Selective aggregation of PAMAM dendrimer nanocarriers and PAMAM/ZnPc nanodrugs on human atheromatous carotid tissues: a photodynamic therapy for atherosclerosis

Photodynamic Therapy for Atherosclerosis

Atherosclerosis, which currently contributes to 31% of deaths globally, is of critical cardiovascular concern. Current diagnostic tools and biomarkers are limited, emphasizing the need for early detection. Lifestyle modifications and medications form the basis of treatment, and emerging therapies such as photodynamic therapy are being developed. Photodynamic therapy involves a photosensitizer selectively targeting components of atherosclerotic plaques. When activated by specific light wavelengths, it induces localized oxidative stress aiming to stabilize plaques and reduce inflammation. The key advantage lies in its selective targeting, sparing healthy tissues. While preclinical studies are encouraging, ongoing research and clinical trials are crucial for optimizing protocols and ensuring long-term safety and efficacy. The potential combination with other therapies makes photodynamic therapy a versatile and promising avenue for addressing atherosclerosis and associated cardiovascular disease. The investigations underscore the possibility of utilizing photodynamic therapy as a valuable treatment choice for atherosclerosis. As advancements in research continue, photodynamic therapy might become more seamlessly incorporated into clinical approaches for managing atherosclerosis, providing a blend of efficacy and limited invasiveness.

Recent Advances for Dynamic-Based Therapy of Atherosclerosis

Atherosclerosis (AS) is a chronic inflammatory disease, which may lead to high morbidity and mortality. Currently, the clinical treatment strategy for AS is administering drugs and performing surgery. However, advanced therapy strategies are urgently required because of the deficient therapeutic effects of current managements. Increased number of energy conversion-based organic or inorganic materials has been used in cancer and other major disease treatments, bringing hope to patients with the development of nanomedicine and materials. These treatment strategies employ specific nanomaterials with specific own physiochemical properties (external stimuli: light or ultrasound) to promote foam cell apoptosis and cholesterol efflux. Based on the pathological characteristics of vulnerable plaques, energy conversion-based nano-therapy has attracted increasing attention in the field of anti-atherosclerosis. Therefore, this review focuses on recent advances in energy conversion-based treatments. In addition to summarizing the therapeutic effects of various techniques, the regulated pathological processes are highlighted. Finally, the challenges and prospects for further development of dynamic treatment for AS are discussed.

Angiopep-2 Grafted PAMAM Dendrimers for the Targeted Delivery of Temozolomide: In Vitro and In Vivo Effects of PEGylation in the Management of Glioblastoma Multiforme

The present study was aimed to synthesize, characterize, and evaluate the angiopep-2 grafted PAMAM dendrimers (Den, G 3.0 NH₂) with and without PEGylation for the targeted and better delivery approach of temozolomide (TMZ) for the management of glioblastoma multiforme (GBM). Den-ANG and Den-PEG₂-ANG conjugates were synthesized and characterized by ¹H NMR spectroscopy. The PEGylated (TMZ@Den-PEG₂-ANG) and non-PEGylated (TMZ@Den-ANG) drug loaded formulations were prepared and characterized for particle size, zeta potential, entrapment efficiency, and drug loading. An in vitro release study at physiological (pH 7.4) and acidic pH (pH 5.0) was performed. Preliminary toxicity studies were performed through hemolytic assay in human RBCs. MTT assay, cell uptake, and cell cycle analysis were performed to evaluate the in vitro efficacy against GBM cell lines (U87MG). Finally, the formulations were evaluated in vivo in a Sprague-Dawley rat model for pharmacokinetics and organ distribution analysis. The ¹H NMR spectra confirmed the conjugation of angiopep-2 to both PAMAM and PEGylated PAMAM dendrimers, as the characteristic chemical shifts were observed in the range of 2.1 to 3.9 ppm. AFM results revealed that the surface of Den-ANG and Den-PEG₂-ANG conjugates were rough. The particle size and zeta potential of TMZ@Den-ANG were observed to be 229.0 ± 17.8 nm and 9.06 ± 0.4 mV, respectively, whereas the same for TMZ@Den-PEG₂-ANG were found to be 249.6 ± 12.9 nm and 10.9 ± 0.6 mV, respectively. The entrapment efficiency of TMZ@Den-ANG and TMZ@Den-PEG₂-ANG were calculated to be 63.27 ± 5.1% and 71.48 ± 4.3%, respectively. Moreover, TMZ@Den-PEG₂-ANG showed a better drug release profile with a controlled and sustained pattern at PBS pH 5.0 than at pH 7.4. The ex vivo hemolytic study revealed that TMZ@Den-PEG₂-ANG was biocompatible in nature as it showed 2.78 ± 0.1% hemolysis compared to 4.12 ± 0.2% hemolysis displayed by TMZ@Den-ANG. The outcomes of the MTT assay inferred that TMZ@Den-PEG₂-ANG possessed maximum cytotoxic effects against U87MG cells with IC₅₀ values of 106.62 ± 11.43 μM (24 h) and 85.90 ± 9.12 μM (48 h). In the case of TMZ@Den-PEG₂-ANG, the IC₅₀ values were reduced by 2.23-fold (24 h) and 1.36-fold (48 h) in comparison to pure TMZ. The cytotoxicity findings were further confirmed by significantly higher cellular uptake of TMZ@Den-PEG₂-ANG. Cell cycle analysis of the formulations suggested that the PEGylated formulation halts the cell cycle at G2/M phase with S-phase inhibition. In the in vivo studies, the half-life (t_1/2) values of TMZ@Den-ANG and TMZ@Den-PEG₂-ANG were enhanced by 2.22 and 2.76 times, respectively, than the pure TMZ. After 4 h of administration, the brain uptake values of TMZ@Den-ANG and TMZ@Den-PEG₂-ANG were found to be 2.55 and 3.35 times, respectively, higher than that of pure TMZ. The outcomes of various in vitro and ex vivo experiments promoted the use of PEGylated nanocarriers for the management of GBM. Angiopep-2 grafted PEGylated PAMAM dendrimers can be potential and promising drug carriers for the targeted delivery of antiglioma drugs directly to the brain.

