Polyamidoamine dendrimer-mediated hydrogel for solubility enhancement and anti-cancer drug delivery

The application of hydrogels for anti-cancer drug delivery has garnered considerable interest in the medical field. Current cancer treatment approaches, such as chemotherapy and radiation therapy, often induce severe side effects, causing significant distress and substantial health complications to patients. Hydrogels present an appealing solution as they can be precisely injected into specific sites within the body, facilitating the sustainable release of encapsulated drugs. This localized treatment approach holds great potential for reducing toxicity levels and improving drug delivery efficacy. In this study we developed a hydrogel delivery system containing polyamidoamine (PAMAM) dendrimer and polyethylene glycol (PEG) for solubility enhancement and sustained delivery of hydrophobic anti-cancer drugs. The three selected model drugs, e.g. silibinin, camptothecin, and methotrexate, possess limited aqueous solubility and thus face restricted application. In the presence of vinyl sulfone functionalized PAMAM dendrimer at 45 mg/mL concentration, drug solubility is increased by 37-fold, 4-fold, and 10-fold for silibinin, camptothecin, and methotrexate, respectively. By further crosslinking of the functionalized PAMAM dendrimer and thiolated PEG, we successfully developed a fast-crosslinking hydrogel capable of encapsulating a significant payload of solubilized cancer drugs for sustained release. In water, the drug encapsulated hydrogels release 30%-80% of their loads in 1-4 days. MTT assays of J82 and MCF7 cells with various doses of drug encapsulated hydrogels reveal that cytotoxicity is observed for all three drugs on both J82 and MCF7 cell lines after 48 h. Notably, camptothecin exhibits higher cytotoxicity to both cell lines than silibinin and methotrexate, achieving up to 95% cell death at experimental conditions, despite its lower solubility. Our experiments provide evidence that the PAMAM dendrimer-mediated hydrogel system significantly improves the solubility of hydrophobic drugs and facilitates their sustained release. These findings position the system as a promising platform for controlled delivery of hydrophobic drugs for intratumoral cancer treatment.

Conjugation of Short Oligopeptides to a Second-Generation Polyamidoamine Dendrimer Shows Antibacterial Activity

The growing evolution of bacterial resistance to antibiotics represents a global issue that not only impacts healthcare systems but also political and economic processes. This necessitates the development of novel antibacterial agents. Antimicrobial peptides have shown promise in this regard. Thus, in this study, a new functional polymer was synthesized by joining a short oligopeptide sequence (Phe-Lys-Phe-Leu, FKFL) to the surface of a second-generation polyamidoamine (G2 PAMAM) dendrimer as an antibacterial component. This method of synthesis proved simple and resulted in a high conjugation yield of the product FKFL-G2. To determine its antibacterial potential, FKFL-G2 was subsequently analyzed via mass spectrometry, a cytotoxicity assay, bacterial growth assay, colony-forming unit assay, membrane permeabilization assay, transmission electron microscopy, and biofilm formation assay. FKFL-G2 was found to exhibit low toxicity to noncancerous NIH3T3 cells. Additionally, FKFL-G2 had an antibacterial effect on Escherichia coli and Staphylococcus aureus strains by interacting with and disrupting the bacterial cell membrane. Based on these findings, FKFL-G2 shows promise as a potential antibacterial agent.

Chiral Recognition of Homochiral Poly (amidoamine) Dendrimers Substituted with R- and S-Glycidol by Keratinocyte (HaCaT) and Squamous Carcinoma (SCC-15) Cells In Vitro

