Quantitative imaging of light-triggered doxorubicin release

Using reflectometry to minimize the dependence of fluorescence intensity on optical absorption and scattering

The total diffuse reflectance RT and the effective attenuation coefficient µeff of an optically diffuse medium map uniquely onto its absorption and reduced scattering coefficients. Using this premise, we developed a methodology where RT and the slope of the logarithmic spatially resolved reflectance, a quantity related to µeff, are the inputs of a look-up table to correct the dependence of fluorescent signals on the media's optical properties. This methodology does not require an estimation of the medium's optical property, avoiding elaborate simulations and their errors to offer accurate and fast corrections. The experimental demonstration of our method yielded a mean relative error in fluorophore concentrations of less than 4% over a wide range of optical property variations. We discuss how the method developed can be employed to improve image fidelity and fluorochrome quantification in fluorescence molecular imaging clinical applications.

One-dimensional scanning multiphoton imaging reveals prolonged calcium transient and sarcomere contraction in a zebrafish model of doxorubicin cardiotoxicity

Doxorubicin (DOX) is a potent chemotherapeutic agent known to induce cardiotoxicity. Here we applied one-dimensional scanning multiphoton imaging to investigate the derangement of cardiac dynamics induced by DOX on a zebrafish model. DOX changed the cell morphology and significantly prolonged calcium transient and sarcomere contraction, leading to an arrhythmia-like contractile disorder. The restoration phase of calcium transient dominated the overall prolongation, indicating that DOX perturbed primarily the protein functions responsible for recycling cytosolic calcium ions. This novel finding supplements the existing mechanism of DOX cardiotoxicity. We anticipate that this approach should help mechanistic studies of drug-induced cardiotoxicity or heart diseases.

Labeling of Erythrocytes by Porphyrin-Phospholipid

A method is developed for membrane labeling of erythrocytes with porphyrin-phospholipid (PoP). To generate a concentrated PoP solution for labeling human red blood cells (RBCs), various surfactants and solvents are screened to identify conditions that avoid hemolysis, while minimizing non-specific PoP co-precipitation with RBCs in the pellet during centrifugation washes. Cholate, Tween 80 and Tween 40 are identified as useful surfactants for this purpose. When labeled RBCs are mixed with unlabeled ones, substantial non-specific PoP exchange is observed. Egg-yolk lecithin is included in a washing buffer to remove loosely bound PoP and reduce PoP exchange with unlabeled erythrocytes, based on flow cytometry and photodynamic hemolysis assays. Murine RBCs that are labeled with ⁶⁴Cu-chelated PoP displayed altered biodistribution with longer blood circulation relative to directly administered ⁶⁴Cu-chelated PoP.

Optoacoustic properties of Doxorubicin - A pilot study

Doxorubicin (DOX) is a widely used chemotherapeutic anticancer drug. Its intrinsic fluorescence properties enable investigation of tumor response, drug distribution and metabolism. First phantom studies in vitro showed optoacoustic property of DOX. We therefore aimed to further investigate the optoacoustic properties of DOX in biological tissue in order to explore its potential as theranostic agent. We analysed doxorubicin hydrochloride (Dox·HCl) and liposomal encapsulated doxorubicin hydrochloride (Dox·Lipo), two common drugs for anti-cancer treatment in clinical medicine. Optoacoustic measurements revealed a strong signal of both doxorubicin substrates at 488 nm excitation wavelength. Post mortem analysis of intra-tumoral injections of DOX revealed a detectable optoacoustic signal even at three days after the injection. We thereby demonstrate the general feasibility of doxorubicin detection in biological tissue by means of optoacoustic tomography, which could be applied for high resolution imaging at mesoscopic depths dictated by effective penetration of visible light into the biological tissues.

Self-Propelled and Targeted Drug Delivery of Poly(aspartic acid)/Iron-Zinc Microrocket in the Stomach

For many medical treatments, particularly cancer, it is necessary to develop a biocompatible microscale device that can carry a sufficient amount of a drug and deliver it to target sites. While chemically powered micromotors have been applied in live animal therapy, many of them are difficult to biodegrade in vivo, which might cause toxicity and side effects. Here, we report on a microdevice that consists of a poly(aspartic acid) (PASP) microtube, a thin Fe intermediate layer, and a core of Zn. This device can be propelled using gastric acid as a fuel. After adsorption of doxorubicin onto a PASP surface, the microrocket can carry drugs, magnetically locate targets, permeate the gastric mucus gel layer, and increase drug retention in the stomach without inducing an obvious toxic reaction. All materials in the microrockets are biocompatible and biodegradable and can be readily decomposed by the gastric acid or by proteases in the digestive tract. Such microrockets, made with poly(amino acid)s, will extend the practical biomedical applications of micro- and nanomotors.

Metalloporphyrin Nanoparticles: Coordinating Diverse Theranostic Functions

Metalloporphyrins serve key roles in natural biological processes and also have demonstrated utility for biomedical applications. They can be encapsulated or grafted in conventional nanoparticles or can self-assemble themselves at the nanoscale. A wide range of metals can be stably chelated either before or after porphyrin nanoparticle formation, without the necessity of any additional chelator chemistry. The addition of metals can substantially alter a range of behaviors such as modulating phototherapeutic efficacy; conferring responsiveness to biological stimuli; or providing contrast for magnetic resonance, positron emission or surface enhanced Raman imaging. Chelated metals can also provide a convenient handle for bioconjugation with other molecules via axial coordination. This review provides an overview of some recent biomedical, nanoparticulate approaches involving gain-of-function metalloporphyrins and related molecules.

