Lysine and citric acid based pegylated polymeric dendritic nano drug delivery carrier and their bioactivity evaluation

The main objective of this work is to synthesize multifunctional nanodendritic structural molecules that can effectively encapsulate hydrophilic as well as hydrophobic therapeutic agents. Four different types of fourth-generation lysine-citric acid based dendrimer have been synthesized in this work: PE-MC-Lys-CA-PEG, TMP-MC-Lys-CA-PEG, PE-MS-Lys-CA-PEG, and TMP-MS-Lys-CA-PEG. The antibacterial drug cefotaxime (CFTX) was further conjugated to these dendrimers. The dendrimer and drug-dendrimer conjugate structures were characterized with the help of FTIR,1H-NMR, and 13C-NMR spectroscopy. Zeta sizer, AFM, and HR-TEM techniques were used to investigate the particle size, surface topography, and structural characteristics of drug-dendrimer conjugates. In vitro drug release was then investigated using dialysis method. Various kinetic drug release models were examined to evaluate the type of kinetic drug release mechanism of the formulations. Cytotoxicity study revealed that the dendrimers encapsulated with CFTX exhibited 2-3% toxicity against healthy epithelial cells, indicating their safe use. Plain dendrimers show 10-15% hemolytic toxicity against red blood cells (RBC), and the toxicity was reduced to 2-3% when CFTX was conjugated to the same dendrimers. The 3rd and 4th generation synthesized drug-dendrimer conjugates exhibit a significantly effective zone of inhibition (ZOI) against both Gram-positive and Gram-negative bacteria. For Gram-positive bacteria, the lower concentration of 0.1 mg/mL showed more than 98% inhibition of drug-dendrimer conjugate samples against B. subtilis and more than 50% inhibition against S. aureus using 0.2 mg/mL, respectively. Moreover, samples with concentrations of 0.5 and 1.0 mg/mL exhibited more than 50% inhibition against S. typhimurium and E. coli, respectively.

Efficient delivery of anticancer drugs using functionalized-Ag-decorated Fe3O4@SiO2 nanocarrier with folic acid and β-cyclodextrin

Nanocarrier surface functionalization has been widely regarded as a promising approach for achieving precise and targeted drug delivery systems. In this work, the fabrication of functionalized-Ag-decorated Fe3O4@SiO2 (Fe3O4@SiO2-Ag) nanocarriers with folic acid (FA) and β-cyclodextrin (BCD) exhibit a remarkable capacity for delivering two types of anticancer drugs, i.e., doxorubicin (DOX) and epirubicin (EPI), into cancer cells. The effective functionalization of Fe3O4@SiO2-Ag nanoparticles has been achieved through the use of cysteine (Cys) as an anchor for attaching FA and BCD via EDC-NHS coupling and Steglich esterification methods, respectively. The findings indicate that surface functionalization had no significant impact on the physicochemical characteristics of the nanoparticles. However, it notably affected DOX and EPI loading and release efficiency. The electrostatic conjugation of DOX/EPI onto the surface of Fe3O4@SiO2-Ag/Cys/FA and Fe3O4@SiO2-Ag/Cys/BCD exhibited maximum loading efficiency of 50-60% at concentration ratio of DOX/EPI to nanoparticles of 1:14. These nanocarriers also achieved an 40-47% DOX/EPI release over 36 days. Furthermore, the drug-loaded functionalized-nanocarrier showed cytotoxic effects on SK-MEL-2 cells, as demonstrated by an in vitro MTT assay. This suggests that the as-prepared functionalized-nanoparticles have promise as a carrier for the efficient anticancer drugs.