Effect of PEGylation on drug uptake, biodistribution, and tissue toxicity of efavirenz-ritonavir loaded PAMAM G4 dendrimers

The present investigations aimed to compare the efficiency of PAMAM G4 (PG4) and PEGylated PAMAM G4 (PPG4) dendrimers as novel nanocarriers for the treatment of HIV-1. Synthesized PG4 and PPG4 dendrimers were confirmed by electrospray ionization and particle size with its morphology. The anti-human immunodeficiency virus (HIV) drug efavirenz (EFV) with a booster dose of ritonavir (RTV) was encapsulated into PG4 and PPG4 formerly noted as PG4ER and PPG4ER, respectively. Further, evaluated for dendrimers mediated solubilization, drug release, cytotoxicity, drug uptake, plasma, and tissue pharmacokinetics, and histopathology. PG4ER and PPG4ER both promoted a prolonged release of EFV in weakly acidic pH 4 up to 84 h and 132 h, respectively. The results of the cytotoxicity assay and drug uptake study showed that PPG4ER was safe and biocompatible up to 12.5 µg/ml. The plasma pharmacokinetic profile of EFV and RTV was significantly increased by PPG4ER with prolonged t_1/2 up to three times as compared to free EFV-RTV and PG4ER. Histopathological analysis showed remarkably lower tissue toxicity in PPG4ER as compared to free EFV-RTV. Therefore, overall data suggested that PPG4 has a great potential for prolonged release of EFV and RTV with enhanced bioavailability and lower toxicity.

The Fractal Viewpoint of Tumors and Nanoparticles

Even though the promising therapies against cancer are rapidly improved, the oncology patients population has seen exponential growth, placing cancer in 5th place among the ten deadliest diseases. Efficient drug delivery systems must overcome multiple barriers and maximize drug delivery to the target tumors, simultaneously limiting side effects. Since the first observation of the quantum tunneling phenomenon, many multidisciplinary studies have offered quantum-inspired solutions to optimized tumor mapping and efficient nanodrug design. The property of a wave function to propagate through a potential barrier offer the capability of obtaining 3D surface profiles using imaging of individual atoms on the surface of a material. The application of quantum tunneling on a scanning tunneling microscope offers an exact surface roughness mapping of tumors and pharmaceutical particles. Critical elements to cancer nanotherapeutics apply the fractal theory and calculate the fractal dimension for efficient tumor surface imaging at the atomic level. This review study presents the latest biological approaches to cancer management based on fractal geometry.

