Folate Ligand Research Articles

Efficient capture of circulating tumor cells with low molecular weight folate receptor-specific ligands

Retrieval of circulating tumor cells (CTC) has proven valuable for assessing a patient's cancer burden, evaluating response to therapy, and analyzing which drug might treat a cancer best. Although most isolation methods retrieve CTCs based on size, shape, or capture by tumor-specific antibodies, we explore here the use of small molecule tumor-specific ligands linked to magnetic beads for CTC capture. We have designed folic acid-biotin conjugates with different linkers for the capture of folate receptor (FR) + tumor cells spiked into whole blood, and application of the same technology to isolate FR + CTCs from the peripheral blood of both tumor-bearing mice and non-small cell lung patients. We demonstrate that folic acid linked via a rigid linker to a flexible PEG spacer that is in turn tethered to a magnetic bead enables optimal CTC retrieval, reaching nearly 100% capture when 100 cancer cells are spiked into 1 mL of aqueous buffer and ~ 90% capture when the same quantity of cells is diluted into whole blood. In a live animal model, the same methodology is shown to efficiently retrieve CTCs from tumor-bearing mice, yielding cancer cell counts that are proportional to total tumor burden. More importantly, the same method is shown to collect ~ 29 CTCs/8 mL peripheral blood from patients with non-small cell lung cancer. Since the ligand-presentation strategy optimized here should also prove useful in targeting other nanoparticles to other cells, the methods described below should have general applicability in the design of nanoparticles for cell-specific targeting.

Transferrin/folate dual-targeting Pluronic F127/poly(lactic acid) polymersomes for effective anticancer drug delivery

A novel dual-targeting Pluronic/poly(lactic acid) polymersome containing transferrin and folic acid ligands (Tf/FA-F127-PLA) has been designed to study its application in the targeted drug delivery system. Both biotin and folic acid conjugated Biotin/FA-F127-PLA polymersomes (Ps) were prepared as the precursor. The dual-targeting behaviors of Tf/FA-F127-PLA over C6 glioma cells were then fulfilled through connecting the precursor with biotinylated transferrin by using a three-step biotin-avidin technique. Paclitaxel (PTX) was loaded successfully into Biotin/FA-F127-PLA and showed a burst release followed by a slow-release process in vitro. It was also obtained that Tf/FA-F127-PLA had higher cytotoxicity and cellular uptake amount than non-targeted and single-targeted Ps did. These results could be because more PTX-loaded Tf/FA-F127-PLA Ps entered C6 cells through both FA-folate receptor (FR) and Tf-transferrin receptor (TfR) specific affinity and thus possessed the better anti-tumor ability. It was further proved that the uptake of Ps by C6 cells was through the endocytosis related to clathrin, caveolae, lysosome, etc. Furthermore, it was demonstrated that the uptake of dual-targeting Tf/FA-F127-PLA Ps by C6 cells was related to the endocytosis mediated by both FR and TfR. These findings indicated that dual-targeting Tf/FA-F127-PLA Ps could be a potential carrier in targeted drug delivery systems.

Progress of Folic Acid-Folate Receptor as Drug Carriers in Targeted Drug Delivery System

Targeted drug delivery system is an effective method for the diagnosis and treatment of cancer, it has received much attention because of its low side effects and therapeutic efficacy. Folic acid receptor is highly expressed on the surface of most cancer cells, but is low or not expressed on the surface of normal cells, and the ligand folate has a high affinity. Folic acid receptor is attached to drug carriers and can be targeted to cancer cells. This paper introduces folic acid and folate receptors, briefly describes the mechanism of action of folic acid receptor-mediated targeted drug delivery, discusses the progress on four types of folic acid-folate receptor-mediated cancer treatment: folate acid-conjugated magnetic nanoparticles, drug binding of small-molecule folic acid, folic acid receptor-bound protein, and folic acid-conjugated polysialic acid. It also analyzes the favorable points and future development trends of each treatment mechanism.

An injectable, naproxen-conjugated, supramolecular hydrogel with ultra-low critical gelation concentration-prepared from a known folate receptor ligand.