Current development of theragnostic nanoparticles for women's cancer treatment

In the biomedical industry, nanoparticles (NPs-exclusively small particles with size ranging from 1-100 nanometres) are recently employed as powerful tools due to their huge potential in sophisticated and enhanced cancer theragnostic (i.e. therapeutics and diagnostics). Cancer is a life-threatening disease caused by carcinogenic agents and mutation in cells, leading to uncontrolled cell growth and harming the body's normal functioning while affecting several factors like low levels of reactive oxygen species, hyperactive antiapoptotic mRNA expression, reduced proapoptotic mRNA expression, damaged DNA repair, and so on. NPs are extensively used in early cancer diagnosis and are functionalized to target receptors overexpressing cancer cells for effective cancer treatment. This review focuses explicitly on how NPs alone and combined with imaging techniques and advanced treatment techniques have been researched against 'women's cancer' such as breast, ovarian, and cervical cancer which are substantially occurring in women. NPs, in combination with numerous imaging techniques (like PET, SPECT, MRI, etc) have been widely explored for cancer imaging and understanding tumor characteristics. Moreover, NPs in combination with various advanced cancer therapeutics (like magnetic hyperthermia, pH responsiveness, photothermal therapy, etc), have been stated to be more targeted and effective therapeutic strategies with negligible side effects. Furthermore, this review will further help to improve treatment outcomes and patient quality of life based on the theragnostic application-based studies of NPs in women's cancer treatment.

Structural Characterization of Cis– and Trans–Pt(NH3)2Cl2 Conjugations with Chitosan Nanoparticles

The conjugation of chitosan 15 and 100 KD with anticancer drugs cis– and trans–Pt (NH₃)₂Cl₂ (abbreviated cis–Pt and trans–Pt) were studied at pH 5–6. Using multiple spectroscopic methods and thermodynamic analysis to characterize the nature of drug–chitosan interactions and the potential application of chitosan nanoparticles in drug delivery. Analysis showed that both hydrophobic and hydrophilic contacts are involved in drug–polymer interactions, while chitosan size and charge play a major role in the stability of drug–polymer complexes. The overall binding constants are K_{ch–15–cis–Pt} = 1.44 (±0.6) × 10⁵ M⁻¹, K_{ch–100–cis–Pt} = 1.89 (±0.9) × 10⁵ M⁻¹ and K_{ch–15–trans–Pt} = 9.84 (±0.5) × 10⁴ M⁻¹, and K_{ch–100–trans–Pt} = 1.15 (±0.6) × 10⁵ M⁻¹. More stable complexes were formed with cis–Pt than with trans–Pt–chitosan adducts, while stronger binding was observed for chitosan 100 in comparison to chitosan 15 KD. This study indicates that polymer chitosan 100 is a stronger drug carrier than chitosan 15 KD in vitro.

Bifunctional folic-conjugated aspartic-modified Fe3O4 nanocarriers for efficient targeted anticancer drug delivery

Functionalization of nanocarriers has been considered the most promising way of ensuring an accurate and targeted drug delivery system. This study reports the synthesis of bifunctional folic-conjugated aspartic-modified Fe3O4 nanocarriers with an excellent ability to deliver doxorubicin (DOX), an anticancer drug, into the intercellular matrix. Here, the presence of amine and carboxylate groups enables aspartic acid (AA) to be used as an efficient anchoring molecule for the conjugation of folic acid (FA) (EDC-NHS coupling) and DOX (electrostatic interaction). Based on the results, surface functionalization showed little effect on the physicochemical properties of the nanoparticles but significantly influenced both the loading and release efficiency of DOX. This is primarily caused by the steric hindrance effect due to large and bulky FA molecules. Furthermore, in vitro MTT assay of B16-F1 cell lines revealed that FA conjugation was responsible for a significant increase in the cytotoxicity of DOX-loaded nanocarriers, which was also found to be proportional to AA concentration. This high cytotoxicity resulted from an efficient cellular uptake induced by the over-expressed folate receptors and fast pH triggered DOX release inside the target cell. Here, the lowest IC50 value of DOX-loaded nanocarriers was achieved at 2.814 ± 0.449 μg mL-1. Besides, further investigation also showed that the drug-loaded nanocarriers exhibited less or no toxicity against normal cells.

