Dendrimers in combination with natural products and analogues as anti-cancer agents

Overcoming multidrug resistance in cancer: Recent progress in nanotechnology and new horizons

Multidrug resistance (MDR), defined as the ability of cancer cells to gain resistance to both conventional and novel chemotherapy agents, is an important barrier in treating malignancies. Initially, it was discovered that cellular pumps dependent on ATP were the cause of resistance to chemotherapy, and further studies have found that other mechanisms such as increased metabolism of drugs, decreased drug entry, and defective apoptotic pathways are involved in this process. MDR has been the focus of numerous initiatives and countless studies have been undertaken to better understand MDR and formulate strategies to overcome its effects. The current review highlights various nano-drug delivery systems including polymeric/solid lipid/mesoporous silica/metal nanoparticles, dendrimers, liposomes, micelles, and nanostructured lipid carriers to overcome the mechanism of MDR. Nanoparticles are novel gateways to enhance the therapeutic efficacy of anticancer agents at the target site of action due to their tumor-targeting abilities, which can limit the unwanted systemic effects of chemotherapy agents and also reduce drug resistance. Additionally, other innovative strategies including RNA interference as a biological process used to inhibit or silence specific gene expression, natural products as MDR modulators with little systemic toxic effects, which interfere with the functions of proteins involved in drug efflux, and physical approaches such as combination of conventional drug administration with thermal/ultrasound/photodynamic strategies are also highlighted.

Carboxyl-, sulfonyl-, and phosphate-terminal dendrimers as a nanoplatform with lymph node targeting

The development of drug delivery vehicles to cancer and/or immune cells in lymph nodes is important for cancer diagnosis, therapy, and immunotherapy. We previously reported that anionic carboxyl-terminal dendrimers were accumulated in lymph nodes. In this study, three anionic dendrimers with carboxyl-, sulfonyl-, and phosphate-terminal groups were prepared to examine the lymph node targeting and the association with immune cells in the lymph nodes. These anionic dendrimers were accumulated in the lymph node by intradermal injection. Although the carboxyl- and sulfonyl-terminal dendrimers were diffused from the injection site, the phosphate-terminal dendrimers were mostly retained. The phosphate-terminal dendrimer was recognized by the macrophages, dendritic cells, and B cells in the lymph node, whereas the carboxyl- and sulfonyl-terminal dendrimers were not. Our results show that these anionic dendrimers were accumulated in the lymph node where the association with immune cells could be controlled by the terminal structure of the dendrimer. The phosphate-terminal dendrimer can be used as a nanoplatform for the delivery of some bioactive molecules to some immune cells, including B cells, in the lymph node.

New insights into the blue intrinsic fluorescence of oxidized PAMAM dendrimers considering their use as bionanomaterials

The fluorescence intensity of oxidized PAMAM dendrimers is not only dependent on the number of HASLs in the dendrimer scaffold (i.e., on dendrimer generation), but also on the rigidification suffered by the dendrimer due to the acidic environment.

New insights into the blue intrinsic fluorescence of oxidized PAMAM dendrimers considering their use as bionanomaterials

The fluorescence intensity of oxidized PAMAM dendrimers is not only dependent on the number of HASLs in the dendrimer scaffold (i.e., on dendrimer generation), but also on the rigidification suffered by the dendrimer due to the acidic environment.

Advanced Nanovehicles-Enabled Delivery Systems of Epigallocatechin Gallate for Cancer Therapy

Epigallocatechin gallate (EGCG) is the most abundant polyphenolic constituent derived from green tea extract, which has demonstrated versatile bioactivities in combating cardiovascular diseases, neurodegenerative diseases, diabetes, and cancer. In light of its anticancer activity, increasing attention has been paid to developing potent strategies involving EGCG in cancer chemotherapy. However, the poor bioavailability and stability of EGCG limits its effectiveness and practicality in real biomedical applications. To overcome this drawback, nanotechnology-facilitated drug delivery systems have been introduced and intensively explored to enhance the bioavailability and therapeutic efficacy of EGCG in cancer treatments and interventions. This review briefly discusses the anticancer mechanisms of EGCG, and then summarizes recent advances in engineering nanovehicles for encapsulating and delivering EGCG toward cancer therapy. In addition, we also highlight successful integrations of EGCG delivery with other chemotherapies, gene therapies, and phototherapies in one nanostructured entity for a combination therapy of cancers. To conclude, the current challenges and future prospects of the nanovehicle-based transportation systems of EGCG for cancer therapy are also discussed.

A dual drug-based hyperbranched polymer with methotrexate and chlorambucil moieties for synergistic cancer chemotherapy

Dual drug-based hyperbranched polymer micelles simultaneously containing methotrexate and chlorambucil were constructed for synergistic cancer chemotherapy.