The generation 2 and 3 poly(amidoamine) dendrimers (PAMAM G2 and G3) were converted into N-(2,3-dihydroxy)propyl derivatives by the addition of enantiomerically pure S- and R-glycidol. The homochiral dendrimers bind to HaCaT and SCC-15 cell membranes with an R/S glycidol enantioselectivity ratio of 1.5:1, as was quantitatively determined by fluorescence microscopy and visualized by confocal microscopy. Fully substituted G2 and G3 dendrimers were equipped with 32 and 64 N-(2,3-dihydroxy)propyl residues and showed effectively radial symmetry for homochiral derivatives in ¹³C NMR spectrum in contrary to analogs obtained by reaction with rac-glycidol. The sub-stoichiometric derivatives of G2 and G3 were also obtained in order to characterize them spectroscopically. The homochiral dendrimers were labeled with two different fluorescent labels, fluorescein, and rhodamine B, using their isothiocyanates to react with G2 and G3 followed by the addition of S- and R-glycidol. Obtained fluorescent derivatives were deficiently filled with N-(2,3-dihydroxy)propyl substituents due to steric hindrance imposed by the attached label. Nevertheless, these derivatives were used to determine their ability to bind to the cell membrane of human keratinocytes (HaCaT) and squamous carcinoma cells (SCC-15). Confocal microscopy images obtained from cells treated with variously labeled conjugates and fluorescence analysis with fluorescence reader allowed us to conclude that R-glycidol derivatives were bound and entered the cells preferentially, with higher accumulation in cancer cells. The G3 polyamidoamine (PAMAM)-based dendrimers were taken up more efficiently than G2 derivatives. Moreover, S- and R-glycidol furnished dendrimers were highly biocompatible with no toxicity up to 300 µM concentrations, in contrast to the amine-terminated PAMAM analogs.

An Optical Sensor for Dengue Envelope Proteins Using Polyamidoamine Dendrimer Biopolymer-Based Nanocomposite Thin Film: Enhanced Sensitivity, Selectivity, and Recovery Studies

This paper proposes a novel idea to enhance the sensitivity and selectivity of surface plasmon resonance (SPR) optical sensor for detection of dengue virus type-2 envelope proteins (DENV-2 E-proteins) using polyamidoamine (PAMAM) dendrimer biopolymer-based nanocomposite thin film. For this purpose, two ranges of DENV-2 E-protein concentrations, i.e., 0.000008-0.0001 nM and 0.00008-0.005 nM were evaluated, and the lowest detectable concentration was achieved at 0.00008 nM. The incorporation of PAMAM dendrimer-based nanocomposite thin film with an SPR sensor exhibited a significant increase in sensitivity and binding affinity to a lower range DENV-2 E-protein concentrations. Moreover, the proposed sensor displayed good selectivity towards DENV-2 E-proteins and have an average recovery of 80-120%. The findings of this study demonstrated that PAMAM dendrimer-based nanocomposite thin film combined with SPR sensor is a promising diagnostic tool for sensitive and selective detection of DENV-2 E-proteins.

PAMAM G4.5 dendrimers for targeted delivery of ferulic acid and paclitaxel to overcome P-glycoprotein-mediated multidrug resistance

In this study, we prepared ferulic acid (FA) and paclitaxel (PTX) co-loaded polyamidoamine (PAMAM) dendrimers conjugated with arginyl-glycyl-aspartic acid (RGD) to overcome P-glycoprotein (P-gp)-mediated multidrug resistance (MDR). FA was released in greater extent (80%) from the outer layer of the dendrimers compared with PTX (70%) from the interior of the dendrimers. FA improved intracellular availability of PTX via P-gp modulation in drug-resistant cells. In vitro drug uptake data show higher PTX delivery with RGD-PAMAM-FP than with PAMAM-FP in drug resistant KB CH-R 8-5 cell lines. This indicates that RGD facilitates intracellular PTX accumulation through active targeting in multidrug-resistant KB CH-R 8-5 cells. The terminal deoxynucleotidyl transferase 2'-deoxyuridine 5'-triphosphate nick-end labeling assay data and membrane potential analysis in mitochondria confirm the enhanced anticancer potential of RGD-PAMAM-FP nanoaggregates in drug-resistant cells. We also confirmed by the increased protein levels of proapoptotic factors such as caspase 3, caspase 9, p53, and Bax after treatment with RGD-PAMAM-FP nanoaggregates and also downregulates antiapoptotic factors. Hence, FA-PTX co-loaded, RGD-functionalized PAMAM G4.5 dendrimers may be considered as an effective therapeutic strategy to induce apoptosis in P-gp-overexpressing, multidrug-resistant cells.