Dendrimer as a promising nanocarrier for the delivery of doxorubicin as an anticancer therapeutics

Dendrimers are macromolecules with high-polymeric branching capable of undergoing major modifications. These characteristics make them an efficient nanocarrier capable of encapsulating and delivering drug, antibodies, or any therapeutic gene. The failure of conventional techniques to deliver drug with higher efficacy and reduced side effects has led to the use of nanomedicines including dendrimers. Dendrimers are novel drug carriers that are modified, complexed, and conjugated with different ligands and receptors to target the delivery of drug at the specific site without impacting any of the normal cells in surrounding. Moreover, the biocompatibility and safety of the dendrimers can be altered accordingly by the process of functionalization by PEGylation, acetylation, or amination. Various dendrimers have been designed to incorporate and deliver anticancer drug either in free form or as codelivery in conjugation with other drugs or therapeutic siRNA/DNA. Doxorubicin (DOX) is one such chemotherapeutic drug that acts by disrupting the process of DNA repair in tumor cells and hence is, since long been used for anticancer therapy. Certain adverse effects such as cardiotoxicity has limited the use of conventional DOX and has shifted the focus on use of safe nanodelivery systems viz dendrimers. DOX either in free or salt form can be loaded or encapsulated accordingly within the core of the dendrimers and linked with different receptors expressed over tumor cells to improve targeting in any cancerous organ site. Positive results obtained after cytotoxicity assay and in vivo/in vitro studies on different cancerous cell lines, and grafted models suggested the potential use of multifunctional DOX-dendrimers characterized with controlled release, better penetration, improved bioavailability, and reduced organ toxicity. This review consolidates studies on different types of DOX-loaded dendrimers that were synthesized, investigated, and are currently being explored for better cancer targeting. Foreseeing the prospects of dendrimers and their compatibility with DOX (free/salt), the article was updated with all current insights.

Magnetic tri-bead microrobot assisted near-infrared triggered combined photothermal and chemotherapy of cancer cells

Magnetic micro/nanorobots attracted much attention in biomedical fields because of their precise movement, manipulation, and targeting abilities. However, there is a lack of research on intelligent micro/nanorobots with stimuli-responsive drug delivery mechanisms for cancer therapy. To address this issue, we developed a type of strong covalently bound tri-bead drug delivery microrobots with NIR photothermal response azobenzene molecules attached to their carboxylic surface groups. The tri-bead microrobots are magnetic and showed good cytocompatibility even when their concentration is up to 200 µg/mL. In vitro photothermal experiments demonstrated fast NIR-responsive photothermal property; the microrobots were heated to 50 °C in 4 min, which triggered a significant increase in drug release. Motion control of the microrobots inside a microchannel demonstrated the feasibility of targeted therapy on tumor cells. Finally, experiments with lung cancer cells demonstrated the effectiveness of targeted chemo-photothermal therapy and were validated by cell viability assays. These results indicated that tri-bead microrobots have excellent potential for targeted chemo-photothermal therapy for lung cancer cell treatment.

Chitosan overlaid Fe3O4/rGO nanocomposite for targeted drug delivery, imaging, and biomedical applications

A hybrid and straightforward nanosystem that can be used simultaneously for cancer-targeted fluorescence imaging and targeted drug delivery in vitro was reported in this study. A chitosan (CS) polymer coated with reduced graphene oxide (rGO) and implanted with Fe3O4 nanoparticles was fabricated. The fundamental physicochemical properties were confirmed via FT-IR, XRD, FE-SEM, HR-TEM, XPS, and VSM analysis. The in vivo toxicity study in zebrafish showed that the nanocomposite was not toxic. The in vitro drug loading amount was 0.448 mg/mL-1 for doxorubicin, an anticancer therapeutic, in the rGO/Fe3O4/CS nanocomposite. Furthermore, the pH-regulated release was observed using folic acid. Cellular uptake and multimodal imaging revealed the benefit of the folic acid-conjugated nanocomposite as a drug carrier, which remarkably improves the doxorubicin accumulation inside the cancer cells over-express folate receptors. The rGO/Fe3O4/CS nanocomposite showed enhanced antibiofilm and antioxidant properties compared to other materials. This study's outcomes support the use of the nanocomposite in targeted chemotherapy and the potential applications in the polymer, cosmetic, biomedical, and food industries.