Straightforward synthesis of gold nanoparticles by adding water to an engineered small dendrimer

A small water-soluble phosphorus-containing dendrimer was engineered for the complexation of gold(I) and for its reduction under mild conditions. Gold nanoparticles were obtained as colloidal suspensions simply and only when the powdered form of this dendrimer was dissolved in water, as shown by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) analyses. The dendrimers acted simultaneously as mild reducers and as nanoreactors, favoring the self-assembly of gold atoms and promoting the growth and stabilization of isolated gold nanoparticles. Thus, an unprecedented method for the synthesis of colloidal suspensions of water-soluble gold nanoparticles was proposed in this work.

Oral Mucositis in Pediatric Oncology Patients: A Nested Case-Control to a Prospective Cohort

Abstract This study aimed to evaluate the factors associated with the occurrence of severe oral mucositis (SOM) in pediatric oncology patients during the chemotherapeutic treatment. This is a nested case-control to a prospective cohort that monitored 105 patients for 10 consecutive weeks after the beginning of the chemotherapy treatment. Logistic regression was used to identify the factors associated with SOM, by group of malignancy (hematologic or solid tumors) (Sig.=5%). To patients with hematologic tumors were found factors associated with SOM in two weeks of treatment: in the 6th week (increase in frequency of chemotherapy doses (OR=3.02)) and in the 7th week (female sex (OR=21.28); and increase in frequency of chemotherapy doses (OR=2.51)); and to patients with solid tumors were found factors associated with SOM in five weeks of treatment: in the 1st week (female sex (OR=14.43); age increase (OR=1.24)); in the 2nd week (Miscellany (OR=6.39)); in the 5th week (Antimetabolites (OR=17.44); Miscellany (OR=45.42); and platelets reduction (OR=1.12)); in the 6th week (creatinine increase (OR=1.63)); and in the 7th week (creatinine increase (OR=2.39)). For patients with hematologic tumors, to be female, and the increase in the frequency of chemotherapy doses increased the risk for SOM and for patients with solid tumors, to be female, the increase in age and in level blood concentration of creatinine, the reduction in number of platelets and the use of chemotherapy with miscellany and antimetabolites agents were associated with an increase in risk for occurrence of SOM.

Ecliptasaponin A induces apoptosis through the activation of ASK1/JNK pathway and autophagy in human lung cancer cells

Background

Non-small cell lung cancer (NSCLC) is one of the causes of carcinomas mortality worldwide. Ecliptasaponin A (ES), a natural product extracted from the plant known as Eclipta prostrata, has been reported as an anti-cancer drug against various cancer cell lines. However, the exact mechanisms of ES have not yet been fully characterized.

Methods

Numerous studies have been done to support that ES has a powerful inhibiting effect on the growth of cancers via the activation of apoptosis and autophagy. To explore the underlying mechanisms of anti-cancer and investigate the relationships of the apoptosis and autophagy, we used apoptosis signal-regulating kinase 1 (ASK1) inhibitor (GS-4997), c-Jun N-terminal kinase (JNK) inhibitor (SP600125), and autophagy inhibitor [chloroquine (CQ) and 3-methyladenine (3-MA)].

Results

ES could potently suppress cell viability and induces apoptotic cell death of human lung cancer cells H460 and H1975. ES activated apoptosis via ASK1/JNK pathway, GS-4997 and SP600125 can attenuated these effects. Furthermore, ES could triggered autophagy in lung cancer cell lines, and the autophagy inhibitor 3-MA and CQ reversed ES-induced apoptosis in H460 and H1975 cells. Furthermore, SP600125 can inhibit autophagy.

Conclusions

This study showed that ES induces apoptosis in human lung cancer cells by triggering enhanced autophagy and ASK1/JNK pathway, which may thus be a promising agent against lung cancer.

Synthesis, characterization, anti-proliferative properties and DNA binding of benzochromene derivatives: Increased Bax/Bcl-2 ratio and caspase-dependent apoptosis in colorectal cancer cell line

3-Amino-1-aryl-1H-benzo[f]chromene-2-carbonitrile derivatives were synthesized from three-component reaction of arylaldehyde, malononitrile and 2-naphthol in the presence of 1, 4-bis(4-ferrocenylbutyl)piperazine as a new catalyst. Cytotoxic potencies of the compounds were tested on HT-29 cells. 3-Amino-1-(4-fluorophenyl)-1H-benzo[f]chromene-2-carbonitrile (4c) was more active among these compounds and was selected for further studies. Apoptosis was investigated by acridine orange/ethidium bromide (AO/EtBr) double staining and flow cytometry. The qRT-PCR was used to analyze the expression of pro- and anti-apoptotic genes. The binding attributes of 4c with calf thymus DNA (ctDNA) was examined using multi-spectroscopic measurements. We found that 4c had potent cytotoxic activity against HT-29 cells with an IC₅₀ value of 60 µM through induction of cell cycle arrest in the sub-G1 phase and apoptosis. RT-PCR analysis demonstrated down-regulation of Bcl-2 expression, while the expression of Bax, caspase-3, -8 and -9 genes was up-regulated in HT-29 cells incubated with 4c compared with control cells. These studies revealed that 4c interacts with DNA through groove binding mode with the intrinsic binding constant (K_b) of 3 × 10² M^-1. Thus, 4c is a valuable candidate for further evaluation as a new series of potent chemotherapeutic family in colon cancer treatment.