Advances in imaging and treatment of atherosclerosis based on organic nanoparticles

Atherosclerosis, a systemic chronic inflammatory disease, can lead to thrombosis and vascular occlusion, thereby inducing a series of serious vascular diseases. Currently, distinguishing unstable plaques early and achieving more effective treatment are the two main clinical concerns in atherosclerosis. Organic nanoparticles have great potential in atherosclerotic imaging and treatment, showing superior biocompatibility, drug-loading capacity, and synthesis. This article illustrates the process of atherosclerosis onset and the key targeted cells, then systematically summarizes recent progress made in organic nanoparticle-based imaging of different types of targeted cells and therapeutic methods for atherosclerosis, including optical and acoustic-induced therapy, drug delivery, gene therapy, and immunotherapy. Finally, we discuss the major impediments that need to be addressed in future clinical practice. We believe this article will help readers to develop a comprehensive and in-depth understanding of organic nanoparticle-based atherosclerotic imaging and treatment, thus advancing further development of anti-atherosclerosis therapies.

Analyzing siRNA Concentration, Complexation and Stability in Cationic Dendriplexes by Stem-Loop Reverse Transcription-qPCR

RNA interference (RNAi) is a powerful therapeutic approach for messenger RNA (mRNA) level regulation in human cells. RNAi can be triggered by small interfering RNAs (siRNAs) which are delivered by non-viral carriers, e.g., dendriplexes. siRNA quantification inside carriers is essential in drug delivery system development. However, current siRNA measuring methods either are not very sensitive, only semi-quantitative or not specific towards intact target siRNA sequences. We present a novel reverse transcription real-time PCR (RT-qPCR)-based application for siRNA quantification in drug formulations. It enables specific and highly sensitive quantification of released, uncomplexed target siRNA and thus also indirect assessment of siRNA stability and concentration inside dendriplexes. We show that comparison with a dilution series allows for siRNA quantification, exclusively measuring intact target sequences. The limit of detection (LOD) was 4.2 pM (±0.2 pM) and the limit of quantification (LOQ) 77.8 pM (±13.4 pM) for uncomplexed siRNA. LOD and LOQ of dendriplex samples were 31.6 pM (±0 pM) and 44.4 pM (±9.0 pM), respectively. Unspecific non-target siRNA sequences did not decrease quantification accuracy when present in samples. As an example of use, we assessed siRNA complexation inside dendriplexes with varying nitrogen-to-phosphate ratios. Further, protection of siRNA inside dendriplexes from RNase A degradation was quantitatively compared to degradation of uncomplexed siRNA. This novel application for quantification of siRNA in drug delivery systems is an important tool for the development of new siRNA-based drugs and quality checks including drug stability measurements.

Nanotechnology, Nanomedicine, and the Kidney

The kidneys are vital organs performing several essential functions. Their primary function is the filtration of blood and the removal of metabolic waste products as well as fluid homeostasis. Renal filtration is the main pathway for drug removal, highlighting the importance of this organ to the growing field of nanomedicine. The kidneys (i) have a key role in the transport and clearance of nanoparticles (NPs), (ii) are exposed to potential NPs’ toxicity, and (iii) are the targets of diseases that nanomedicine can study, detect, and treat. In this review, we aim to summarize the latest research on kidney-nanoparticle interaction. We first give a brief overview of the kidney’s anatomy and renal filtration, describe how nanoparticle characteristics influence their renal clearance, and the approaches taken to image and treat the kidney, including drug delivery and tissue engineering. Finally, we discuss the future and some of the challenges faced by nanomedicine.

Use of Half-Generation PAMAM Dendrimers (G0.5–G3.5) with Carboxylate End-Groups to Improve the DACHPtCl2 and 5-FU Efficacy as Anticancer Drugs

The DACHPtCl2 compound (trans-(R,R)-1,2-diaminocyclohexanedichloroplatinum(II)) is a potent anticancer drug with a broad spectrum of activity and is less toxic than oxaliplatin (trans-l-diaminocyclohexane oxalate platinum II), with which it shares the active metal fragment DACHPt. Nevertheless, due to poor water solubility, its use as a chemotherapeutic drug is limited. Here, DACHPtCl2 was conjugated, in a bidentate form, with half-generation PAMAM dendrimers (G0.5–G3.5) with carboxylate end-groups, and the resulting conjugates were evaluated against various types of cancer cell lines. In this way, we aimed at increasing the solubility and availability at the target site of DACHPt while potentially reducing the adverse side effects. DNA binding assays showed a hyperchromic effect compatible with DNA helix’s disruption upon the interaction of the metallodendrimers and/or the released active metallic fragments with DNA. Furthermore, the prepared DACHPt metallodendrimers presented cytotoxicity in a wide set of cancer cell lines used (the relative potency regarding oxaliplatin was in general high) and were not hemotoxic. Importantly, their selectivity for A2780 and CACO-2 cancer cells with respect to non-cancer cells was particularly high. Subsequently, the anticancer drug 5-FU was loaded in a selected metallodendrimer (the G2.5COO(DACHPt)16) to investigate a possible synergistic effect between the two drugs carried by the same dendrimer scaffold and tested for cytotoxicity in A2780cisR and CACO-2 cancer cell lines. This combination resulted in IC50 values much lower than the IC50 for 5-FU but higher than those found for the metallodendrimers without 5-FU. It seems, thus, that the metallic fragment-induced cytotoxicity dominates over the cytotoxicity of 5-FU in the set of considered cell lines.