Locating the binding sites of two aminobenzoic acid derivatives on tRNA: drug binding efficacy and RNA structure

The binding of tRNA to aminobenzoic acid derivatives DAB-0 (N'-[4-(2,5-dioxo-pyrrolidin-1-yl)-benzoyl]-hydrazine carboxylic acid tert-butyl ester) and DAB-1 (N'-[4-(2,5-dioxo-2,5-dihydro-pyrrol-1-yl)-benzoyl]-hydrazine carboxylic acid tert-butyl ester) was investigated in aqueous solution at physiological pH. Thermodynamic parameters ΔH⁰ -4.8 to -4.30 (kJ mol^-1), ΔS⁰ 24.20 to 22 (J mol^-1K^-1) and ΔG⁰ -12 to -11.40 (kJ mol^-1) showed that DAB-0 and DAB-1 readily bind tRNA via ionic interactions with DAB-1 forming stronger tRNA adducts. Similar binding sites to A-T and G-C bases were located with DAB-0 and DAB-1. The binding efficacy ranged from 40% to 50%. No alteration of tRNA conformation was detected upon drug complexation. Communicated by Ramaswamy H. Sarma.

Facile synthesis of hollow mesoporous nickel sulfide nanoparticles for highly efficient combinatorial photothermal-chemotherapy of cancer

Traditional techniques for the synthesis of nickel sulfide (NiS) nanoparticles (NPs) always present drawbacks of morphological irregularity, non-porous structure and poor long-term stability, which are extremely unfavorable for establishing effective therapeutic agents. Here, a category of hollow mesoporous NiS (hm-NiS) NPs with uniform spherical structure and good aqueous dispersity were innovatively developed based on a modified solvothermal reaction technique. Upon the successful synthesis of hm-NiS NPs, dopamine was seeded and in situ polymerized into polydopamine (PDA) on the NP surface, followed by functionalization with thiol-polyethylene glycol (SH-PEG) and encapsulation of the chemotherapeutic drug, doxorubicin (DOX), to form hm-NiS@PDA/PEG/DOX (NiPPD) NPs. The resultant NiPPD NPs exhibited a decent photothermal response and stability, attributed to the optical absorption of the hm-NiS nanocore and PDA layer in the near-infrared (NIR) region. Furthermore, stimulus-responsive drug release was achieved under both acidic pH conditions and NIR laser irradiation, owing to the protonation of -NH₂ groups in the DOX molecules and local thermal shock, respectively. Lastly, a strong combinatorial photothermal-chemotherapeutic effect was demonstrated for tumor suppression with minimal systemic toxicity in vivo. Collectively, this state-of-the-art paradigm may provide useful insights to deepen the application of hm-NiS NPs for disease management and precision medicine.

Locating the binding sites of citric acid and gallic acid on milk β-lactoglobulin

β-Lactoglobulin (β-LG) is a member of lipocalin superfamily of transporters for small hydrophobic and hydrophilic molecules. We located the binding sites of citric acid and gallic acid on β-lactoglobulin (β-LG) in aqueous solution at physiological conditions, using spectroscopic methods, thermodynamic analysis and molecular modeling. Thermodynamic parameters ΔH⁰ -9.5 to -6.9 (kJ mol^-1), ΔS⁰ 23.9 to 13.6 (J mol^-1K^-1) and ΔG⁰ -14.5 to -13.6 (kJ mol^-1) showed that acid binds protein via ionic contacts with gallic acid forming stronger protein conjugates consistent with theoretical modeling. Different amino acids are involved in gallic acid and citric acid complexation. Protein conformation was altered with reduction of β-sheet from 58% (free protein) to 46-43% and a major increase in α-helix from 11% (free protein) to 29-23% and random coil structure in the acid-protein, indicating a partial protein destabilization. Communicated by Ramaswamy H. Sarma.

Amino acid-modified PAMAM dendritic nanocarriers as effective chemotherapeutic drug vehicles in cancer treatment: a study using zebrafish as a cancer model