Acidity-responsive shell-sheddable camptothecin-based nanofibers for carrier-free cancer drug delivery

Small molecular prodrugs that self-assemble into nanoparticles have many advantages over commonly studied nanomedicines based upon nanoscale carriers such as liposomes, micelles and polymeric nanoparticles. These carrier-free nanodrugs exhibit favorable nanoproperties without the help of a nanocarrier, and they have many unique merits, such as a simple synthetic procedure, well-defined structure and high drug loading capacity. To date, most of these carrier-free nanodrugs have been spherical and very few nonspherical nanodrugs have been synthesized and studied. Herein, we report a camptothecin (CPT) prodrug that self-assembles into nanofibers. These carrier-free CPT nanofibers have a width of approximately one hundred nanometers and a length of several micrometers. The cellular uptake and tumor penetration behaviour of these nanofibers were observed by time-lapse video microscopy. These nanofibers can rapidly enter cancer cells by penetrating the cell membrane, gradually dissolve intracellularly and efficiently release the active drug. Coating the surface of these nanofibers with a pH-responsive PEG layer improves the stability of these nanofibers and shields their positive charge to minimize nonspecific interactions. These pH-responsive nanofibers are sheddable in the acidic tumor microenvironment and deliver carried cargoes deep into tumors. Our findings demonstrate that small molecular CPT prodrugs that form nanofibers are efficient for cancer drug delivery.

Inhibitory Effects of Ginsenoside Ro on the Growth of B16F10 Melanoma via Its Metabolites

Ginsenoside Ro (Ro), a major saponin derived and isolated from Panax ginseng C.A. Meyer, exerts multiple biological activities. However, the anti-tumour efficacy of Ro remains unclear because of its poor in vitro effects. In this study, we confirmed that Ro has no anti-tumour activity in vitro. We explored the anti-tumour activity of Ro in vivo in B16F10 tumour-bearing mice. The results revealed that Ro considerably suppressed tumour growth with no significant side effects on immune organs and body weight. Zingibroside R1, chikusetsusaponin IVa, and calenduloside E, three metabolites of Ro, were detected in the plasma of Ro-treated tumour-bearing mice and showed excellent anti-tumour effects as well as anti-angiogenic activity. The results suggest that the metabolites play important roles in the anti-tumour efficacy of Ro in vivo. Additionally, the haemolysis test demonstrated that Ro has good biocompatibility. Taken together, the findings of this study demonstrate that Ro markedly suppresses the tumour growth of B16F10-transplanted tumours in vivo, and its anti-tumour effects are based on the biological activity of its metabolites. The anti-tumour efficacy of these metabolites is due, at least in part, to its anti-angiogenic activity.

Metal-based phosphorus dendrimers as novel nanotherapeutic strategies to tackle cancers: A concise overview

Several metal-based phosphorus dendrimers were prepared. The first series developed by us was the Cu(II) series. In this series, the most potent is the third generation-Cu(II) showing original mechanism of action with activation of the pro-apoptotic Bax protein. To our knowledge, it is the first example of nanoparticles displaying Bax protein activation and then cell death through apoptosis process. Interestingly, this dendritic-Cu(II) complex showed synergistic effect with doxorubicin. Based on these interesting anti-proliferative activities, we developed Au(III)-conjugated phosphorus dendrimers. The most potent is the third generation-Au(III) dendrimer which represents also a new and promising first-in-class anti-proliferative agent against both solid and liquid tumor cell lines. Then, in order to analyze the influence of the metal moiety distribution of Cu(II) and Au(III) on the surface of dendrimers, mix Cu(II)-Au(III)-conjugated phosphorus dendrimers were also prepared and tested as anti-proliferative agents. This article is categorized under: Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Current trends and challenges in cancer management and therapy using designer nanomaterials

