<i>T</i>₁ and <i>T</i>₂ Dual-Mode MRI Contrast Agent for Enhancing Accuracy by Engineered Nanomaterials

One of the holy grails in biomedical imaging technology is to achieve accurate imaging of biological targets. The development of sophisticated instrumentation and the use of contrast agents have improved the accuracy of biomedical imaging. However, the issue of false imaging remains a problem. Here, we developed a dual-mode artifact filtering nanoparticle imaging agent (AFIA) that comprises a combination of paramagnetic and superparamagnetic nanomaterials. This AFIA has the ability to perform “AND logic gate” algorithm to eliminate false errors (artifacts) from the raw images to enhance accuracy of the MRI. We confirm the artifact filtering capability of AFIA in MRI phantoms and further demonstrate that artifact-free imaging of stem cell migration is possible <i>in vivo</i>

Design Considerations of Iron-Based Nanoclusters for Noninvasive Tracking of Mesenchymal Stem Cell Homing

Stem-cell-based therapies have attracted considerable interest in regenerative medicine and oncological research. However, a major limitation of systemic delivery of stem cells is the low homing efficiency to the target site. Here, we report a serendipitous finding that various iron-based magnetic nanoparticles (MNPs) actively augment chemokine receptor CXCR4 expression of bone-marrow-derived mesenchymal stem cells (MSCs). On the basis of this observation, we designed an iron-based nanocluster that can effectively label MSCs, improve cell homing efficiency, and track the fate of the cells <i>in vivo</i>. Using this nanocluster, the labeled MSCs were accurately monitored by magnetic resonance imaging and improved the homing to both traumatic brain injury and glioblastoma models as compared to unlabeled MSCs. Our findings provide a simple and safe method for imaging and targeted delivery of stem cells and extend the potential applications of iron-based MNPs in regenerative medicine and oncology

Molecular Recognition Enables Nanosubstrate-Mediated Delivery of Gene-Encapsulated Nanoparticles with High Efficiency

Substrate-mediated gene delivery is a promising method due to its unique ability to preconcentrate exogenous genes onto designated substrates. However, many challenges remain to enable continuous and multiround delivery of the gene using the same substrates without depositing payloads and immobilizing cells in each round of delivery. Herein we introduce a gene delivery system, nanosubstrate-mediated delivery (NSMD) platform, based on two functional components with nanoscale features, including (1) DNA⊂SNPs, supramolecular nanoparticle (SNP) vectors for gene encapsulation, and (2) Ad-SiNWS, adamantane (Ad)-grafted silicon nanowire substrates. The multivalent molecular recognition between the Ad motifs on Ad-SiNWS and the β-cyclodextrin (CD) motifs on DNA⊂SNPs leads to dynamic assembly and local enrichment of DNA⊂SNPs from the surrounding medium onto Ad-SiNWS. Subsequently, once cells settled on the substrate, DNA⊂SNPs enriched on Ad-SiNWS were introduced through the cell membranes by intimate contact with individual nanowires on Ad-SiNWS, resulting in a highly efficient delivery of exogenous genes. Most importantly, sequential delivery of multiple batches of exogenous genes on the same batch cells settled on Ad-SiNWS was realized by sequential additions of the corresponding DNA⊂SNPs with equivalent efficiency. Moreover, using the NSMD platform <i>in vivo</i>, cells recruited on subcutaneously transplanted Ad-SiNWS were also efficiently transfected with exogenous genes loaded into SNPs, validating the <i>in vivo</i> feasibility of this system. We believe that this nanosubstrate-mediated delivery platform will provide a superior system for <i>in vitro</i> and <i>in vivo</i> gene delivery and can be further used for the encapsulation and delivery of other biomolecules

Cross-Linked Fluorescent Supramolecular Nanoparticles as Finite Tattoo Pigments with Controllable Intradermal Retention Times

Tattooing has been utilized by the medical community for precisely demarcating anatomic landmarks. This practice is especially important for identifying biopsy sites of nonmelanoma skin cancer (NMSC) due to the long interval (<i>i.e.</i>, up to 3 months) between the initial diagnostic biopsy and surgical treatment. Commercially available tattoo pigments possess several issues, which include causing poor cosmesis, being mistaken for a melanocytic lesion, requiring additional removal procedures when no longer desired, and potentially inducing inflammatory responses. The ideal tattoo pigment for labeling of skin biopsy sites for NMSC requires (i) invisibility under ambient light, (ii) fluorescence under a selective light source, (iii) a finite intradermal retention time (<i>ca.</i> 3 months), and (iv) biocompatibility. Herein, we introduce cross-linked fluorescent supramolecular nanoparticles (c-FSNPs) as a “finite tattoo” pigment, with optimized photophysical properties and intradermal retention time to achieve successful <i>in vivo</i> finite tattooing. Fluorescent supramolecular nanoparticles encapsulate a fluorescent conjugated polymer, poly­[5-methoxy-2-(3-sulfopropoxy)-1,4-phenylenevinylene] (MPS-PPV), into a core <i>via</i> a supramolecular synthetic approach. FSNPs which possess fluorescent properties superior to those of the free MPS-PPV are obtained through a combinatorial screening process. Covalent cross-linking of FSNPs results in micrometer-sized c-FSNPs, which exhibit a size-dependent intradermal retention. The 1456 nm sized c-FSNPs display an ideal intradermal retention time (<i>ca.</i> 3 months) for NMSC lesion labeling, as observed in an <i>in vivo</i> tattoo study. In addition, the c-FSNPs induce undetectable inflammatory responses after tattooing. We believe that the c-FSNPs can serve as a “finite tattoo” pigment to label potential malignant NMSC lesions