The use of nanomaterials for drug delivery offers many advantages including the targeted delivery of drugs and their controlled release. Nonetheless, entry into the target cells remains a challenge for many nanomaterials used for drug delivery. Moreover, cellular uptake limits the therapeutic efficiency of many anticancer drugs. An important goal is to increase the specific accumulation of these nanoparticles (NPs) at the desired cancerous tissues. Notably, cancer cells show a high demand for some amino acids and we have used this knowledge to develop novel carrier systems. In this study, drug carriers were produced by the conjugation of multiple amino acids such as l-histidine (H) and l-cysteine (C) or single amino acids such as only H with the G4.5 dendrimers (G) to produce GHC aggregates and GH NP carriers, respectively. Doxorubicin was loaded into the G4.5, GH, and GHC dendrimers (G/DOX, GH/DOX and GHC/DOX, respectively) and the release mechanism was demonstrated at pH 7.4 and pH 5.0. GH/DOX and GHC/DOX showed better stability under physiological conditions than the dendrimer alone (G/DOX). GH/DOX and GHC/DOX exhibited higher inhibition of HeLa cell proliferation in in vitro and in vivo studies in zebrafish, confirming the early release of DOX by disrupting the endosomal membrane and triggering the destabilization of carriers at a lower pH of 5.0.

Reasons for enhanced activity of doxorubicin on co-delivery with octa(3-aminopropyl)silsesquioxane

This paper presents results of spectroscopic (NMR, FTIR, fluorescence), Q-TOF mass spectrometry and Z-potential analyses of interactions between octa(3-aminopropyl)silsesquioxane hydrochloride (POSS-NH2·HCl) and anticancer drug - doxorubicin hydrochloride. These studies aimed at explanation of the enhanced activity of doxorubicin on co-delivery with POSS-NH2. The results point to the formation of active complexes via ionic interactions between the ammonium chloride groups of silsesquioxane and the drug, and not, as suggested earlier, via NH⋯N hydrogen bonding. It has also been shown that the main driving force for the formation of the complexes can be strengthened by π-π stacking and hydrogen bonds. The experimental results are supported by quantum mechanical calculations. This work has proven that co-delivery with POSS offers a potentially advantageous and simple approach for improved efficacy in chemotherapy, avoiding often complicated synthesis of conjugates, involving covalent bonding between drug, nanocarrier and targeting agents.

Binding efficacy of aminobenzoic acid derivatives with DNA duplex: drug binding sites and DNA structure and dynamics

Communicated by Ramaswamy H. Sarma.

Application and biomolecular study of functionalized folic acid-dendrimer nanoparticles in drug delivery

We determined the loading efficacy of folic acid - PAMAM - G3 and folic acid - PAMAM - G4 nanoparticles with doxorubicin (Dox), tamoxifen (Tam) and tetracycline (Tet) in aqueous solution at pH 7.2. Thermodynamic parameters ΔH⁰ -16 to -4 (kJ mol^-1), ΔS⁰ 31 to -0.3 (J mol^-1K^-1) and ΔG⁰ -14 to -11 (kJ mol^-1) showed drug folic acid-PAMAM bindings are via ionic, H-bonding and van der Waals interactions. As acid - PAMAM size increased the stability and loading efficacy of drug-polymer conjugates were increased. The order of stability for drug-nanoparticles was doxorubicin > tetracycline > tamoxifen. TEM analysis showed major polymer morphological changes, upon drug encapsulation. Folic acid-PAMAM conjugates are effective drug delivery tools in vitro. Communicated by Ramaswamy H. Sarma.

Biomolecular study and conjugation of two para-aminobenzoic acid derivatives with serum proteins: drug binding efficacy and protein structural analysis

Two aminobenzoic acid derivatives DAB-0 and DAB-1 showed distinct biological properties on murine bladder cancer (BCa) cell line MB49-I. In contrast to DAB-1, DAB-0 does not possess any anti-inflammatory activity and is less toxic. Furthermore, DAB-0 does not interfere with INFγ-induced STAT1 activation and TNFα-induced IκB phosphorylation, while DAB-1 does. In order to rationalize these results, the binding efficacy of DAB-0 and DAB-1 with serum proteins such a human serum albumin (HSA), bovine serum albumin (BSA) and beta-lactoglobulin (β-LG) was investigated in aqueous solution at physiological pH. Multiple spectroscopic methods and thermodynamic analysis were used to determine the binding efficacy of DAB-0 and DAB-1 with serum proteins. Drug-protein conjugation was observed via through ionic contacts. DAB-1 forms stronger adducts than DAB-0, while β-LG shows more affinity with the order of stability β-LG > BSA > HSA. The stronger complexation of DAB-1 with serum proteins might account for its biological potential and transport in the blood. The binding efficacy ranged from 40 to 60%. Major alterations of protein secondary structures were detected upon drug complexation. Serum proteins are capable of delivering DAB-1 in vitro.Communicated by Ramaswamy H. Sarma.