Nanotechnology has the potential to circumvent several drawbacks of conventional therapeutic formulations. In fact, significant strides have been made towards the application of engineered nanomaterials for the treatment of cancer with high specificity, sensitivity and efficacy. Tailor-made nanomaterials functionalized with specific ligands can target cancer cells in a predictable manner and deliver encapsulated payloads effectively. Moreover, nanomaterials can also be designed for increased drug loading, improved half-life in the body, controlled release, and selective distribution by modifying their composition, size, morphology, and surface chemistry. To date, polymeric nanomaterials, metallic nanoparticles, carbon-based materials, liposomes, and dendrimers have been developed as smart drug delivery systems for cancer treatment, demonstrating enhanced pharmacokinetic and pharmacodynamic profiles over conventional formulations due to their nanoscale size and unique physicochemical characteristics. The data present in the literature suggest that nanotechnology will provide next-generation platforms for cancer management and anticancer therapy. Therefore, in this critical review, we summarize a range of nanomaterials which are currently being employed for anticancer therapies and discuss the fundamental role of their physicochemical properties in cancer management. We further elaborate on the topical progress made to date toward nanomaterial engineering for cancer therapy, including current strategies for drug targeting and release for efficient cancer administration. We also discuss issues of nanotoxicity, which is an often-neglected feature of nanotechnology. Finally, we attempt to summarize the current challenges in nanotherapeutics and provide an outlook on the future of this important field.

Multiple pathways for natural product treatment of Parkinson's disease: A mini review

BACKGROUND

It is established that natural medicines for Parkinson's disease (PD) provide an antioxidant activity in preventing dopaminergic neurons from degeneration. However, the underlying and related molecular details remain poorly understood.

METHODS AND AIM

We review published in vitro and rodent studies of natural products in PD models with the aim to identify common molecular pathways contributing to the treatment efficacy. Commonly regulated genes were identified through the systemic literature search and further analyzed from a network perspective.

FINDINGS

Approximately thirty different types of natural products have been investigated for their ability to regulate protein density and gene activity in various experimental systems. Most were found to attenuate neurotoxin-induced regulations. Three common PD pathways are involved. The most studied pathway was neuronal development/anti-apoptosis consisting of Bax/Bcl-2, caspases 3/9, and MAPK signaling. Another well studied was anti-inflammation comprising iNOS, nNOS, Nrf2/ARE, cytokines, TNFα, COX2 and MAPK signaling. The third pathway referred to dopamine transmission modulation with upregulated VMAT2, DAT, NURR1 and GDNF levels. To date, HIPK2, a conserved serine/threonine kinase and transcriptional target of Nrf2 in an anti-apoptosis signaling pathway, is the first protein identified as the direct binding target of a natural product (ZMHC).

IMPLICATIONS

Natural products may utilize multiple and intercellular pathways at various steps to prevent DA neurons from degeneration. Molecular delineation of the mechanisms of actions is revealing new, perhaps combinational therapeutic approaches to stop the progression of DA degeneration.

Dendrimer-Enabled Therapeutic Antisense Delivery Systems as Innovation in Medicine

Antisense oligonucleotide (AON)-based therapies concern the treatment for genetic disorders or infections such as a range of neurodegenerative and neuromuscular diseases and have shown benefits in animal models and patients. Nevertheless, successes in the clinic are still strongly limited by unfavorable biodistribution and poor cellular uptake of AONs. Dendrimer macromolecules are synthetically accessible and consist of a core with repeated iterations (named branches) surrounding this core, and on the periphery functional groups which can be modified for ligand attachment. The generations of these branched nanoparticles are based on the number of branches emanating from the core with layered architectures. Dendrimers show promise in several biomedical applications based on their tunable surface modifications allowing the adjustment of their in vivo behavior related to biocompatibility and pharmacokinetic parameters. Dendrimers can be used as nanocarriers of various types of drugs including AONs or nanodrugs. As nanocarriers, polycationic dendrimers can complex multiple negatively charged DNA oligonucleotides on their surface and form stable complexes to promote internalization into the cells based on a good cell membrane affinity. These nanocarriers complexing antisense oligonucleotides must be stable enough to reach the cellular target, but with adequate in vivo global clearance, and have good pharmacokinetic (PK) and pharmacodynamic (PD) profiles. This Review was designed to analyze the development of AONs carried by polycationic and polyanionic (few example) dendrimers. This Review strongly supports the idea that dendrimers, with adequate modulation of their terminal groups, could be used to carry AONs in cells.

On-surface synthesis of planar dendrimers via divergent cross-coupling reaction

Dendrimers are homostructural and highly branched macromolecules with unique dendritic effects and extensive use in multidisciplinary fields. Although thousands of dendrimers have been synthesized in solution, the on-surface synthetic protocol for planar dendrimers has never been explored, limiting the elucidation of the mechanism of dendritic effects at the single-molecule level. Herein, we describe an on-surface synthetic approach to planar dendrimers, in which exogenous palladium is used as a catalyst to address the divergent cross-coupling of aryl bromides with isocyanides. This reaction enables one aryl bromide to react with two isocyanides in sequential steps to generate the divergently grown product composed of a core and two branches with high selectivity and reactivity. Then, a dendron with four branches and dendrimers with eight or twelve branches in the outermost shell are synthesized on Au(111). This work opens the door for the on-surface synthesis of various planar dendrimers and relevant macromolecular systems.