Mitochondria-Targeted Polyamidoamine Dendrimer-Curcumin Construct for Hepatocellular Cancer Treatment

Mitochondrial malfunction plays a crucial role in cancer development and progression. Cancer cells show a substantially higher mitochondrial activity and greater mitochondrial transmembrane potential than normal cells. This concept can be exploited for targeting cytotoxic drugs to the mitochondria of cancer cells using mitochondrial-targeting compounds. In this study, a polyamidoamine dendrimer-based mitochondrial delivery system was prepared for curcumin using triphenylphosphonium ligands to improve the anticancer efficacy of the drug in vitro and in vivo. For the in vitro evaluations, various methods, such as viability assay, confocal microscopy, flow cytometry, reactive oxygen species (ROS), and real-time polymerase chain reaction analyses, were applied. Our findings showed that the targeted-dendrimeric curcumin (TDC) could successfully deliver and colocalize the drug to the mitochondria of the cancer cells, and selectively induce a potent apoptosis and cell cycle arrest at G2/M. Moreover, at a low curcumin dose of less than 25 μM, TDC significantly reduced adenosine triphosphate and glutathione, and increased the ROS level of the isolated rat hepatocyte mitochondria. The in vivo studies on the Hepa1-6 tumor-bearing mice also indicated a significant tumor suppression effect and the highest median survival days (Kaplan-Meier survival estimation and log-rank test) after treatment with the TDC construct compared to the free curcumin and untargeted construct. Besides its targeted nature and safety, the expected improved solubility and stability represent the prepared targeted-dendrimeric construct as an up-and-coming candidate for cancer treatment. The results of this study emphasize the promising route of mitochondrial targeting as a practical approach for cancer therapy, which can be achieved by optimizing the delivery method.

Novel Ce(III)-Metal Organic Framework with a Luminescent Property To Fabricate an Electrochemiluminescence Immunosensor

We designed a novel luminescent metal-organic framework (MOF) named Ce-TCPP-LMOF (CTM) through a simple one-pot solvothermal method. CTM was synthesized by using the emerging electrochemiluminescent (ECL) material (4,4',4″,4‴-(porphine-5,10,15,20-tetrayl)tetrakis(benzoic acid) as the organic ligand and Ce(III) as the metal node. We found that CTM not only has the remarkable ability to emit light but also has a uniform "sandwich biscuit" shape and suitable nanoscale size, which are promising for further applications. We also applied CTM to construct a novel ECL immunosensor and achieve sensitive detection of the proprotein convertase subtilisin/kexin type 9 (PCSK9), a biomarker related to cardiovascular diseases. To further amplify the ECL signal of CTM, a novel dual-amplified signal strategy was established by inducing a polyamidoamine dendrimer (PAMAM) and gold nanoparticles (AuNPs). Importantly, we first proved that the ECL signal of the CTM/S₂O₈^2- system could be enhanced by the PAMAM electric field. As the electron transfer rate was accelerated by the AuNP layer, this ECL signal was further enhanced in AuNP-modified electrodes. The ECL immunosensor showed desirable performance for PCSK9 analysis within a detection range of 50 fg mL^-1 to 10 ng mL^-1 and a low limit of detection of 19.12 ± 2.69 fg mL^-1. Real sample detection suggested that the immunosensor holds great potential for analyzing clinical serum samples.

Dendrimer mediated targeting of siRNA against polo-like kinase for the treatment of triple negative breast cancer

Irresponsiveness of triple negative breast cancer (TNBC) toward conventional therapies has drawn attention toward siRNA therapeutics. In gene delivery, dendrimers are gaining significant attention due to their characteristic features and polo-like kinase (PLK1) is reported as a potential target for TNBC. In this work, phosphorus and polyamidoamine dendrimer (generation 3 and 4 of each type) are explored to address delivery challenges of PLK1 siRNA (siPLK1). Dendriplexes were formed and complexation was found at 3:1 N/P ratio for all dendrimers by gel electrophoresis. Complexation was also supported by zeta potential, circular dichroism and intercalation assay. Dendriplexes were found to be stable in presence of ribonuclease and serum. Dendriplexes resulted in enhanced cell uptake of siPLK1 compared to siPLK1 solution in MDA-MB-231 and MCF-7 cells. Dendriplexes caused increased cell arrest in sub-G1 phase compared to solution. These observations suggested phosphorus and polyamidoamine dendrimers as potential carriers for siPLK1 delivery to treat TNBC.

