Targeted pH-responsive delivery of rosmarinic acid via phenylboronic acid functionalized mesoporous silica nanoparticles for liver and lung cancer therapy

Currently, chemotherapy is one of the most practiced approaches for the treatment of cancers. However, existing chemotherapeutic drugs have poor aqueous solubility, poor selectivity, higher systematic toxicity, and poor target accumulation. In this study, we designed and synthesized a boronic acid/ester-based pH-responsive nano-valve that specifically targets the microenvironment in cancer cells. The nano-valve comprises phenylboronic acid-coated mesoporous silica nanoparticles (B-MSN) loaded with polyphenolic compound Rosmarinic acid (ROS-B-MSN). The nano-valve was further coated with lignin (LIG) to achieve our desired LIG-ROS-BMSN nano-valve for targeted chemotherapy against Hep-G2 and NCI-H460 cell lines. The structure and properties of NPs were characterized by Fourier-transformed infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM) in combination with EDX, and Dynamic light scattering (DLS). The outcomes revealed that the designed LIG-ROS-BMSN were in the nanorange (144.1 ± 0.70 nm), had negative Zeta potential (-15.7 ± 0.46 mV) and had a nearly spherical morphology. In vitro, drug release investigations showed a controlled pH-dependent release profile under mild acidic conditions that could enhance the targeted chemotherapeutic response against cancer in mild acidic environments. The obtained LIG-ROS-BMSN nano valve achieved significantly lower IC50 values of (1.70 ± 0.01 μg/mL and 3.25 ± 0.14 μg/mL) against Hep-G2 and NCI-H460 cell lines as compared to ROS alone, which was (14.0 ± 0.7 μg/mL and 29.10 ± 0.25 μg/mL), respectively. The cellular morphology before and after treatment was further confirmed via inverted microscopy. The outcomes of the current study imply that our designed LIG-ROS-BMSN nanovalve is a potential carrier for cancer chemotherapeutics.

Hyaluronic acid functionalized citric acid dendrimer/UiO-66-COOH as a stable and biocompatible platform for daunorubicin delivery

This work aimed to prepare a new system for daunorubicin (DNR) delivery to improve therapeutic efficiency and decrease unwanted side effects. Typically, at first, a carboxylic acid functional group containing metal-organic framework (UiO-66-COOH) was synthesized in a simple way. Then, a third generation of citric acid dendrimer (CAD G3) was grown on it (UiO-66-COOH-CAD G3). Finally, the system was functionalized with pre-modified hyaluronic acid (UiO-66-COOH-CAD-HA). SEM analysis displayed that the synthesized particles have a spherical shape with an average particle size ranging from 260 to 280 nm. An increase in hydrodynamic diameter from 223 nm for UiO-66-COOH to 481 nm for UiO-66-COOH-CAD-HA is a sign of success in the performed reactions. Also, the average pore size was calculated at about 4.04 nm. The DNR loading efficiency of UiO-66-COOH-CAD-HA was evaluated at ∼74 % (DNR@UiO-66-COOH-CAD-HA). It was observed that the drug release rate at a lower pH is more than higher pH. The maximum hemolysis of <3 % means that the UiO-66-COOH-CAD-HA is hemocompatible. The use of DNR-loaded UiO-66-COOH-CAD-HA led to cell-killing of 77.9 % for MDA-MB 231. These results specified the great potential of UiO-66-COOH-CAD-HA for tumor drug delivery, so it could be proposed as a new carrier for anticancer agents to minimize adverse effects and improve therapeutic efficacy.

Chitosan-Biotin-Conjugated pH-Responsive Ru(II) Glucose Nanogel: A Dual Pathway of Targeting Cancer Cells and Self-Drug Delivery

The current study paves the way for improved chemotherapy by creating pH-responsive nanogels (NGs) (GC1 and GC2) loaded with synthetic ruthenium(II) arene complexes to increase biological potency. NGs are fabricated by the conjugation of chitosan (CTS)-biotin biopolymers that selectively target the cancer cells as CTS has the pH-responsive property, which helps in releasing the drug in cancer cells having pH ∼ 5.5, and biotin provides the way to target the cancer cells selectively due to the overexpression of integrin. The synthesized compounds and NGs were thoroughly characterized using various spectroscopic and analytical techniques such as NMR, electrospray ionization-mass spectrometry, Fourier transform infrared, UV-vis, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, rheology, Brunauer-Emmett-Teller, and others. NGs displayed exceptional increased efficacy toward cancerous cells with IC50 values ranging from 7.50 to 18.86 μM via induced apoptosis in three human cancer cell lines. Apart from its potency, NGs were found to be highly selective toward cancer cells. Moreover, based on the results of immunoblot analysis, it was observed that the synthesized compounds exhibit a significant increase in the expression of cleaved caspase-3 and a decrease in the expression of the antiapoptotic protein BCL-XL. Interestingly, the complexes were discovered to have the additional capability of catalyzing the conversion of NADH to NAD+, leading to the generation of radical oxygen species within the cells. Additionally, it was discovered that NG-induced apoptosis depends on ROS production and DNA binding. A narrower range of LD50 values (1185.93 and 823.03 μM) was seen after administering NGs to zebrafish embryos in vivo. The results support the use of drug-loaded NGs as potential chemotherapeutic and chemopreventive agents for human cancer cells.