Short peptides capped on the N-terminus with aromatic groups are often able to form supramolecular hydrogels-self-assembled networks of fibrils able to trap water molecules. Typically, these hydrogelators can form stiff gels at concentrations of 0.1 to 1.0 wt%-i.e. they consist of mainly water. The properties of these soft materials mimic those of the extracellular matrix (ECM) of biological tissue and therefore they have found many biomedical uses in tissue engineering, wound healing, drug delivery, biosensing and bioprinting applications. In drug delivery strategies related to cancer therapy, injectable hydrogels can serve as a depot formulation, where a sustained release of the chemotherapeutic from near the tumour site allows reduced doses and, therefore, decreased side effects. To further target cancer cells, folic acid-conjugated hydrogels and nanostructures are often sought, to exploit the overexpression of folate receptors on cancer cells-an approach which can allow the selective cellular uptake of an encapsulated drug. In this present study, two known dipeptide folate receptor ligands (1 and 2) recently identified from a screen of a DNA-encoded compound library, were synthesised and investigated for their hydrogelation ability and cytotoxicity. Compound 1, containing a naproxen capping group, rapidly forms hydrogels at concentrations as low as 0.03 wt%-one of the lowest critical gelation concentrations (CGCs) known for a supramolecular hydrogelator. In contrast, compound 2, which contains a 3-indolepropionic acid capping group, was unable to form hydrogels under a range of conditions and concentrations, instead forming nanospheres with diameters of 0.5 μm. Hydrogels of 1 were characterised by STEM microscopy, rheology, fluorescence spectroscopy and circular dichroism. Both compounds 1 and 2 had no impact on the proliferation of kerotinocytes (HaCaT cells) at concentrations up to 100 μM. Compound 1, containing the NSAID, was tested for anti-inflammatory activity in a human cyclooxygenase-1/2 model. The rate of the release of model drug compounds from within hydrogels of 1 was also investigated.

Folic acid-conjugated mixed-ligand copper(II) complexes as promising cytotoxic agents for triple-negative breast cancers: A case study using MDA-MB-231 cell

The new mixed-ligand copper(II) complexes [Cu(FAA)(diimine)(H2O)](ClO4)2 (1–4) [FAA is folic acid-conjugated ethyl pyridyl amine; diimine is 1,10-phenanthroline (phen; 1), 5,6-dimethyl-1,10-phenanthroline (5,6-dmp; 2), 3,4,7,8-tetramethyl-1,10-phenanthroline (3,4,7,8-tmp; 3), and dipyrido-[3,2-f:2′,3′-h]-quinoxaline (dpq; 4)] were synthesized and characterized adopting appropriate analytical and spectroscopic techniques. DNA and protein binding studies showed that the complex [Cu(FAA)(5,6-dmp)(H2O)]2+ (2) has higher DNA- and protein-binding abilities than the other complexes. In the presence of the activating agent ascorbic acid, the same complex 2 caused pronounced DNA cleavage. The mechanistic study revealed that the oxidative DNA cleavage induced by complex 2 was effected through the freely diffusible hydroxyl radical; the same complex induced the highest incidence of cytotoxicity in the triple-negative breast cancer cell MDA-MB-231 (IC50 = 0.54 μM) compared to its congeners in the series, cisplatin, and the free ligand (FAA). AO/EthBr staining assay revealed induction of cell death by apoptosis. Interestingly, the complex 2 demonstrated greater selectivity toward cancer cells as revealed in only the negligible cytotoxicity to normal cells (lymphocytes), which emphasizes an important role to the cancer-targeting ligand folic acid conjugated to the Cu(II) complexes in dealing with triple-negative breast cancers.

The in vitro apoptotic effect of new zinc complex possessing folic acid and phenanthroline on cervix cancer cells