A Polyamidoamine Dendrimer-Based Electrochemical Immunosensor for Label-Free Determination of Epithelial Cell Adhesion Molecule- Expressing Cancer Cells

A new electrochemical immunosensor for cancer cell detection based on a specific interaction between the metastasis-related antigen of epithelial cell adhesion molecule (EpCAM) on the cell membrane and its monoclonal antibody (Anti-EpCAM) immobilized on a gold electrode has been developed. The amino-terminated polyamidoamine dendrimer (G6 PAMAM) was first covalently attached to the 3-mercaptopropionic acid (MPA)-functionalized gold electrode to obtain a thin film, and then completely carboxylated by succinic anhydride (SA). Next, the Anti-EpCAM was covalently bound with the G6 PAMAM to obtain a stable recognition layer. In the presence of the EpCAM expressing hepatocellular carcinomas cell line of HepG2, the specific immune recognition (Anti-EpCAM/EpCAM) led to an obvious change of the electron transfer ability. The properties of the layer-by-layer assembly process was examined by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The final determination of HepG2 cells was performed in the presence of the reversible [Fe(CN)₆]^3−/4− redox couple using impedance technique. Based on the advantages of PAMAM nanomaterial and immune reaction, a linear response to HepG2 cells ranging from 1 × 10⁴ to 1 × 10⁶ cells mL⁻¹ with a calculated detection limit of 2.1 × 10³ cells mL⁻¹ was obtained. We expect this method can provide a potential tool for cancer cell monitoring and protein expression analysis.

Antiproliferative effect of double suicide gene delivery mediated by polyamidoamine dendrimers in human Tenon's capsule fibroblasts

The aim of the present study was to investigate the therapeutic potential of a double suicide gene, thymidine kinase (TK) combined with cytosine deaminase (CD), mediated by generation of 5-polyamidoamine dendrimers (G5-PAMAM-D) on human Tenon's capsule fibroblasts (HTFs) as an anti-scarring agent. The pAcGFP1-Hyg-TK-CD plasmid was transfected into HTFs, and reverse-transcription polymerase chain reaction (RT-PCR) was used to detect TK-CD expression. MTT cell proliferation assay was used to evaluate the cytotoxic effects of ganciclovir (GCV) and 5-flurocytosine (5-FC) on HTFs. The optimal concentration of GCV and 5-FC in TK-CD transfected HTFs (HTF-TK-CD) was selected by accessing the lowest and highest cytotoxicity caused, respectively. The morphological changes of transfected HTFs following treatment with GCV and 5-FC were observed by light and transmission electron microscopy. Results demonstrated that the double suicide gene TK-CD mediated by the G5-PAMAM-D delivery system was successfully expressed in HTFs as determined by RT-PCR. A concentration of 3 µg/ml GCV and 200 µg/ml 5-FC was identified as optimal for these prodrugs. The growth rate and number of HTF-TK-CD cells decreased following treatment with GCV and 5-FC as revealed by light microscopy. Additionally, the prodrugs GCV and 5-FC not only demonstrated toxicity on transfected HTFs but also exerted a 'bystander effect'. The present study illustrated that the double suicide gene TK-CD delivery mediated by G5-PAMAM-D was effective in reducing HTF proliferation and inducing cell apoptosis. Furthermore, TK-CD delivery mediated by G5-PAMAM-D may be used as an anti-scarring agent and provide a therapeutic potential for patients requiring glaucoma filtration surgery.

Apoptin Gene Delivery by the Functionalized Polyamidoamine (PAMAM) Dendrimer Modified with Ornithine Induces Cell Death of HepG2 Cells