Use of Half-Generation PAMAM Dendrimers (G0.5-G3.5) with Carboxylate End-Groups to Improve the DACHPtCl2 and 5-FU Efficacy as Anticancer Drugs

The DACHPtCl₂ compound (trans-(R,R)-1,2-diaminocyclohexanedichloroplatinum(II)) is a potent anticancer drug with a broad spectrum of activity and is less toxic than oxaliplatin (trans-l-diaminocyclohexane oxalate platinum II), with which it shares the active metal fragment DACHPt. Nevertheless, due to poor water solubility, its use as a chemotherapeutic drug is limited. Here, DACHPtCl₂ was conjugated, in a bidentate form, with half-generation PAMAM dendrimers (G0.5-G3.5) with carboxylate end-groups, and the resulting conjugates were evaluated against various types of cancer cell lines. In this way, we aimed at increasing the solubility and availability at the target site of DACHPt while potentially reducing the adverse side effects. DNA binding assays showed a hyperchromic effect compatible with DNA helix's disruption upon the interaction of the metallodendrimers and/or the released active metallic fragments with DNA. Furthermore, the prepared DACHPt metallodendrimers presented cytotoxicity in a wide set of cancer cell lines used (the relative potency regarding oxaliplatin was in general high) and were not hemotoxic. Importantly, their selectivity for A2780 and CACO-2 cancer cells with respect to non-cancer cells was particularly high. Subsequently, the anticancer drug 5-FU was loaded in a selected metallodendrimer (the G2.5COO(DACHPt)₁₆) to investigate a possible synergistic effect between the two drugs carried by the same dendrimer scaffold and tested for cytotoxicity in A2780cisR and CACO-2 cancer cell lines. This combination resulted in IC₅₀ values much lower than the IC₅₀ for 5-FU but higher than those found for the metallodendrimers without 5-FU. It seems, thus, that the metallic fragment-induced cytotoxicity dominates over the cytotoxicity of 5-FU in the set of considered cell lines.

Recent advances in nanomaterials for therapy and diagnosis for atherosclerosis

Atherosclerosis is a chronic inflammatory disease driven by lipid accumulation in arteries, leading to narrowing and thrombosis. It affects the heart, brain, and peripheral vessels and is the leading cause of mortality in the United States. Researchers have strived to design nanomaterials of various functions, ranging from non-invasive imaging contrast agents, targeted therapeutic delivery systems to multifunctional nanoagents able to target, diagnose, and treat atherosclerosis. Therefore, this review aims to summarize recent progress (2017-now) in the development of nanomaterials and their applications to improve atherosclerosis diagnosis and therapy during the preclinical and clinical stages of the disease.

Metalloporphyrins in Medicine: From History to Recent Trends

The history of metalloporphyrins dates back more than 200 years ago. Metalloporphyrins are excellent catalysts, capable of forming supramolecular systems, participate in oxygen photosynthesis, transport, and used as contrast agents or superoxide dismutase mimetics. Today, metalloporphyrins represent complexes of conjugated π-electron system and metals from the entire periodic system. However, the effect of these compounds on living systems has not been fully understood, and researchers are exploring the properties of metalloporphyrins thereby extending their further application. This review provides an overview of the variety of metalloporphyrins that are currently used in different medicine fields and how metalloporphyrins became the subject of scientists' interest. Currently, metalloporphyrins utilization has expanded significantly, which gave us an opprotunuty to summarize recent progress in metalloporphyrins derivatives and prospects of their application in the treatment and diagnosis of different diseases.

Nanoparticle-Based Approaches towards the Treatment of Atherosclerosis

Atherosclerosis, being an inflammation-associated disease, represents a considerable healthcare problem. Its origin remains poorly understood, and at the same time, it is associated with extensive morbidity and mortality worldwide due to myocardial infarctions and strokes. Unfortunately, drugs are unable to effectively prevent plaque formation. Systemic administration of pharmaceuticals for the inhibition of plaque destabilization bears the risk of adverse effects. At present, nanoscience and, in particular, nanomedicine has made significant progress in both imaging and treatment of atherosclerosis. In this review, we focus on recent advances in this area, discussing subjects such as nanocarriers-based drug targeting principles, approaches towards the treatment of atherosclerosis, utilization of theranostic agents, and future prospects of nanoformulated therapeutics against atherosclerosis and inflammatory diseases. The focus is placed on articles published since 2015 with additional attention to research completed in 2019-2020.