AbstractWith proper care and nursing as well as timely diagnosis and good treatment, cervical cancer is one of the most treatable forms of cancer. One of the most important cancer treatments is the use of emerging developing metal–organic complexes, which can provide a wide variety of morphologies, sizes, and properties based on different metal ions and different organic ligands. Accordingly, we reported the synthesis method, structural properties, cytotoxicity, apoptotic properties, and molecular docking analysis of the new Zn(II) complex consisting of phenanthroline and folic acid ligands. FTIR, 1H‐NMR, 13C‐NMR, and elemental analyzer determined that the synthesis of the complex was successful. The IC50 values (380 and 199 μM) were shown that the viability of HeLa cells was dependent on time of exposure and concentration of [Zn(Phen)FA] complex. Real‐time PCR clearly shows increased expression of apoptotic genes in cervical carcinoma HeLa cells and a possible relationship between Bak1/Bclx ratio and caspase‐3. Also, the key amino acids of folate receptor that can interact with the synthesized complex were identified by molecular docking analysis. Moreover, molecular electrostatic potential confirmed that carboxylate portion of FA is an electron‐rich region and can interact with Zn(Phen) to form a stable and soluble complex. All experiments confirmed that presence of FA could improve stability, cytotoxicity, apoptosis, and cellular uptake of complex in cervical carcinoma HeLa cells.

Effect of targeting ligand designation of self-assembly chitosan-poloxamer nanogels loaded Paclitacel on inhibiting MCF-7 cancer cell growth

In this study, we investigated two formulations of chitosan-Pluronic P123 with different folate ligand designation for targeted delivery of Paclitaxel (PTX), in which folic acid (FA) was directly conjugated to chitosan (FA-Cs-P123) or substituted onto P123 (Cs-P123-FA). The results showed that the FA content of Cs-P123-FA was determined at 0.71 wt/wt% which was significantly higher than that of FA-Cs-P123 (0.31 wt/wt%). Two copolymers were low critical gel concentrations (CGC). FA-Cs-P123 and Cs-P123-FA nanogels performed high PTX encapsulation efficiency reaching 95.57 ± 5.51 and 92.51 ± 6.68 wt/wt%, respectively. Transmission electron microscopy (TEM) and zeta potential analysis indicated that the PTX-loaded nanogels were spherically formed around 60 nm in diameter along with positive charge. Furthermore, the PTX release profile was slow and it was controlled by the pH of the medium. In particular, in vitro biocompatibility assays indicated that both FA-Cs-P123 and Cs-P123-FA exhibited good biological compatibility with a human foreskin fibroblast cell line and well uptake efficiency into MCF-7 cancer cells. Cs-P123-FA nanogel significantly enhanced the cytotoxicity of PTX in comparison with FA-Cs-P123. The result indicates that Cs-P123-FA nanogels with a higher decorated FA content perform a better targeting efficiency; therefore, they could have great potential application towards breast cancer treatment.

Hyaluronic acid coated Pluronic F127/Pluronic P123 mixed micelle for targeted delivery of Paclitaxel and Curcumin

The hydrophobicity of most of the anticancer drugs offers a great challenge in selecting a system for their effective transport. Here comes the importance of micelles that offers a hydrophobic core for incorporating these drugs. In this study, Hyaluronic Acid coated Pluronic mixed micelle loaded with Paclitaxel and Curcumin was designed and evaluated its anticancer activity in MCF-7 cells. Pluronic F127 (PF127) and Pluronic P123 (PP123) were taken for preparing the mixed micelles. The targeting ligand folic acid (FA) was conjugated to one end of PP123 forming FA-PP. The end hydroxyl groups of PF127 were oxidized to aldehyde groups resulted in PF-CHO. Mixed micelles were prepared from PF-CHO and FA-PP and the end aldehyde groups were used for coating the micelles with hyaluronic acid. The material was characterized using FTIR, H1NMR, DLS, FE-SEM and TEM. The coated micelles showed spherical shape with drug loading efficiency of 50.15 and 65.05% for Paclitaxel and Curcumin, respectively. In vitro drug release was studied at pH 5.5 and 7.4. Dual drug-loaded material showed higher in-vitro anticancer activity than free Paclitaxel and Curcumin. The results suggested that synthesized mixed micelle with dual drugs showed great potential for targeted delivery to MCF-7 cells.

In vitro and Microbiological Assay of Functionalized Hybrid Nanomaterials To Validate Their Efficacy in Nanotheranostics: A Combined Spectroscopic and Computational Study.

