polysaccharide, whereas the reduction in release was achieved by mixing MMT. Cellulose had the largest reduction in the drug release ratio, approximately 30%, and cellulose nanocrystals showed little change. Furthermore, we conducted a skin permeation test on the natural polysaccharide film with the highest release rate to confirm its transdermal permeability potential. The polysaccharide doxorubicin-loaded film sustainably released doxorubicin for 2 days, which indicated the potential of a carrier for DDS applications.

Polymethine dyes for PDT: recent advances and perspectives to drive future applications

It has been proved that the effectiveness of photodynamic therapy (PDT) is closely related to the intrinsic features of the photosensitizer (PS). Over the recent years, several efforts have been devoted to the discovery of novel and more efficient photosensitizers showing higher efficacy and lower side effects. In this context, squaraine and cyanine dyes have been reported to potentially overcome the drawbacks related to the traditional PSs. In fact, squaraines and cyanines are characterized by sharp and intense absorption bands and narrow emission bands with high extinction coefficients typically in the red and near-infrared region, good photo and thermal stability and a strong fluorescent emission in organic solvents. In addition, biocompatibility and low toxicity make them suitable for biological applications. Despite these interesting intrinsic features, their chemical instability and self-aggregation properties in biological media still limit their use in PDT. To overcome these drawbacks, the self-assembly and incorporation into smart nanoparticle systems are forwarded promising approaches that can control their physicochemical properties, providing rational solutions for the limitation of free dye administration in the PDT application. The present review summarizes the latest advances in squaraine and cyanine dyes for PDT application, analyzing the different strategies, i.e.the self-assembly and the incorporation into nanoparticles, to further enhance their photochemical properties and therapeutic potential. The in vivo assessments are still limited, thus further delaying their effective application in PDT.

Construction of synergistic pH/H2O2-responsive prodrug for prolonging blood circulation and accelerating cellular internalization

We have developed a real-time and multifunctional doxifluridine-conjugate prodrug (LYX), which involved the preliminary methylfluorescein with 5-fluorouracil linker as protecting group, the targeting biotin unit, and a model therapeutic drug (doxifluridine). The shielding group (5'-DFUR) was found to be effective in prolonging circulation at physiological pH 7.4 and improving accumulation in the acidic microenvironment of the tumor. Based on this strategy, the stability and stimulus responsive properties of prodrug could enhance drug release efficiency and exhibit fewer side effects, thereby providing a unique opportunity for diagnosis and imaging additional analytes or enzymatic activities.

Intraperitoneal Injection of Cyanine-Based Nanomicelles for Enhanced Near-Infrared Fluorescence Imaging and Surgical Navigation in Abdominal Tumors

Fluorescent surgical navigation can effectively aid tumor resection. As one of the most popular near-infrared (NIR) fluorophores, cyanine dye has the outstanding optical ability and the potential to act as a fluorescence probe for tumors. Herein, we report a polyethylene glycol-modified amphiphilic cyanine dye (Cy7-NPC) with an NIR luminescence performance, which can self-assemble to form uniform nanomicelles (Cy7-NPC-S) and which can be applied for the optical imaging of abdominal tumors and for fluorescence imaging-guided precision tumor resection. When applied to biological imaging, Cy7-NPC-S showed high biological safety, strong tissue penetration depth for optical imaging, and high optical imaging resolution. Intraperitoneal administration of Cy7-NPC-S produced remarkable imaging efficacy in abdominal tumors. Compared with intravenous injection, abdominal tumors took up intraperitoneal Cy7-NPC-S faster and in greater quantities, thus enabling Cy7-NPC-S to facilitate accurate recognition and extirpation of abdominal tumors in fluorescence-guided surgery. We believe that metabolizable Cy7-NPC-S with NIR luminescence has promising applications and value in the fields of in vivo imaging and fluorescent surgical navigation.

Endogenous Enzyme-responsive Nanoplatforms for Anti-tumor Therapy

The emergency of responsive drug delivery systems has contributed to reduced cytotoxicity, improved permeability in tissues and extended circulation time of the active drug. In particular, enzyme-responsive nanoplatforms have attracted a lot of attention due to the specificity and efficiency of an enzyme-catalyzed reaction. In this review, enzyme-based mono responsive drug delivery systems designed in the past 5 years have been summarized. These drug delivery systems were introduced by different tumor-related enzymes such as matrix metalloproteinase, esterase, hyaluronidase, caspase and cathepsin. Moreover, the enzyme-sensitive nanoplatforms activated by dual-stimuli have been also described. Although great progress had been made in the past years, the translation into clinical practice is still difficult. Thus, three obstacles (enzyme heterogeneity, reaction environment, animal model) were also discussed. In short, enzyme-activated drug delivery systems offer great potential in treating cancers.