Encapsulation of gadolinium ferrite nanoparticle in generation 4.5 poly(amidoamine) dendrimer for cancer theranostics applications using low frequency alternating magnetic field

Iron oxide-based magnetic resonance imaging (MRI) contrast agents have negative contrast limitations in cancer diagnosis. Gadolinium (Gd)-based contrast agents show toxicity. To overcome these limitations, Gd-doped ferrite (Gd:Fe₃O₄ (GdIO) nanoparticles (NPs) were synthesized as T1-T2 dual-modal contrast agents for MRI-traced drug delivery. A theranostics GdIO encapsulated in a Generation 4.5 PAMAM dendrimer (G4.5-GdIO) was developed by alkaline coprecipitation. The drug-loading efficiency of the NPs was ∼24%. In the presence of a low-frequency alternating magnetic field (LFAMF), a maximum cumulative doxorubicin (DOX) release of ∼77.47% was achieved in a mildly acidic (pH = 5.0) simulated endosomal microenvironment. Relaxometric measurements indicated superior r1 (5.19 mM^-1s^-1) and r2 (26.13 mM^-1s^-1) for G4.5-GdIO relative to commercially available Gd-DTPA. Thus, G4.5-GdIO is promising as an alternative noninvasive MRI-traced cancer drug delivery system.

Complexation of cis-Pt and trans-Pt(NH3)2Cl2 with serum proteins: A potential application for drug delivery

AbbreviationsHAShuman serum albuminBSAbovine serum albuminβ-LGbeta-lactoglobulincis-Pt and trans-PtPt(NH₃)₂Cl₂FTIRFourier transform infraredCommunicated by Ramaswamy H. Sarma.

pH-Labile Magnetic Nanocarriers for Intracellular Drug Delivery to Tumor Cells

We report the development of pH-labile ascorbic acid-coated magnetic nanocarriers (AMNCs) for effective delivery of the anticancer drug doxorubicin hydrochloride (DOX) to tumor cells. The uniqueness of this drug delivery system lies in the covalent conjugation of DOX through carbamate and hydrazone bonds, resulting in a slow and sustained drug release profile at different environmental acidities. X-ray diffraction and transmission electron microscopy analyses reveal the formation of crystalline single-phase Fe₃O₄ nanoparticles with an average size of 10 nm. The changes in the interfacial characteristics of the nanocarriers and the presence of organic coatings are probed by infrared spectroscopy, dynamic light scattering, zeta potential, and thermogravimetric measurements. AMNCs show high colloidal stability in aqueous and cell culture media and possess good magnetic field responsivity and protein resistance characteristics. The drug-loaded nanocarriers exhibited sustained pH-triggered release of drug molecules in acidic mediums, substantial cellular internalization, and significant toxicity toward the proliferation of mouse skin fibrosarcoma (WEHI-164), human breast cancer (MCF-7), and human lung cancer (A549) cells. However, it showed significantly lower toxicity in human normal lung (WI26VA) cells. Overall, these results suggest a pH-sensitive drug release of nanoformulations, which showed selective toxicity to tumor than normal cells.

Polymer-Doxorubicin Prodrug with Biocompatibility, pH Response, and Main Chain Breakability Prepared by Catalyst-Free Click Reaction