Functionalized nanoparticles reveal new frontiers in therapeutics and diagnostics, simultaneously referred to as theranostics. Functionalization of an inorganic nanoparticle (NP) with an organic ligand determines the interaction of the functionalized NPs with various cellular components, leading to the desired therapeutic effect, while diminishing adverse side effects. Apart from the therapeutic effect of the nanoparticles, other physical properties of the organic-inorganic complex (nanohybrid) including fluorescence, X-ray or MRI contrast offer diagnosis of the anomalous target cell. In this study we functionalized Mn3 O4 NPs with organic citrate (C-Mn3 O4 ) and folic acid (FA-Mn3 O4 ) ligands and investigated their antimicrobial activities using Staphylococcus hominis as a model bacteria, which can be remediated through their membrane rupture. While high-resolution transmission microscopy (HR-TEM), XRD, DLS, absorbance and fluorescence spectroscopy were used for structural characterisation of the functionalised NPs, zeta potential measurements and temperature-dependent reactive oxygen speices (ROS) generation reveal their drug action. We used high-end density functional theory (DFT) calculations to rationalise the specificity of the drug action of the NPs. Picosecond-resolved FRET studies confirm the enhanced affinity of FA-Mn3 O4 to the bacteria relative to C-Mn3 O4 , leading to enhanced antimicrobial activity. We have shown that the functionalised nanoparticles offer significant X-ray contrast in in-vitro studies, indicating the FA-Mn3 O4 NPs to be a potential theranostic agent against bacterial infection.

Dual-ligated metal organic framework as novel multifunctional nanovehicle for targeted drug delivery for hepatic cancer treatment

In the last decade, nanosized metal organic frameworks (NMOFs) have gained an increasing applicability as multifunctional nanocarriers for drug delivery in cancer therapy. However, only a limited number of platforms have been reported that can serve as an effective targeted drug delivery system (DDSs). Herein, we report rational design and construction of doxorubicin (DOX)-loaded nanoscale Zr (IV)-based NMOF (NH2-UiO-66) decorated with active tumor targeting moieties; folic acid (FA), lactobionic acid (LA), glycyrrhetinic acid (GA), and dual ligands of LA and GA, as efficient multifunctional DDSs for hepatocellular carcinoma (HCC) therapy. The success of modification was exhaustively validated by various structural, thermal and microscopic techniques. Biocompatibility studies indicated the safety of pristine NH2-UiO-66 against HSF cells whereas DOX-loaded dual-ligated NMOF was found to possess superior cytotoxicity against HepG2 cells which was further confirmed by flow cytometry. Moreover, fluorescence microscopy was used for monitoring cellular uptake in comparison to the non-ligated and mono-ligated NMOF. Additionally, the newly developed dual-ligated NMOF depicted a pH-responsiveness towards the DOX release. These findings open new avenues in designing various NMOF-based DDSs that actively target hepatic cancer to achieve precise therapy.

The role of folic acid in inducing of apoptosis by zinc(II) complex in ovary and cervix cancer cells.

Herein, the synthesis, structure, binding affinity, cytotoxicity, and apoptotic properties of the new Zn(II) complex composed of folic acid and bipyridine ligands are reported. Because folic acid has the ability to target cancer cells directly, so it can play a role in targeted drug delivery of the complex and be useful to distinguish normal cells from cancerous. After characterization of Zinc complex utilizing FTIR, EA, and NMR, the results of MTT assay were shown that viability levels of two FR-positive cell lines (HeLa and Ovcar-3) are dependent on time and concentration of [Zn(bpy)FA], whereas, did not show a significant effect on FR-negative cell lines (A549). Also, Real-time PCR revealed that the presence of FA can influence the expression of apoptosis in cervical carcinoma HeLa cells while cisplatin alone doesn't have the ability to trigger apoptosis. Furthermore, the experimental results were evaluated using pharmacophore modeling and molecular docking analysis. Finally, the stability of the Zn(II) complex was surveyed using quantum mechanical studies.