Review of structured light in diffuse optical imaging

Diffuse optical imaging probes deep living tissue enabling structural, functional, metabolic, and molecular imaging. Recently, due to the availability of spatial light modulators, wide-field quantitative diffuse optical techniques have been implemented, which benefit greatly from structured light methodologies. Such implementations facilitate the quantification and characterization of depth-resolved optical and physiological properties of thick and deep tissue at fast acquisition speeds. We summarize the current state of work and applications in the three main techniques leveraging structured light: spatial frequency-domain imaging, optical tomography, and single-pixel imaging. The theory, measurement, and analysis of spatial frequency-domain imaging are described. Then, advanced theories, processing, and imaging systems are summarized. Preclinical and clinical applications on physiological measurements for guidance and diagnosis are summarized. General theory and method development of tomographic approaches as well as applications including fluorescence molecular tomography are introduced. Lastly, recent developments of single-pixel imaging methodologies and applications are reviewed.

Multifunctional Nanosystem for Targeted and Controlled Delivery of Multiple Chemotherapeutic Agents for the Treatment of Drug-Resistant Breast Cancer

By targeting CD44 receptors, inhibiting multidrug resistance (MDR), controlling drug release, and synergistically inhibiting tumor growth, a multilayered nanosystem was developed to serve as a multifunctional platform for the treatment of drug-resistant breast cancers. The multilayer nanosystem is composed of a poly(lactic-co-glycolic acid) core, a liposome second layer, and a chitosan third layer. The chitosan-multilayered nanoparticles (Ch-MLNPs) can co-deliver three chemotherapeutic agents: doxorubicin (DOX), paclitaxel (PTX), and silybin. The three drugs are released from the multilayered NPs in a controlled and sequential manner upon internalization and localization in the cellular endosomes. The presence of a chitosan layer allows the nanosystem to target a well-characterized MDR breast cancer biomarker, the CD44s receptor. In vitro cytotoxicity study showed that the nanosystem loaded with triple drugs, DOX-PTX-silybin, resulted in better antitumor efficacy than the single-drug or dual-drug nano-formulations. Likely attributed to the MDR-inhibition effect of silybin, the co-delivered DOX and PTX exhibited a better synergistic effect on MDR breast cancer cells than on non-MDR breast cancer cells. The in vivo study also showed that the multilayered nanosystem promoted MDR inhibition and synergy between chemotherapeutic agents, leading to significant tumor reduction in a xenograft animal model. Ch-MLNPs reduced the tumor volume by fivefold compared to that of the control group without causing overt cytotoxicity.

A dual-channel endoscope for quantitative imaging, monitoring, and triggering of doxorubicin release from liposomes in living mice

Doxorubicin (Dox) is approved for use in liposomal form for the treatment of ovarian cancer. We previously developed a long-circulating Dox formulation in liposomes containing small amounts of porphyrin-phospholipid, which enables on-demand drug release with near-infrared irradiation. In this study, we present and evaluate a dual-modal, dual-channel light endoscope that allows quantitative reflectance and fluorescence imaging for monitoring of local Dox concentrations in target areas. The endoscope consists of two flexible imaging fibers; one to transmit diagnostic and therapeutic light to the target, and the other to detect fluorescent and reflected light. Thus, the endoscope serves for imaging, for light delivery to trigger drug release, and for monitoring drug concentration kinetics during drug release. We characterized the performance of this endoscope in tissue phantoms and in an in vivo model of ovarian cancer. This study demonstrates the feasibility of non-invasive, quantitative mapping of Dox distribution in vivo via endoscopic imaging.

Sphingomyelin Liposomes Containing Porphyrin-phospholipid for Irinotecan Chemophototherapy

Porphyrin-phospholipid (PoP) liposomes can entrap anti-cancer agents and release them in response to near infrared (NIR) light. Doxorubicin, when remotely loaded via an ammonium sulfate gradient at a high drug-to-lipid ratio, formed elongated crystals that altered liposome morphology and could not be loaded into liposomes with higher PoP content. On the other hand, irinotecan could also be remotely loaded but did not form large crystals and did not induce liposome elongation. The loading, stability, and NIR light-triggered release of irinotecan in PoP liposomes was altered by the types of lipids used and the presence of PEGylation. Sphingomyelin, which has been explored previously for liposomal irinotecan, was found to produce liposomes with relatively improved serum stability and rapid NIR light-triggered drug release. PoP liposomes composed from sphingomyelin, cholesterol and 2 molar percent PoP rapidly released irinotecan in vivo in response to NIR irradiation as monitored by intravital microscopy and also induced effective tumor eradication in mice bearing MIA Paca-2 subcutaneous tumor xenografts.

Mechanisms of Light-induced Liposome Permeabilization

Liposomes have been widely studied for drug delivery applications. The inclusion of photoactive molecules into liposomes opens the possibility of light‐controlled cargo release to enhance drug biodistribution or bioavailability at target sites. Membrane permeabilization induced by light can be an effective strategy for enhancing cargo delivery with spatial and temporal control, which holds potential for chemophototherapy approaches. Several diverse mechanisms have been reported including light‐induced oxidation, photocrosslinking, photoisomerization, photocleavage, and photothermal release. Here, we review selected recent reports of light‐triggered cargo release from liposomes.