Applications and Limitations of Dendrimers in Biomedicine

Biomedicine represents one of the main study areas for dendrimers, which have proven to be valuable both in diagnostics and therapy, due to their capacity for improving solubility, absorption, bioavailability and targeted distribution. Molecular cytotoxicity constitutes a limiting characteristic, especially for cationic and higher-generation dendrimers. Antineoplastic research of dendrimers has been widely developed, and several types of poly(amidoamine) and poly(propylene imine) dendrimer complexes with doxorubicin, paclitaxel, imatinib, sunitinib, cisplatin, melphalan and methotrexate have shown an improvement in comparison with the drug molecule alone. The anti-inflammatory therapy focused on dendrimer complexes of ibuprofen, indomethacin, piroxicam, ketoprofen and diflunisal. In the context of the development of antibiotic-resistant bacterial strains, dendrimer complexes of fluoroquinolones, macrolides, beta-lactamines and aminoglycosides have shown promising effects. Regarding antiviral therapy, studies have been performed to develop dendrimer conjugates with tenofovir, maraviroc, zidovudine, oseltamivir and acyclovir, among others. Furthermore, cardiovascular therapy has strongly addressed dendrimers. Employed in imaging diagnostics, dendrimers reduce the dosage required to obtain images, thus improving the efficiency of radioisotopes. Dendrimers are macromolecular structures with multiple advantages that can suffer modifications depending on the chemical nature of the drug that has to be transported. The results obtained so far encourage the pursuit of new studies.

Conjugation of Phthalocyanine Photosensitizer with Poly(amidoamine) Dendrimer: Improved Solubility, Disaggregation and Photoactivity Against HepG2 Cells

OBJECTIVE

To improve solubility and to reduce aggregation, ZnPcC4 was conjugated to a third-generation poly-amidoamine dendrimer with amino end group (G3-PAMAM-NH2), which acts as a novel photodynamic therapy (PDT) drug carrier system.

METHODS

The phthalocyanines were synthesized by construction reaction. The nano drug was obtained from the conjugation of ZnPcC4 to G3-PAMAM-NH2, using EDC and NHS as coupling agents. The ZnPcC4@G3-PAMAM-NH2 conjugation was characterized by UV-Vis and MS. The 1O2 quantum yield of ZnPcC4@G3-PAMAM-NH2 in water was measured by the chemiluminescence method. The in vitro PDT responses of the studied photosensitizers were studied in hepatocellular carcinoma cell line HepG2 by MTT assay.

RESULTS

At ZnPcC4/G3-PAMAM-NH2 raw ratio of 100/1, the ZnPcC4 conjugate had improved solubility and reduced aggregation tendency in aqueous solution. At this optimum molar ratio, ZnPcC4- G3-PAMAM-NH2 inhibited HepG2 cells, with a half-maximal inhibitory concentration of 1.67 µg/mL upon infrared light exposure. The controls, including dark conditions, or media as well as G3-PAMAM-NH2 exposure, exhibited no inhibitory response.

CONCLUSION

The conjugation of phthalocyanine photosensitizer ZnPcC4 to poly-amidoamine dendrimer G3-PAMAM-NH2 improved the PDT outcomes, in which the optimized binding ratio of ZnPcC4 to G3-PAMAM-NH2 was 6:1.

Entropy and Random Walk Trails Water Confinement and Non-Thermal Equilibrium in Photon-Induced Nanocavities

Molecules near surfaces are regularly trapped in small cavitations. Molecular confinement, especially water confinement, shows intriguing and unexpected behavior including surface entropy adjustment; nevertheless, observations of entropic variation during molecular confinement are scarce. An experimental assessment of the correlation between surface strain and entropy during molecular confinement in tiny crevices is difficult because strain variances fall in the nanometer scale. In this work, entropic variations during water confinement in 2D nano/micro cavitations were observed. Experimental results and random walk simulations of water molecules inside different size nanocavitations show that the mean escaping time of molecular water from nanocavities largely deviates from the mean collision time of water molecules near surfaces, crafted by 157 nm vacuum ultraviolet laser light on polyacrylamide matrixes. The mean escape time distribution of a few molecules indicates a non-thermal equilibrium state inside the cavity. The time differentiation inside and outside nanocavities reveals an additional state of ordered arrangements between nanocavities and molecular water ensembles of fixed molecular length near the surface. The configured number of microstates correctly counts for the experimental surface entropy deviation during molecular water confinement. The methodology has the potential to identify confined water molecules in nanocavities with life science importance.