The use of tumor-specific therapeutic agents is a promising option for efficient and safe nonviral gene transfer in gene therapy. In this study, we describe the efficacy of polyamidoamine (PAMAM)-based nonviral gene delivery carriers, namely, an ornithine conjugated PAMAM (PAMAM-O) dendrimer in delivering apoptin, a tumor-specific killer gene, into human hepatocellular carcinoma (HepG2 cells) and dermal fibroblasts. We analyzed the transfection efficiency by the luciferase assay and assessed cell viability in both cell types. The transfection efficiency of the PAMAM-O dendrimer was found to be higher than that of the PAMAM dendrimer. Moreover, the cytotoxicity of the PAMAM-O dendrimer was very low. We treated both cell types with a polyplex of PAMAM-O dendrimer with apoptin, and analyzed its cellular uptake and localization by confocal microscopy. Cell cycle distribution, tetramethylrhodamine, ethyl ester (TMRE) analysis, and transmission electron microscopy imaging showed that apoptin induced cell death in HepG2 cells. We therefore demonstrated that a PAMAM-O/apoptin polyplex can be used as an effective therapeutic strategy in cancer owing to its effectiveness as a suitable nonviral gene vector for gene therapy.

A Supramolecular Approach toward Bioinspired PAMAM-Dendronized Fusion Toxins

Nature has provided a highly optimized toolbox in bacterial endotoxins with precise functions dictated by their clear structural division. Inspired by this streamlined design, a supramolecular approach capitalizing on the strong biomolecular (streptavidin (SA))-biotin interactions is reported herein to prepare two multipartite fusion constructs, which involves the generation 2.0 (D2) or generation 3.0 (D3) polyamidoamine-dendronized transporter proteins (dendronized streptavidin (D3SA) and dendronized human serum albumin (D2HSA)) non-covalently fused to the C3bot1 enzyme from Clostridium botulinum, a potent and specific Rho-inhibitor. The fusion constructs, D3SA-C3 and D2HSA-C3, represent the first examples of dendronized protein transporters that are fused to the C3 enzyme, and it is successfully demonstrated that the C3 Rho-inhibitor is delivered into the cytosol of mammalian cells as determined from the characteristic C3-mediated changes in cell morphology and confocal microscopy. The design circumvents the low uptake of the C3 enzyme by eukaryotic cells and holds great promise for reprogramming the properties of toxin enzymes using a supramolecular approach to broaden their therapeutic applications.

Manno-oligosaccharide-binding ability of mouse RegIV/GST-fusion protein evaluated by complex formation with the carbohydrate-containing polyamidoamine dendrimer

The carbohydrate-binding properties of the C-type lectin-like mouse RegIV and glutathione S-transferase-fusion protein (GST-mRegIV) were examined using carbohydrate-containing polyamidoamine dendrimers (PD). GST-mRegIV showed affinity for mannan- and manno-oligosaccharide containing PD. Binding was inhibited by manno-oligosaccharides but not by mannose or other tested carbohydrates, suggesting that the binding site may have an extended structure in contrast with typical C-type lectins.

Combination of running-buffer-mediated extraction and polyamidoamine-dendrimer-assisted capillary electrophoresis for rapid and sensitive determination of free fatty acids in edible oils

A method was developed for determining free fatty acids in edible plant oils by incorporation of running-buffer-mediated liquid-liquid extraction and polyamidoamine-dendrimer-assisted capillary electrophoresis-capacitively coupled contactless conductivity detection. The recoveries for the extraction were in the range of 90.1% and 110.3%. Addition of dendrimer to the running buffer improved the separation of fatty acids. Under the optimized buffer conditions, i.e., 3 mM pelargonic acid, 39 mM tris(hydroxymethyl)aminomethane, 30 mM polyoxyethylene 23 lauryl ether, 35% acetonitrile, 15% 2-propanol, 2.5% 1-octanol, and 300 μM polyamidoamine generation 2 at apparent pH 8.53, the 10 model fatty acids were separated in 18 min with detection limits ranging from 0.46 to 3.28 μM. The successful determination of fatty acids in real samples suggests that the method is simple, cost-effective, and easy to operate and is suitable for scanning free fatty acid in edible plant oils.