Click chemistry has increasing applications of the development of polymer materials and modification of drug carriers. The amino-yne click polymerization reacts quickly at room temperature without catalyst, and the enamine bond (-ena-) gained from the reaction is sensitive to acid and can be used to prepare stimulus-responsive polymeric prodrugs. Herein, we report an alkynyl-terminated polymer containing alternately distributed low molecular weight polyethylene glycol (PEG) and hexamethylenediamino (HMDA) linked by enamine bonds, abbreviated as A-P(PEG-alt-HMDA)-A, which was synthesized within 3 h at 35 °C without catalyst. The polymer was verified to have good water solubility, biocompatibility, and acid-sensitive fracturing. Then, a pH-responsive polymeric prodrug (DOX-ena-PPEG-ena-DOX) was further prepared through the amino-yne click reaction between the alkynyl groups of A-P(PEG-alt-HMDA)-A and the amino group of doxorubicin hydrochloride (DOX·HCl). The resulting prodrug can self-assemble into nanoparticles (NPs) in aqueous solution. The pH responsiveness of the prodrug NPs was demonstrated by a stability experiment of NPs and in vitro drug release behavior measurement. The accumulative release of doxorubicin (DOX) was tested with different pH media, which confirmed that the prodrug NPs could effectively dissociate and release drug under a weak acid microenvironment of lysosome/endosome. Subsequently, we investigated cell cytotoxicity and intracellular uptake of the prodrug. It turned out that the prodrug nanoparticles could be internalized into HeLa cells, release original DOX, and efficiently inhibit the proliferation of cancer cells. These results show that the pH-responsive DOX-ena-PPEG-ena-DOX has the potential for use in cancer therapy.

Off-Stoichiometric Thiol-Ene Chemistry to Dendritic Nanogel Therapeutics

A novel platform of dendritic nanogels is herein presented, capitalizing on the self-assembly of allyl-functional polyesters based on dendritic-linear-dendritic amphiphiles followed by simple cross-linking with complementary monomeric thiols via UV initiated off-stoichiometric thiol-ene chemistry. The facile approach enabled multigram creation of allyl reactive nanogel precursors, in the size range of 190-295 nm, being readily available for further modifications to display a number of core functionalities while maintaining the size distribution and characteristics of the master batch. The nanogels are evaluated as carriers of a spread of chemotherapeutics by customizing the core to accommodate each individual cargo. The resulting nanogels are biocompatible, displaying diffusion controlled release of cargo, maintained therapeutic efficacy, and decreased cargo toxic side effects. Finally, the nanogels are found to successfully deliver pharmaceuticals into a 3D pancreatic spheroids tumor model.

In Vitro and In Vivo Co-delivery of siRNA and Doxorubicin by Folate-PEG-Appended Dendrimer/Glucuronylglucosyl-β-Cyclodextrin Conjugate

We have previously reported the utility of folate-polyethylene glycol-appended dendrimer conjugate with glucuronylglucosyl-β-cyclodextrin (Fol-PEG-GUG-β-CDE) (generation 3) as a tumor-selective carrier for siRNA against polo-like kinase 1 (siPLK1) in vitro. In the present study, we evaluated the potential of Fol-PEG-GUG-β-CDE as a carrier for the low-molecular antitumor drug doxorubicin (DOX). Further, to fabricate advanced antitumor agents, we have prepared a ternary complex of Fol-PEG-GUG-β-CDE/DOX/siPLK1 and evaluated its antitumor activity both in vitro and in vivo. Fol-PEG-GUG-β-CDE released DOX in an acidic pH and enhanced the cellular accumulation and cytotoxic activity of DOX in folate receptor-α (FR-α)-overexpressing KB cells. Importantly, the Fol-PEG-GUG-β-CDE/DOX/siPLK1 ternary complex exhibited higher cytotoxic activity than a binary complex of Fol-PEG-GUG-β-CDE with DOX or siPLK1 in KB cells. In addition, the cytotoxic activity of the ternary complex was reduced by the addition of folic acid, a competitor against FR-α. Furthermore, the ternary complex showed a significant antitumor activity after intravenous administration to the tumor-bearing mice. These results suggest that Fol-PEG-GUG-β-CDE has the potential of a tumor-selective co-delivery carrier for DOX and siPLK1.

Effect of tea catechins on tRNA structure and dynamics

AbbreviationsCcatechinECGepicatechin gallateEGCGEpigallocatechin gallateAAdenineCcytosineGGuanineUuracilFTIRFourier transform infraredCommunicated by Ramaswamy H. Sarma.

Testo and testo-Pt(II) bind DNA at different locations

The development of new targeted anticancer agents able to efficiently and specifically destroy cancer cells with minimal toxic side effects is nowadays a subject of intensive research endeavors. We report the conjugation of testo and testo-Pt(II) (two semi-synthetic testosterone derivatives) with calf thymus DNA in aqueous solution at physiological pH. Multiple spectroscopic methods, thermodynamic analysis and modeling were used to determine the binding efficacy of these drugs to DNA duplex. Thermodynamic parameters showed drug-DNA conjugation occurs via ionic interactions with testo-Pt(II) forming more stable DNA adducts than testo with K_testo-DNA = 1.80 (±0.5) x 10⁵ M^-1 and K_{testo-Pt(II)-DNA} = 2.3 (±0.8) x 10⁵ M^-1. Molecular modeling shows that testo and testo-Pt(II) bind DNA at different locations.