A near-infrared laser and H2O2 activated bio-nanoreactor for enhanced photodynamic therapy of hypoxic tumors

Synergistic photodynamic therapy of mitochondria-targeting and O₂ self-supply can be achieved in a sample near-infrared laser and H₂O₂ activated bio-nanoreactor.

Glycine-Poly-L-Lactic Acid Copolymeric Nanoparticles for the Efficient Delivery of Bortezomib

PURPOSE

Bortezomib (BTZ) is a proteasome inhibitor used for multiple myeloma and mantle cell lymphoma treatment. BTZ's aqueous in solubility is the main hindrance in its successful development as a commercial formulation. The main objective of the present study is to develop and characterize folic acid-glycine-poly-L-lactic acid (FA-Gly₄-PLA) based nanoformulation (NPs) to improve solubility and efficacy of BTZ.

METHODS

BTZ loaded FA-Gly₄-PLA NPs were prepared and characterized for size, zeta potential, in vitro studies such as release, kinetics modeling, hemolytic toxicity, and cell line-based studies (Reactive Oxygen Species: ROS and cytotoxicity).

RESULTS

BTZ loaded NPs (BTZ-loaded FA-Gly₄-PLA) and blank NPs (FA-Gly₄-PLA) size, zeta, and PDI were found to be 110 ± 8.1 nm, 13.7 ± 1.01 mV, 0.19 ± 0.03 and 198 ± 9.01 nm, 8.63 ± 0.21 mV, 0.21 ± 0.08 respectively. The percent encapsulation efficiency (% EE) and percent drug loading (% DL) of BTZ loaded FA-Gly₄-PLA NPs was calculated to be 78.3 ± 4.1 and 12.38 ± 2.1. The Scanning Electron Microscopy (SEM) showed that NPs were slightly biconcave in shape. The in vitro release of BTZ from FA-Gly₄-PLA NPs resulted in the sustained manner. The prepared NPs were less hemolytic than BTZ.

CONCLUSIONS

BTZ loaded Gly₄-PLA NPs apoptotic index was found to be much higher than BTZ but lesser than BTZ loaded FA-Gly₄-PLA against breast cancer cell lines (MDA-MB-231). ROS intracellular assessment assay indicated that BTZ and BTZ loaded FA-Gly₄-PLA NPs exhibited higher ROS production. Conclusively, the BTZ loaded FA-Gly₄-PLA NPs were able to encapsulate more BTZ than BTZ loaded Gly₄-PLA NPs and were found to be more effective as per as in vitro anti-cancer effect is concerned.

Tiny Rare-Earth Fluoride Nanoparticles Activate Tumour Cell Growth via Electrical Polar Interactions

Localised extracellular interactions between nanoparticles and transmembrane signal receptors may well activate cancer cell growth. Herein, tiny LaF₃ and PrF₃ nanoparticles in DMEM+FBS suspensions stimulated tumour cell growth in three different human cell lines (A549, SW837 and MCF7). Size distribution of nanoparticles, activation of AKT and ERK signalling pathways and viability tests pointed to mechanical stimulation of ligand adhesion binding sites of integrins and EGFR via a synergistic action of an ensemble of tiny size nanoparticles (< 10 nm). While tiny size nanoparticles may be well associated with the activation of EGFR, integrin interplay with nanoparticles remains a multifaceted issue. A theoretical motif shows that, within the requisite pN force scale, each ligand adhesion binding site can be activated by a tiny size dielectric nanoparticle via electrical dipole interaction. The size of the active nanoparticle stayed specified by the amount of the surface charges on the ligand adhesion binding site and the nanoparticle, and also by the separating distance between them. The polar component of the electrical dipole force remained inversely proportional to the second power of nanoparticle's size, evincing that only tiny size dielectric nanoparticles might stimulate cancer cell growth via electrical dipole interactions. The work contributes towards recognising different cytoskeletal stressing modes of cancer cells.

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.