Retraction Note to: Design and surface modification of potential luminomagnetic nanocarriers for biomedical applications

Targeted delivery of therapeutics possesses the potential to localize therapeutic agents to a specific tissue as a mechanism to enhance treatment efficacy and mitigate side effects. Moeities that combine imaging and therapeutic modalities in a single macromolecular construct may confer advantages in the development and applications of nanomedicine. Here is an insight into the synthesis of luminomagnetic (luminescent and magnetic, simultaneously) nanocarriers of ZnO:Fe, synthesized by a simple co-precipitation method and surface modified by the ligand folate. This functionalized luminomagnetic nanocarrier system is a bioconjugation approach which combines the specificity of folate receptors on cancer cells with the excellent optical and magnetic properties of the nanoparticles so as to develop biocompatible molecular imaging agents, drug delivery systems, and hyperthermia agents. The vibrating sample magnetometer (VSM) studies showed clear hysteresis loops having coercivity 5.1 mT with corresponding magnetization of remanence 7.6 × 10−3 emu/g, indicating strong magnetic character of the samples. X-ray diffraction (XRD) and transmission electron microscopy (TEM) measurements show that these nanoparticles are spherical with 6–9 nm size and hence are quite appropriate for in vivo applications as well. The immobilization of folic acid was confirmed by fourier transform infrared (FTIR) analysis. All these properties make these luminomagnetic nanocarriers one of the most feasible candidates for folate receptor-mediated biomedical applications.

A folate-targeted PEGylated cyclodextrin-based nanoformulation achieves co-delivery of docetaxel and siRNA for colorectal cancer

Docetaxel (DTX) is a chemotherapeutic agent used for a range of cancers, but it has little activity against colorectal cancer (CRC). However, combination therapy with other therapeutic agents is a potential strategy to enhance the efficacy of DTX in CRC treatment. The nuclear factor-κB (NF-κB) signaling pathway is implicated in a variety of malignancies (e.g., CRC), and the blockade of NF-κB may increase the sensitivity of cancer cells to chemotherapy. The application of small interference RNA (siRNA) to inhibit the translation of complementary mRNA has demonstrated the potential for cancer gene therapy. In this study, an amphiphilic cationic cyclodextrin (CD) nanoparticle modified with PEGylated folate (FA; a ligand to target folate receptor on CRC) has been developed for co-delivery of DTX and siRNA (against the RelA, a subunit of NF-κB) in the treatment of CRC. The resultant co-formulation (CD.DTX.siRelA.PEG-FA) achieved cell-specific uptake indicating the function of the folate targeting ligand. The CD.DTX.siRelA.PEG-FA nanoparticle enhanced the apoptotic effect of DTX with the downregulation of RelA expression, which significantly retarded the growth of CRC in mice, without causing significant toxicity. These results suggest that the FA-targeted PEGylated CD-based co-formulation provides a promising strategy for combining DTX and siRNA in treating CRC.

(Invited) Multifunctional Carbon Nanodots for Theranostic Applications

Carbon nanodots are a form of carbon that is attracting a lot of attention, as they are considered promising nanomaterials for future clinical translation. Carbon nanodots combine numerous characteristics including high photostability, low cytotoxicity, and superior biocompatibility. We have conceived and synthesised multifunctional carbon nanodots with deep-red emission properties through their controlled chemical modification using folic acid ligand (Figure). These carbon nanodots, endowed of a high colloidal stability and an enhanced luminescence, are suitable for targeted intracellular production of reactive oxygen species by laser irradiation leading to efficient cancer cell death [1]. In addition, we have modified carbon nanodots with a chelating agent for gadolinium. These nanodots showed a better magnetic resonance relaxivity than commercial MRI agents, resulting potential clinical tools as MRI/fluorescence dually functional imaging probes.[1] Ji, D.-K.; Reina,G.; Guo,S.; Eredia,M.; Samorì, P.; Ménard-Moyon, C.; BiancoA. Controlled Functionalization of Red-emissive Carbon Nanodots for Targeted Intracellular Production of Reactive Oxygen Species. Nanoscale Horizons 2020, 5, 1240-1249. DOI:10.1039/D0NH00300J Figure 1

Renal-targeting peptide-microRNA nanocomplex for near IR imaging and therapy of renal ischemia/reperfusion injury

Renal ischemia-reperfusion injury (RI/R) is one of the main causes of acute renal injury and a common clinical disease with high morbidity and mortality. It is of great significance to deliver microRNAs (miRNAs) to cells and in vivo to realize gene regulation and treatment of related diseases. In this study, we reported that the nanocomplex FMN-17 could realize both therapeutic and functional monitoring simultaneously in vivo and in vitro. The nanocomplex comprised a cationic cell-penetrating peptide nona-arginine, a targeting ligand folic acid, a caspase-3 responsive moiety, and a Cy imaging moiety. The nanocomplex FMN-17 has been shown to deliver miR-17-5p efficiently and selectively into HK-2 cells and tissues. Treatment of HK-2 cells with the nanocomplex significantly increased the miR-17-5p level and inhibited apoptosis, as evident by reducing the expression of active caspase-3 and reactive oxygen species. Uptake of FMN-17 in vivo alleviated renal tissue injury by histological assessment. In summary, we designed and synthesized a new miRNA delivery system with high transfection efficiency, good therapeutic effect, and near-infrared imaging in renal ischemia/reperfusion injury.