Location of multiple binding sites for testo and testo-Pt(II) with tRNA

We report the binding of testo and testo-Pt(II) complexes (testosterone derivatives) with tRNA in aqueous solution at physiological pH. Thermodynamic parameter ΔH₀ -8 to -3 (kJ mol^-1), ΔS₀ 35 to 18 (J mol^-1K^-1) and ΔG₀ -14 to -13 (kJ mol^-1) and other spectroscopic results showed drug-tRNA binding occurs via ionic contacts with testo-Pt(II) forming more stable tRNA complexes in comparison to testo: K_testo-Pt(II)-tRNA= 3.2 (± 0.9) × 10⁵ M^-1 > K_testo-tRNA= 2.1 (± 0.7) × 10⁵ M^-1. Molecular modeling showed multiple binding sites for testo and testo-Pt(II) on tRNA molecule. Some of the useful molecular descriptors are calculated. Major structural changes were observed for biopolymers upon drug complexation, while tRNA remains in the A-family structures.

Magnetic hyperthermia of breast cancer cells and MRI relaxometry with dendrimer-coated iron-oxide nanoparticles

BACKGROUND

Recently, some studies have focused on dendrimer nanopolymers as a magnetic resonance imaging (MRI) contrast agent or a vehicle for gene and drug delivery. Considering the suitable properties of these materials, they are appropriate candidates for coating iron-oxide nanoparticles which are applied in magnetic hyperthermia. To the best of our knowledge, the novelty of this study is the investigation of fourth-generation dendrimer-coated iron-oxide nanoparticles (G4@IONPs) in magnetic hyperthermia and MRI.

METHODS

IONPs were synthesized via co-precipitation and coated with the fourth generation (G4) of polyamidoamine dendrimer. The cytotoxicity of G4@IONPs with different concentrations was assessed in a human breast cancer cell line (MCF7) and human fibroblast cell line (HDF1). Hemolysis and stability of G4@IONPs were investigated, and in addition, the interaction of these particles with MCF7 cells was assessed by Prussian blue staining. Heat generation and specific absorption rate (SAR) were calculated from measurement and simulation results at 200 and 300 kHz. MCF7 and HDF1 cells were incubated with G4@IONPs for 2 h and then put into the magnetic coil for 120 min. Relaxometry experiments were performed with different concentrations of G4@IONPs with T1- and T2-weighted MR images.

RESULTS

The TEM results showed that G4@IONPs were 10 ± 4 nm. The in vitro toxicity assessments showed that synthesized nanoparticles had low toxicity. The viability of MCF7 cells incubated with G4@IONPs decreased significantly after magnetic hyperthermia. In addition, MR imaging revealed that G4@IONPs improved transverse relaxivity (r2) significantly.

CONCLUSIONS

Our results encouraged the future application of G4@IONPs in magnetic hyperthermia and MR imaging.

Radiation-Sensitive Dendrimer-Based Drug Delivery System

Combination of chemotherapy and radiotherapy is used to enhance local drug delivery while reducing off-target tissue effects. Anticancer drug doxorubicin (DOX) is loaded into l-cysteine modified G4.5 dendrimer (GC/DOX) and released at different pH values in the presence and absence of γ-radiation. Presence of γ-radiation significantly improves DOX release from the GC/DOX under acidic pH conditions, suggesting that GC dendrimer is a radiation-sensitive drug delivery system. GC/DOX is further evaluated by determining cytotoxicity in uterine cervical carcinoma HeLa cells. GC/DOX shows high affinity for cancer cells and effective drug release following an external stimulus (radiation exposure), whereas an in vivo zebrafish study confirms that l-cysteine acts as a radiosensitizer. GC/DOX treatment combined with radiotherapy synergistically and successfully inhibits cancer cell growth.