Although many strategies exist to synthesize dendrimers in solution, the synthesis of planar dendrimers on a surface has proven challenging. Here, the authors produce planar dendrimers through a divergent on-surface cross-coupling reaction between one aryl bromide and two isocyanides, which enables the growth of branches from a single reactive site.

Anticancer Effects of Five Biflavonoids from Ginkgo Biloba L. Male Flowers In Vitro

Ginkgo biloba L., an ancient dioecious gymnosperm, is now cultivated worldwide for landscaping and medical purposes. A novel biflavonoid—amentoflavone 7′′-O-β-d-glucopyranoside (1)—and four known biflavonoids were isolated and identified from the male flowers of Ginkgo. The anti-proliferative activities of five biflavonoids were evaluated on different cancer lines. Bilobetin (3) and isoginkgetin (4) exhibited better anti-proliferative activities on different cancer lines. Their effects were found to be cell-specific and in a dose and time dependent manner for the most sensitive HeLa cells. The significant morphological changes validated their anticancer effects in a dose-dependent manner. They were capable of arresting the G2/M phase of the cell cycle, inducing the apoptosis of HeLa cells dose-dependently and activating the proapoptotic protein Bax and the executor caspase-3. Bilobetin (3) could also inhibit the antiapoptotic protein Bcl-2. These might be the mechanism underlying their anti-proliferation. In short, bilobetin (3) and isoginkgetin (4) might be the early lead compounds for new anticancer agents.

Integrating nanomedicine into clinical radiotherapy regimens

While the advancement of clinical radiotherapy was driven by technological innovations throughout the 20th century, continued improvement relies on rational combination therapies derived from biological insights. In this review, we highlight the importance of combination radiotherapy in the era of precision medicine. Specifically, we survey and summarize the areas of research where improved understanding in cancer biology will propel the field of radiotherapy forward by allowing integration of novel nanotechnology-based treatments.

Effect of increasing liver blood flow on nanodrug clearance by the liver for enhanced antitumor therapy

A norepinephrine-loaded nano-system can serve as an effective auxiliary agent for reducing nanodrug clearance by the liver and enhancing tumor therapy.

Synthesis and photophysical properties of novel pyrene–metalloporphyrin dendritic systems

Energy transfer studies were performed on a series of new pyrene–metalloporphyrin (Zn, Cu, Mg and Mn) dendritic constructs.

Dendrimers for pulmonary delivery: current perspectives and future challenges

Dendrimers and dendrimer-based delivery systems are potential biomedicines in the rapidly growing field of nanomedicine.

A star-shaped molecularly imprinted polymer derived from polyhedral oligomeric silsesquioxanes with improved site accessibility and capacity for enantiomeric separation via capillary electrochromatography

A star-shaped molecularly imprinted coating was prepared starting from octavinyl-modified polyhedral oligomeric silsesquioxanes (Ov-POSS). It possesses a relatively open structure and has good site accessibility and a larger capacity even at lower cross-linking. The imprinted coating was prepared from S-amlodipine (S-AML) as the template and analyte, Ov-POSS as the cross-linker, and methacrylic acid as the functional monomer. The preparation and chromatographic parameters were optimized, including ratio of template to functional monomer, apparent cross-linking degree, pH value, ACN content and salt concentration in the mobile phase. The best resolution in enantiomer separation by means of capillary electrochromatography reaches a value of 33. A good recognition ability (α = 2.60) was obtained and the column efficiency for S-AML was 54,000 plates m^-1. The use of Ov-POSS as a cross-linker significantly improves the column capacity and thus the detection sensitivity. The results show that Ov-POSS is an effective cross-linker for the preparation of imprinted polymers with good accessibility and large capacity. Graphical abstract Schematic presentation of the preparation of star-shaped imprinted polymer using octavinyl-modified polyhedral oligomeric silsesquioxanes (Ov-POSS) and by using methacrylic acid (MAA) as functional monomer. The best enantiometric resolution (33) for amlodipine (AML) can be achieved in capillary chromatography (CEC).

Structure optimization of dendritic lipopeptide based gene vectors with the assistance from molecular dynamic simulation