The Effect of Absorption-Enhancement and the Mechanism of the PAMAM Dendrimer on Poorly Absorbable Drugs

The polyamidoamine (PAMAM) dendrimer is a highly efficient absorption promoter. In the present study, we studied the absorption-enhancing effects and the mechanism of PAMAM dendrimers with generation 0 to generation 3 (G0–G3) and concentrations (0.1–1.0%) on the pulmonary absorption of macromolecules. The absorption-enhancing mechanisms were elucidated by microarray, western blotting analysis, and PCR. Fluorescein isothiocyanate-labeled dextrans (FDs) with various molecular weights were used as model drugs of poorly absorbable drugs. The absorption-enhancing effects of PAMAM dendrimers on the pulmonary absorption of FDs were in a generation- and concentration-dependent manner. The G3 PAMAM dendrimer with high effectiveness was considered to the best absorption enhancer for improving the pulmonary absorption of FDs. G3 PAMAM dendrimers at three different concentrations were non-toxic to Calu-3 cells. Based on the consideration between efficacy and cost, the 0.1% G3 PAMAM dendrimer was selected for subsequent studies. The results showed that treatment with a 0.1% G3 PAMAM dendrimer could increase the secretion of organic cation transporters (OCTs), OCT1, OCT2, and OCT3, which might be related to the absorption-enhancing mechanisms of the pulmonary absorption of FDs. These findings suggested that PAMAM dendrimers might be potentially safe absorption enhancers for improving absorption of FDs by increasing the secretion of OCT1, OCT2, and OCT3.

Photons Probe Entropic Potential Variation during Molecular Confinement in Nanocavities

In thin polymeric layers, external molecular analytes may well be confined within tiny surface nano/microcavities, or they may be attached to ligand adhesion binding sites via electrical dipole forces. Even though molecular trapping is followed by a variation of the entropic potential, the experimental evidence of entropic energy variation from molecular confinement is scarce because tiny thermodynamic energy density diverseness can be tracked only by sub-nm surface strain. Here, it is shown that water confinement within photon-induced nanocavities in Poly (2-hydroxyethyl methacrylate), (PHEMA) layers could be trailed by an entropic potential variation that competes with a thermodynamic potential from electric dipole attachment of molecular adsorbates in polymeric ligands. The nano/microcavities and the ligands were fabricated on a PHEMA matrix by vacuum ultraviolet laser photons at 157 nm. The entropic energy variation during confinement of water analytes on the photon processed PHEMA layer was monitored via sub-nm surface strain by applying white light reflectance spectroscopy, nanoindentation, contact angle measurements, Atomic Force Microscopy (AFM) imaging, and surface and fractal analysis. The methodology has the potency to identify entropic energy density variations less than 1 pJm⁻³ and to monitor dipole and entropic fields on biosurfaces.

Polyamidoamine Dendrimers for Enhanced Solubility of Small Molecules and Other Desirable Properties for Site Specific Delivery: Insights from Experimental and Computational Studies

Clinical applications of many small molecules are limited due to poor solubility and lack of controlled release besides lack of other desirable properties. Experimental and computational studies have reported on the therapeutic potential of polyamidoamine (PAMAM) dendrimers as solubility enhancers in pre-clinical and clinical settings. Besides formulation strategies, factors such as pH, PAMAM dendrimer generation, PAMAM dendrimer concentration, nature of the PAMAM core, special ligand and surface modifications of PAMAM dendrimer have an influence on drug solubility and other recommendable pharmacological properties. This review, therefore, compiles the recently reported applications of PAMAM dendrimers in pre-clinical and clinical uses as enhancers of solubility and other desirable properties such as sustained and controlled release, bioavailability, bio-distribution, toxicity reduction or enhancement, and targeted delivery of small molecules with emphasis on cancer treatment.

Bendamustine-PAMAM Conjugates for Improved Apoptosis, Efficacy, and in Vivo Pharmacokinetics: A Sustainable Delivery Tactic

Successful delivery of a chemotherapeutic agent like bendamustine still remains a challenge in clinical conditions like chronic lymphatic leukemia (CLL), non-Hodgkin lymphoma (NHL), and multiple myeloma. We have conjugated bendamustine to polyamidoamine (PAMAM) dendrimers after conjugating with N-(hydroxyethyl)maleimide (spacer) via an ester bond. The particle size of PAMAM-bendamustine conjugate was 49.8 ± 2.5 nm. In vitro drug release resulted in sustained release with improved solution stability of drug up to 72 h. In a 24 h cytotoxicity study by MTT assay against human monoblastic leukemia cells (THP-1), the IC50 value for PAMAM-bendamustine was 32.1 ± 4.8 μM compared to 50.42 ± 3.4 μM and 2303 ± 106.5 μM for bendamustine and PAMAM dendrimer, respectively. Significantly higher cell uptake and apoptosis were observed in THP-1 cells by PAMAM-bendamustine conjugate which was confirmed by flow cytometry and confocal laser scanning microscopy. Preliminary in vivo studies undertaken included pharmacokinetics studies, organ distribution studies, and tumor inhibition studies. In healthy Wistar rat model (1CBM IV push model), the pharmacokinetic studies revealed that bioavailability and t_1/2 increased significantly, i.e., almost 8.5-fold (193.8 ± 1.116 vs 22.8 ± 0.158 μg mL^-1/h) and 5.1-fold (0.75 ± 0.005 vs 3.85 ± 0.015 h), respectively, for PAMAM-bendamustine conjugate compared to pure bendamustine ( p < 0.05), however, clearance and volume of distribution were found to be decreased compared to those of free drug. The study suggests that PAMAM-bendamustine conjugate was not only stable for the longer period but also least toxic and highly taken up by THP-1 cells to exert an anticancer effect at the reduced dose. Tumor inhibition and biodistribution studies in tumor-bearing BALB/c mice revealed that PAMAM-bendamustine conjugate was more effective than the pure drug and showed higher accumulation in the tumor.