Pretargeted Positron Emission Tomography Imaging That Employs Supramolecular Nanoparticles with <i>in Vivo</i> Bioorthogonal Chemistry

A pretargeted oncologic positron emission tomography (PET) imaging that leverages the power of supramolecular nanoparticles with <i>in vivo</i> bioorthogonal chemistry was demonstrated for the clinically relevant problem of tumor imaging. The advantages of this approach are that (i) the pharmacokinetics (PKs) of tumor-targeting and imaging agents can be independently altered <i>via</i> chemical alteration to achieve the desired <i>in vivo</i> performance and (ii) the interplay between the two PKs and other controllable variables confers a second layer of control toward improved PET imaging. In brief, we utilized supramolecular chemistry to synthesize tumor-targeting nanoparticles containing transcyclooctene (TCO, a bioorthogonal reactive motif), called TCO⊂SNPs. After the intravenous injection and subsequent concentration of the TCO⊂SNPs in the tumors of living mice, a small molecule containing both the complementary bioorthogonal motif (tetrazine, Tz) and a positron-emitting radioisotope (⁶⁴Cu) was injected to react selectively and irreversibly to TCO. High-contrast PET imaging of the tumor mass was accomplished after the rapid clearance of the unreacted ⁶⁴Cu-Tz probe. Our nanoparticle approach encompasses a wider gamut of tumor types due to the use of EPR effects, which is a universal phenomenon for most solid tumors

Cross-Linked Fluorescent Supramolecular Nanoparticles for Intradermal Controlled Release of Antifungal DrugA Therapeutic Approach for Onychomycosis

The existing approaches to onychomycosis demonstrate limited success since the commonly used oral administration and topical cream only achieve temporary effective drug concentration at the fungal infection sites. An ideal therapeutic approach for onychomycosis should have (i) the ability to introduce antifungal drugs directly to the infected sites; (ii) finite intradermal sustainable release to maintain effective drug levels over prolonged time; (iii) a reporter system for monitoring maintenance of drug level; and (iv) minimum level of inflammatory responses at or around the fungal infection sites. To meet these expectations, we introduced ketoconazole-encapsulated cross-linked fluorescent supramolecular nanoparticles (KTZ⊂c-FSMNPs) as an intradermal controlled release solution for treating onychomycosis. A two-step synthetic approach was adopted to prepare a variety of KTZ⊂c-FSMNPs. Initial characterization revealed that 4800 nm KTZ⊂c-FSMNPs exhibited high KTZ encapsulation efficiency/capacity, optimal fluorescent property, and sustained KTZ release profile. Subsequently, 4800 nm KTZ⊂c-FSMNPs were chosen for <i>in vivo</i> studies using a mouse model, wherein the KTZ⊂c-FSMNPs were deposited intradermally <i>via</i> tattoo. The results obtained from (i) <i>in vivo</i> fluorescence imaging, (ii) high-performance liquid chromatography quantification of residual KTZ, (iii) matrix-assisted laser desorption/ionization mass spectrometry imaging mapping of KTZ distribution in intradermal regions around the tattoo site, and (iv) histology for assessment of local inflammatory responses and biocompatibility, suggest that 4800 nm KTZ⊂c-FSMNPs can serve as an effective treatment for onychomycosis

Programming Thermoresponsiveness of NanoVelcro Substrates Enables Effective Purification of Circulating Tumor Cells in Lung Cancer Patients

Unlike tumor biopsies that can be constrained by problems such as sampling bias, circulating tumor cells (CTCs) are regarded as the “liquid biopsy” of the tumor, providing convenient access to all disease sites, including primary tumor and fatal metastases. Although enumerating CTCs is of prognostic significance in solid tumors, it is conceivable that performing molecular and functional analyses on CTCs will reveal much significant insight into tumor biology to guide proper therapeutic intervention. We developed the Thermoresponsive NanoVelcro CTC purification system that can be digitally programmed to achieve an optimal performance for purifying CTCs from non-small cell lung cancer (NSCLC) patients. The performance of this unique CTC purification system was optimized by systematically modulating surface chemistry, flow rates, and heating/cooling cycles. By applying a physiologically endurable stimulation (<i>i.e.</i>, temperature between 4 and 37 °C), the mild operational parameters allow minimum disruption to CTCs’ viability and molecular integrity. Subsequently, we were able to successfully demonstrate culture expansion and mutational analysis of the CTCs purified by this CTC purification system. Most excitingly, we adopted the combined use of the Thermoresponsive NanoVelcro system with downstream mutational analysis to monitor the disease evolution of an index NSCLC patient, highlighting its translational value in managing NSCLC