Disulfide modified lipopeptide assemblies with an arginine-rich dendritic periphery provide a promising platform for effective gene transfer. Dendritic arginine peptides that mimic the cell-penetrating peptides of a virus envelope are vital for complexation, interaction with physical barriers, and final gene release. Here, we report three lipopeptides with different-generation dendritic peripheries (R₁LS, R₂LS and R₃LS), each of which contains a dioleoyl-l-lysinate hydrophobic tail. Such molecules were proven to self-assemble in aqueous solution with different morphologies, sizes, and surface zeta potentials. R₂LS and R₃LS assemblies showed spherical and spindle shapes with zeta potentials of 27.2 and 32.8 mV, respectively. They exhibited complete condensation of pDNA at a low N/P ratio, while R₁LS assemblies displayed a fiber pattern with a relatively low electric potential of 10.9 mV with poor DNA binding ability. In a cellular viability experiment, R₁LS and R₂LS have no significant cytotoxicity even at high dosage, while R₃LS showed conspicuous toxicity. As a gene vector, R₂LS presented high gene transfection efficiency either in the presence or the absence of serum, which was 58.7% greater than liposome 2000 and PEI in the condition of 10% fetal bovine serum for HeLa cells. While R₃LS showed good results just without serum and R₁LS was unserviceable in all situations. Moreover, molecular dynamic simulation was exploited to analyze the kinestate of the signal molecule and the interactions of multiple molecules, which could assist us in better understanding the experimental phenomena. The simulation results indicated that the R₂LS molecule has better flexibility, which was favorable for interaction with the cell membrane. And it could generate tight integration in self-assembly while R₁LS and R₃LS assemblies have a large molecular interval, which led to a controllable release of cargos for R₂LS in a reductive environment. In summary, the generation of the dendrimer in lipopeptides is vital for the gene transfer effect. For optimization, it is necessary to study the structure-function relationship, and molecular dynamic simulation is an effective strategy for screening the molecular structure and even for predicting experimental results.

Platelets and their biomimetics for regenerative medicine and cancer therapies

Platelets, circulating blood cells derived from megakaryocytes, play a key role in various physical activities, including coagulation, hemostasis, the body's innate immune response, and cancer metastasis. By taking advantage of their key traits, researchers have developed strategies to exploit platelets and platelet-mimicking nanoassemblies to treat a number of conditions, including wounds, cancers, and bacterial infections. Compared to traditional polymer, lipsosome, and inorganic nanoparticles-based delivery systems, platelets and platelet-mimicking vehicles hold many advantages. Among these are their enhanced circulation time, their large volumes and surface areas for drug loading or conjugation, and their inherent ability to target some diseases. In this review, we will highlight the recent progress made in the development of disease-targeting platelets- and platelet-mimicking-vehicles as therapeutic platforms.

Multifunctional Dendrimer-Entrapped Gold Nanoparticles Conjugated with Doxorubicin for pH-Responsive Drug Delivery and Targeted Computed Tomography Imaging

Novel theranostic nanocarriers exhibit a desirable potential to treat diseases based on their ability to achieve targeted therapy while allowing for real-time imaging of the disease site. Development of such theranostic platforms is still quite challenging. Herein, we present the construction of multifunctional dendrimer-based theranostic nanosystem to achieve cancer cell chemotherapy and computed tomography (CT) imaging with targeting specificity. Doxorubicin (DOX), a model anticancer drug, was first covalently linked onto the partially acetylated poly(amidoamine) dendrimers of generation 5 (G5) prefunctionalized with folic acid (FA) through acid-sensitive cis-aconityl linkage to form G5·NHAc-FA-DOX conjugates, which were then entrapped with gold (Au) nanoparticles (NPs) to create dendrimer-entrapped Au NPs (Au DENPs). We demonstrate that the prepared DOX-Au DENPs possess an Au core size of 2.8 nm, have 9.0 DOX moieties conjugated onto each dendrimer, and are colloid stable under different conditions. The formed DOX-Au DENPs exhibit a pH-responsive release profile of DOX because of the cis-aconityl linkage, having a faster DOX release rate under a slightly acidic pH condition than under a physiological pH. Importantly, because of the coexistence of targeting ligand FA and Au core NPs as a CT imaging agent, the multifunctional DOX-loaded Au DENPs afford specific chemotherapy and CT imaging of FA receptor-overexpressing cancer cells. The constructed DOX-conjugated Au DENPs hold a promising potential to be utilized for simultaneous chemotherapy and CT imaging of various types of cancer cells.

Energy Transfer in Dendritic Systems Having Pyrene Peripheral Groups as Donors and Different Acceptor Groups

In this feature article, a specific overview of resonance energy transfer (FRET) in dendritic molecules was performed. We focused mainly on constructs bearing peripheral pyrene groups as donor moieties using different acceptor groups, such as porphyrin, fullerene C60, ruthenium-bipyridine complexes, and cyclen-core. We have studied the effect of all the different donor-acceptor pairs in the energy transfer efficiency (FRET). In all cases, high FRET efficiency values were observed.