Metal-containing and related polymers for biomedical applications

A survey of the most recent progress in the biomedical applications of metal-containing polymers is given. Due to the unique optical, electrochemical, and magnetic properties, at least 30 different metal elements, most of them transition metals, are introduced into polymeric frameworks for interactions with biology-relevant substrates via various means. Inspired by the advance of metal-containing small molecular drugs and promoted by the great progress in polymer chemistry, metal-containing polymers have gained momentum during recent decades. According to their different applications, this review summarizes the following biomedical applications: (1) metal-containing polymers as drug delivery vehicles; (2) metal-containing polymeric drugs and biocides, including antimicrobial and antiviral agents, anticancer drugs, photodynamic therapy agents, radiotherapy agents and biocides; (3) metal-containing polymers as biosensors, and (4) metal-containing polymers in bioimaging.

Dendrimer nanoarchitectures for cancer diagnosis and anticancer drug delivery

Dendrimers are novel nanoarchitectures with unique properties including a globular 3D shape, a monodispersed unimicellar nature and a nanometric size range. The availability of multiple peripheral functional groups and tunable surface engineering enable the facile modification of the dendrimer surface with different therapeutic drugs, diagnostic agents and targeting ligands. Drug encapsulation, and solubilizing and passive targeting also equally contribute to the therapeutic use of dendrimers. In this review, we highlight recent advances in the delivery of anticancer drugs using dendrimers, as well as other biomedical and diagnostic applications. Taken together, the immense potential and utility of dendrimers are envisaged to have a significant positive impact on the growing arena of drug delivery and targeting.

Vascular-targeted nanocarriers: design considerations and strategies for successful treatment of atherosclerosis and other vascular diseases

Vascular-targeted nanocarriers are an attractive option for the treatment of a number of cardiovascular diseases, as they allow for more specific delivery and increased efficacy of many small molecule drugs. However, immune clearance, limited cellular uptake, and particle-cell dynamics in blood flow can hinder nanocarrier efficacy in many applications. This review aims to investigate successful strategies for the use of vascular-targeted nanocarriers in the treatment of cardiovascular diseases such as atherosclerosis. In particular, the review will highlight strategies employed for actively targeting the components of the atherosclerotic plaque, including endothelial cells, macrophages, and platelets and passive targeting via endothelial permeability, as well as design specifications (such as size, shape, and density) aimed at enhancing the ability of nanocarriers to reach the vascular wall. WIREs Nanomed Nanobiotechnol 2016, 8:909-926. doi: 10.1002/wnan.1414 For further resources related to this article, please visit the WIREs website.

Nanotechnology in diagnosis and treatment of coronary artery disease

Nanotechnology could provide a new complementary approach to treat coronary artery disease (CAD) which is now one of the biggest killers in the Western world. The course of events, which leads to atherosclerosis and CAD, involves many biological factors and cellular disease processes which may be mitigated by therapeutic methods enhanced by nanotechnology. Nanoparticles can provide a variety of delivery systems for cargoes such as drugs and genes that can address many problems within the arteries. In order to improve the performance of current stents, nanotechnology provides different nanomaterial coatings, in addition to controlled-release nanocarriers, to prevent in-stent restenosis. Nanotechnology can increase the efficiency of drugs, improve local and systematic delivery to atherosclerotic plaques and reduce the inflammatory or angiogenic response after intravascular intervention. Nanocarriers have potential for delivery of imaging and diagnostic agents to precisely targeted destinations. This review paper will cover the current applications and future outlook of nanotechnology, as well as the main diagnostic methods, in the treatment of CAD.