Toxicity of PAMAM-coated gold nanoparticles in different unicellular models

Polyamidoamine (PAMAM) dendrimers are used for many pharmaceutical and biomedical applications. However, the toxicological risks of several PAMAM-based compounds are still not fully evaluated, despite evidences of PAMAM deleterious effects on biological membranes, leading to toxicity. In this report, we investigated the toxicity of generation 0 PAMAM-coated gold nanoparticles (AuG0 NPs) in four different models to determine how different cellular systems are affected by PAMAM-coated NPs. Toxicity was evaluated in two mammalian cell lines, Neuro 2A and Vero, in the green alga Chlamydomonas reinhardtii and the bacteria Vibrio fischeri. AuG0 NP treatments reduced cell metabolic activity in algal and bacterial cells, measured by esterase enzymatic activity (C. reinhardtii) and luminescence emission (V. fischeri). EC50 value after 30 min of treatment was similar in both organisms, with 0.114 and 0.167 mg mL(-1) for C. reinhardtii and V. fischeri, respectively. On the other hand, AuG0 NPs induced no change of mitochondrial activity in mammalian cells after 24 h of treatment to up to 0.4 mg mL(-1) AuG0 NPs. Change in the absorption spectra of AuG0 NP in the mammalian cell culture media may indicate an alteration of NP properties that contributed to the low toxicity of AuG0 NPs in mammalian cells. For a safe development of PAMAM-based nanomaterials, the difference of sensitivity between mammalian and microbial cells, as well as the modulation of NPs toxicity by medium properties, should be taken into account when designing PAMAM NPs for applications that may lead to their introduction in the environment.

Re-evaluation of the involvement of NK cells and C-type lectin-like NK receptors in modulation of immune responses by multivalent GlcNAc-terminated oligosaccharides

Recognition of glycosylation patterns is one of the basic features of innate immunity. Ability of C-type lectin-like receptors such as NKR-P1 to bind saccharide moieties has become recently a controversial issue. In the present study, binding assay with soluble fluorescently labeled recombinant rat NKR-P1A and mouse NKR-P1C proteins revealed apparently no affinity to the various neoglycoproteins. Lack of functional linkage between NKR-P1 and previously described saccharide binder was supported by the fact, that synthetic N-acetyl-D-glucosamine octabranched dendrimer on polyamidoamine scaffold (GN8P) did not change gene expression of NKR-P1 isoforms in C57BL/6 and BALB/c mice divergent in the NK gene complex (both in vitro and in vivo). Surprisingly, N-acetyl-D-glucosamine-coated tetrabranched polyamido-amine dendrimer specifically binds to NKT cells and macrophages but not to NK cells (consistently with changes in cytokine patterns). Despite the fact that GN8P has been tested as an immunomodulator in anti-cancer treatment animal models for many years, surprisingly no changes in cytokine profiles in serum relevant to anti-cancer responses using B16F10 and CT26 harboring mouse strains C57BL/6 and BALB/c are observed. Our results indicate possible indirect involvement of NK cells in GN8P mediated immune responses.

Novel peptide-dendrimer conjugates as drug carriers for targeting nonsmall cell lung cancer

Phage display technology has been demonstrated to be a powerful tool for screening useful ligands that are capable of specifically binding to biomarkers on the surface of tumor cells. The ligands found by this technique, such as peptides, have been successfully applied in the fields of early cancer diagnostics and chemotherapy. In this study, a novel nonsmall cell lung cancer-targeting peptide (LCTP, sequence RCPLSHSLICY) was screened in vivo using a Ph.D.-C7C(™) phage display library. In order to develop a universal tumor-targeting drug carrier, the LCTP and fluorescence-labeled molecule (FITC) were conjugated to an acetylated polyamidoamine (PAMAM) dendrimer of generation 4 (G4) to form a PAMAM-Ac-FITC-LCTP conjugate. The performance of the conjugate was first tested in vitro. In vitro results of cell experiments analyzed by flow cytometry and inverted fluorescence microscopy indicated that PAMAM-Ac-FITC-LCTP was enriched more in NCI-H460 cells than in 293T cells, and cellular uptake was both time- and dose-dependent. The tissue distribution of the conjugate in athymic mice with lung cancer xenografts was also investigated to test the targeting efficiency of PAMAM-Ac-FITC-LCTP in vivo. The results showed that LCTP can effectively facilitate the targeting of PAMAM-Ac-FITC-LCTP to nonsmall cell lung cancer cells and tumors. These results suggest that the LCTP-conjugated PAMAM dendrimer might be a promising drug carrier for targeted cancer diagnosis and treatment.