Doxorubicin-Conjugated PAMAM Dendrimers for pH-Responsive Drug Release and Folic Acid-Targeted Cancer Therapy

We present here the development of multifunctional doxorubicin (DOX)-conjugated poly(amidoamine) (PAMAM) dendrimers as a unique platform for pH-responsive drug release and targeted chemotherapy of cancer cells. In this work, we covalently conjugated DOX onto the periphery of partially acetylated and folic acid (FA)-modified generation 5 (G5) PAMAM dendrimers through a pH-sensitive cis-aconityl linkage to form the G5.NHAc-FA-DOX conjugates. The formed dendrimer conjugates were well characterized using different methods. We show that DOX release from the G5.NHAc-FA-DOX conjugates follows an acid-triggered manner with a higher release rate under an acidic pH condition (pH = 5 or 6, close to the acidic pH of tumor microenvironment) than under a physiological pH condition. Both in vitro cytotoxicity evaluation and cell morphological observation demonstrate that the therapeutic activity of dendrimer-DOX conjugates against cancer cells is absolutely related to the DOX drug released. More importantly, the FA conjugation onto the dendrimers allowed a specific targeting to cancer cells overexpressing FA receptors (FAR), and allowed targeted inhibition of cancer cells. The developed G5.NHAc-FA-DOX conjugates may be used as a promising nanodevice for targeted cancer chemotherapy.

PAMAM dendrimers as efficient drug and gene delivery nanosystems for cancer therapy

Drug delivery systems for cancer chemotherapy are employed to improve the effectiveness and decrease the side-effects of highly toxic drugs. Most chemotherapy agents have indiscriminate cytotoxicity that affects normal, as well as cancer cells. To overcome these problems, new more efficient nanosystems for drug delivery are increasingly being investigated. Polyamidoamine (PAMAM) dendrimers are an example of a versatile and reproducible type of nanocarrier that can be loaded with drugs, and modified by attaching target-specific ligands that recognize receptors that are over-expressed on cancer cells. PAMAM dendrimers with a high density of cationic charges display electrostatic interactions with nucleic acids (DNA, siRNA, miRNA, etc.), creating dendriplexes that can preserve the nucleic acids from degradation. Dendrimers are prepared by conducting several successive "generations" of synthetic reactions so their size can be easily controlled and they have good uniformity. Dendrimers are particularly well-suited to co-delivery applications (simultaneous delivery of drugs and/or genes). In the current review, we discuss dendrimer-based targeted delivery of drugs/genes and co-delivery systems mainly for cancer therapy.

Cellular Uptake Behaviors of Rigidity-Tunable Dendrimers

Understanding of the interaction between cells and nanoparticles (NPs) is critical. Despite numerous attempts to understand the effect of several parameters of NPs on their cellular uptake behaviors, such as size, shape, surface chemistry, etc., limited information is available regarding NP rigidity. Herein, we investigate the effect of rigidity on cellular uptake behaviors of NPs, using generation 5 poly(amidoamine) dendrimer as a model. By harnessing the abundant inner cavity, their rigidity could be effectively regulated by forming size-tunable gold NPs. The NPs thus formed were well characterized and displayed similar hydrodynamic size, surface potential, fluorescence intensity, and distinct rigidity (owing to differences in the size of the Au core). Flow cytometry analysis revealed a positive correlation between NP rigidity and cellular uptake of NPs. Confocal microscopic evaluation revealed that the entrapped gold NPs may affect the intracellular localization of the internalized dendrimers. The present findings can potentially guide the preparation of suitable NPs for biomedical applications.

Loading IR820 Using Multifunctional Dendrimers with Enhanced Stability and Specificity

Cyanine dyes are promising candidates in biomedical applications. Although various delivery systems have been developed to enhance their properties, their dendrimer-based delivery systems are seldom investigated. Herein, amine-terminated generation 5 poly(amidoamine) (G5.NH₂) dendrimers and new indocyanine green (IR820) dyes were chosen as models to study the loading ability of dendrimers for cyanine dynes. G5.NH₂ dendrimers were pre-modified with arginine-glycine-aspartic (RGD) peptides, poly(ethylene glycol) chains, and acetyl groups to be endowed with cancer cell specificity and biocompatibility. The formed Ac-PR dendrimers were used to load IR820, followed by thorough characterization. The loaded number of IR820 was estimated to be 6.7 per dendrimer. The stability of IR820 was improved through dendrimer loading, which was proved by their UV-vis spectra under different kinds of storage conditions. In addition, the formed Ac-PR dendrimers can retain the loaded IR820 effectively. Their cytocompatibility was desirable under the studied conditions. Their cellular uptake behaviors were demonstrated to be enhanced by RGD modification, showing concentration-, co-incubation time-, and αvβ₃ integrin receptor-dependent properties, displaying a cytoplasm-location. The findings from this work demonstrated the versatile loading and delivery capacity of dendrimers for near-infrared (NIR) dyes, providing fundamental data for the development of dendrimer/NIR dye systems for biomedical applications, especially for cancer theranostic applications.