A phthalocyanine-based self-assembled nanophotosensitizer for efficient in vivo photodynamic anticancer therapy

To develop highly efficient photosensitizers for photodynamic therapy, herein a zinc(II) phthalocyanine-folate conjugate (PcN-FA) used to construct an activatable nanophotosensitizer (NanoPcN-FA) through a facile self-assembly. The self-assembled nanophotosensitizer (NanoPcN) without folate-modification was used as a negative control. After self-assembly, the photoactivities of NanoPcN-FA was quenched. The in vitro studies showed that NanoPcN-FA could be taken in by folate-receptor (FR)-positive SKOV3 cells and activated in the cells. It also exhibited slightly higher photocytotoxicity against SKOV3 cells than NanoPcN. Moreover, the competitive assay confirmed that the cellular uptake of NanoPcN-FA was through a FR-mediated process. Finally, the in vivo results indicated that NanoPcN-FA could target tumor tissue of S180 rat ascitic tumor-bearing mice due to the folic acid (FA) ligand, leading to a highly efficient antitumor photodynamic efficacy with the tumor inhibition rate of 95%.

Phenol-Boronic surface functionalization of gold nanoparticles; to induce ROS damage while inhibiting the survival mechanisms of cancer cells

The natural phenolic molecule caffeic acid, show promising effects on biological systems as an anti/pro-oxidant, anti-cancer, and anti-inflammatory agent. In nanoparticle functionalization designs, most organic nanoparticle coatings are utilized only for their ability to carry chemotherapeutics and targeting ligand. In this study, UV-light and auto-oxidation polymerization of caffeic acid on top of as-prepared gold nanoparticles was utilized to bring about a 5 nm multifunctional coating. The resulting polycaffeic acid (PCA) coating was used to conjugate both boronic acid containing compounds, chemotherapeutic bortezomib (BTZ) and cancer targeting ligand folate, while inducing mitochondrial reactive oxygen species that can damage intracellular proteins and DNA. This complements the drug payload, bortezomib’s cell survival inhibition properties. The drug, targeting ligand, and coating complexation are all pH cleavable under acidic pH condition (<5.0) which can be found in a tumor and endosomal microenvironment. The in vitro and in vivo experiments demonstrated cancer cytotoxicity and tumor inhibiting properties of the developed nanomedicine.

Bioorthogonal chemistry in metal clusters: a general strategy for the construction of multifunctional probes for bioimaging in living cells and in vivo.

Multifunctional bioimaging probes based on metal clusters have multiple characteristics of metal clusters and functional conjugates, and their development has broad application prospects in the fields of biomedical imaging and tumor diagnosis. However, current bioconjugation methods on metal clusters are time-consuming and have low reaction efficiency, which hinders the construction of bioimaging probes with multifunctional components. Here, we report a concise and promising design strategy to realize the simple and efficient introduction of functional conjugates through bioorthogonal reactions based on azido-functionalized metal clusters. Based on this strategy, taking the probe FA-CuC@BSA-Cy5 as an example, we demonstrated the design of a copper cluster-based multifunctional near-infrared (NIR) fluorescent probe and its real-time imaging application in vivo. Through the strain-promoted azide-alkyne cycloaddition (SPAAC) reaction, the tumor-specific targeting ligand folic acid (FA) and fluorophore (Cy5) can be chemically conjugated to azido-functionalized CuC@BSA-N3 quickly and efficiently under biocompatible conditions. The prepared probe showed numerous advantages of metal clusters, including good stability, ultra-small particle size and low toxicity and rapid renal clearance. At the same time, FA-modified FA-CuC@BSA-Cy5 can specifically target KB cells with high FR expression, and in vivo fluorescence imaging shows higher tumor accumulation. The construction of the azido functional metal cluster platform can be extended to various metal clusters with functional probes and prodrugs, thereby providing more promising candidates for future medical diagnoses.