Distributions: The Importance of the Chemist's Molecular View for Biological Materials

Characterization of materials with biological applications and assessment of physiological effects of therapeutic interventions are critical for translating research to the clinic and preventing adverse reactions. Analytical techniques typically used to characterize targeted nanomaterials and tissues rely on bulk measurement. Therefore, the resulting data represent an average structure of the sample, masking stochastic (randomly generated) distributions that are commonly present. In this Perspective, we examine almost 20 years of work our group has done in different fields to characterize and control distributions. We discuss the analytical techniques and statistical methods we use and illustrate how we leverage them in tandem with other bulk techniques. We also discuss the challenges and time investment associated with taking such a detailed view of distributions as well as the risks of not fully appreciating the extent of heterogeneity present in many systems. Through three case studies showcasing our research on conjugated polymers for drug delivery, collagen in bone, and endogenous protein nanoparticles, we discuss how identification and characterization of distributions, i.e., a molecular view of the system, was critical for understanding the observed biological effects. In all three cases, data would have been misinterpreted and insights missed if we had only relied upon spatially averaged data. Finally, we discuss how new techniques are starting to bridge the gap between bulk and molecular level analysis, bringing more opportunity and capacity to the research community to address the challenges of distributions and their roles in biology, chemistry, and the translation of science and engineering to societal challenges.

Design, Synthesis, and Biological Evaluations of Asymmetric Bow-Tie PAMAM Dendrimer-Based Conjugates for Tumor-Targeted Drug Delivery

A unique asymmetric bow-tie poly(amidoamine) (PAMAM) dendrimer (ABTD) scaffold was designed and developed as a well-defined macromolecular carrier for tumor-targeted drug delivery. The ABTD scaffold in this study consists of a G3-half-dendron (G3-HD) unit and a G1-half-dendron (G1-HD) unit, bearing thiol moiety in each unit and a bis(maleimide) linker unit, which undergo sequential thiol-maleimide coupling to assemble the scaffold. This assembly methodology is applicable to all other combinations of different generations of PAMAM dendrimers. In the prototype ABTD in this study, 16 biotin moieties were tethered to the G3-HD unit and 4 payloads (new-generation taxoid) to the G1-HD via a self-immolative linker to form an ABTD-tumor-targeting conjugate (ABTD-TTC-1). Two other ABTD-TTCs were synthesized, wherein the G1-HD unit was tethered to a fluorescence-labeled taxoid or to a fluorescent probe. These three ABTD-TTCs were constructed by using a common key ABTD 6 bearing a terminal acetylene group in the G1-HD unit, which was fully characterized as a single molecule by high-resolution mass spectrometry and NMR despite its high molecular weight (M_w: 12 876). Then, the click reaction was employed to couple ABTD 6 with a small-molecule payload or fluorescence probe unit bearing a terminal azide moiety. ABTD-TTC-3, as a surrogate of ABTD-TTC-2, showed substantially enhanced internalization into two cancer cell lines via receptor-mediated endocytosis, attributed to multibinding effect. ABTD-TTC-1 exhibited a remarkable selectivity to cancer cells (1400-7500 times) compared to human normal cells, which demonstrates the salient feature and bright prospect of the ABTD-based tumor-targeted drug-delivery system.

Dendrimeric Antigens for Drug Allergy Diagnosis: A New Approach for Basophil Activation Tests

Dendrimeric Antigens (DeAns) consist of dendrimers decorated with multiple units of drug antigenic determinants. These conjugates have been shown to be a powerful tool for diagnosing penicillin allergy using in vitro immunoassays, in which they are recognized by specific IgE from allergic patients. Here we propose a new diagnostic approach using DeAns in cellular tests, in which recognition occurs through IgE bound to the basophil surface. Both IgE molecular recognition and subsequent cell activation may be influenced by the tridimensional architecture and size of the immunogens. Structural features of benzylpenicilloyl-DeAn and amoxicilloyl-DeAn (G2 and G4 PAMAM) were studied by diffusion Nuclear Magnetic Resonance (NMR) experiments and are discussed in relation to molecular dynamics simulation (MDS) observations. IgE recognition was clinically evaluated using the basophil activation test (BAT) for allergic patients and tolerant subjects. Diffusion NMR experiments, MDS and cellular studies provide evidence that the size of the DeAn, its antigen composition and tridimensional distribution play key roles in IgE-antigen recognition at the effector cell surface. These results indicate that the fourth generation DeAns induce a higher level of basophil activation in allergic patients. This approach can be considered as a potential complementary diagnostic method for evaluating penicillin allergy.

A novel high-capacity immunoadsorbent with PAMAM dendritic spacer arms by click chemistry

A novel immunoadsorbent with polyamidoamine dendritic spacer arms was prepared. Click chemistry can improve the reaction selectivity between the ligands and the support matrix under mild reaction conditions. The designed and prepared immunoadsorbent exhibits excellent adsorption for IgG. The IgG adsorption capacity of Sep-G3-His is superior to those of Sep-triazole-His and protein A immunoadsorbents.