NIR Photoregulated Theranostic System Based on Hexagonal-Phase Upconverting Nanoparticles for Tumor-Targeted Photodynamic Therapy and Fluorescence Imaging.

Although photodynamic therapy (PDT) is an effective, minimally invasive therapeutic modality with advantages in highly localized and specific tumor treatments, large and deep-seated cancers within the body cannot be successfully treated due to low transparency to visible light. To improve the therapeutic efficiency of tumor treatment in deep tissue and reduce the side effects in normal tissue, this study developed a near-infrared (NIR)-triggered upconversion nanoparticle (UCNP)-based photosensitizer (PS) carrier as a new theranostics system. The NaYF4:Yb/Er UCNPs were synthesized by a hydrothermal method, producing nanoparticles of a uniformly small size (≈20 nm) and crystalline morphology of the hexagonal phase. These UCNPs were modified with folic acid-conjugated biocompatible block copolymers through a bidentate dihydrolipoic acid linker. The polymer modified hexagonal phase UCNPs (FA-PEAH-UCNPs) showed an improved dispersibility in the aqueous solution and strong NIR-to-vis upconversion fluorescence. The hydrophobic PS, pheophorbide a (Pha), was then conjugated to the stable vectors. Moreover, these UCNP-based Pha carriers containing tumor targeting folic acid ligands exhibited the significantly enhanced cellular uptake efficiency as well as PDT treatment efficiency. These results suggested that this system could extend the excitation wavelength of PDT to the NIR region and effectively improve therapeutic efficiency of PSs.

Shortwave infrared emitting multicolored nanoprobes for biomarker-specific cancer imaging in vivo

BackgroundThe ability to detect tumor-specific biomarkers in real-time using optical imaging plays a critical role in preclinical studies aimed at evaluating drug safety and treatment response. In this study, we engineered an imaging platform capable of targeting different tumor biomarkers using a multi-colored library of nanoprobes. These probes contain rare-earth elements that emit light in the short-wave infrared (SWIR) wavelength region (900–1700 nm), which exhibits reduced absorption and scattering compared to visible and NIR, and are rendered biocompatible by encapsulation in human serum albumin. The spectrally distinct emissions of the holmium (Ho), erbium (Er), and thulium (Tm) cations that constitute the cores of these nanoprobes make them attractive candidates for optical molecular imaging of multiple disease biomarkers.MethodsSWIR-emitting rare-earth-doped albumin nanocomposites (ReANCs) were synthesized using controlled coacervation, with visible light-emitting fluorophores additionally incorporated during the crosslinking phase for validation purposes. Specifically, HoANCs, ErANCs, and TmANCs were co-labeled with rhodamine-B, FITC, and Alexa Fluor 647 dyes respectively. These Rh-HoANCs, FITC-ErANCs, and 647-TmANCs were further conjugated with the targeting ligands daidzein, AMD3100, and folic acid respectively. Binding specificities of each nanoprobe to distinct cellular subsets were established by in vitro uptake studies. Quantitative whole-body SWIR imaging of subcutaneous tumor bearing mice was used to validate the in vivo targeting ability of these nanoprobes.ResultsEach of the three ligand-functionalized nanoprobes showed significantly higher uptake in the targeted cell line compared to untargeted probes. Increased accumulation of tumor-specific nanoprobes was also measured relative to untargeted probes in subcutaneous tumor models of breast (4175 and MCF-7) and ovarian cancer (SKOV3). Preferential accumulation of tumor-specific nanoprobes was also observed in tumors overexpressing targeted biomarkers in mice bearing molecularly-distinct bilateral subcutaneous tumors, as evidenced by significantly higher signal intensities on SWIR imaging.ConclusionsThe results from this study show that tumors can be detected in vivo using a set of targeted multispectral SWIR-emitting nanoprobes. Significantly, these nanoprobes enabled imaging of biomarkers in mice bearing bilateral tumors with distinct molecular phenotypes. The findings from this study provide a foundation for optical molecular imaging of heterogeneous tumors and for studying the response of these complex lesions to targeted therapy.