New Polyvinyl Alcohol/Succinoglycan-Based Hydrogels for pH-Responsive Drug Delivery

We fabricated new hydrogels using polyvinyl alcohol (PVA) and succinoglycan (SG) directly isolated and obtained from Sinorhizobium meliloti Rm 1021 via the freeze-thaw method. Both the composition of the hydrogels and the freeze-thaw cycles were optimized to maximize the swelling ratio for the preparation of the PVA/SG hydrogels. During the optimization process, the morphology and conformational change in the hydrogel were analyzed by scanning electron microscopy, rheological measurements, and compressive tests. An optimized hydrogel with a maximum swelling ratio of 17.28 g/g was obtained when the composition of PVA to SG was 50:50 (PVA/SG 50/50) and the total number of freeze-thaw cycles was five. The PVA/SG 50/50 hydrogel had the largest pore with 51.24% porosity and the highest cross-over point (28.17%) between the storage modulus (G') and the loss modulus (G″). The PVA/SG 50/50 hydrogel showed improved thermal stability owing to its interaction with thermally stable SG chains. The improvement in the thermal stability was confirmed by thermogravimetric analysis and differential scanning calorimetry. In addition, the PVA/SG 50/50 hydrogel showed differential drug release according to the corresponding pH under acidic conditions of pH 1.2 and slightly basic conditions of pH 7.4. Furthermore, the cell viability test on the HEK-293 cell line for that hydrogel demonstrated that the PVA/SG 50/50 hydrogel was non-toxic and biocompatible. Therefore, this hydrogel could be a potential scaffold capable of pH-responsive drug delivery for chronic wound dressing applications.

Internally bridged nanosilica for loadings and release of sparsely soluble compounds

The engineering of a new monodisperse colloid with a sea urchin-like structure with a large complex internal structure is reported, in which silica surfaces are bridged by an aromatic organic cross-linker to serve as a nanocarrier host for drugs such as doxorubicin (DOX) against breast cancer cells. While dendritic fibrous nanosilica (DFNS) was employed and we do not observe a dendritic structure, these particles are referred to as sea urchin-like nanostructured silica (SNS). Since the structure of SNS consists of many silica fibrils protruding from the core, similar to the hairs of a sea urchin. For the aromatic structured cross-linker, bis(propyliminomethyl)benzene (b(PIM)B-S or silanated terephtaldehyde) were employed, which are prepared with terephtaldehyde and 3-aminopropyltriethoxy-silane (APTES) through a simple Schiff base reaction. b(PIM)B-S bridges were introduced into SNS under open vessel reflux conditions. SPS refers to the product obtained by incorporating the cross-linker b(PIM)B-S in ultra-small colloidal SNS particles. In-situ incorporation of DOX molecules resulted in SPS-DOX. The pH-responsive SPS nanocomposites were tested as biocompatible nanocarriers for controllable doxorubicin (DOX) delivery. We conclude that SPS is a unique colloid which has promising potential for technological applications such as advanced drug delivery systems, wastewater remediation and as a catalyst for green organic reactions in water.

Hydrophobic Modification of Poly(γ-glutamic acid) by Grafting 4-Phenyl-butyl Side Groups for the Encapsulation and Release of Doxorubicin

The delivery of drugs is a great challenge, since most of active pharmaceutical ingredients developed today are hydrophobic and poorly water soluble. From this perspective, drug encapsulation on biodegradable and biocompatible polymers can surpass this problem. Poly(γ-glutamic acid) (PGGA), a bioedible and biocompatible polymer has been chosen for this purpose. Carboxylic side groups of PGGA have been partially esterified with 4-phenyl-butyl bromide, producing a series of aliphatic-aromatic ester derivatives with different hydrophilic-lipophilic balances. Using nanoprecipitation or emulsion/evaporation methods, these copolymers were self-assembled in a water solution, forming nanoparticles with average diameters between 89 and 374 nm and zeta potential values between -13.1 and -49.5 mV. The hydrophobic core containing 4-phenyl-butyl side groups was used for the encapsulation of an anticancer drug, such as Doxorubicin (DOX). The highest encapsulation efficiency was reached for a copolymer derived from PGGA, with a 46 mol% degree of esterification. Drug release studies carried out for 5 days at different pHs (4.2 and 7.4) indicated that DOX was released faster at pH 4.2, revealing the potential of these nanoparticles as chemotherapy agents.

Enteric Polymer-Coated Porous Silicon Nanoparticles for Site-Specific Oral Delivery of IgA Antibody

Porous silicon (pSi) nanoparticles are loaded with Immunoglobulin A-2 (IgA2) antibodies, and the assembly is coated with pH-responsive polymers on the basis of the Eudragit family of enteric polymers (L100, S100, and L30-D55). The temporal release of the protein from the nanocomposite formulations is quantified following an in vitro protocol simulating oral delivery: incubation in simulated gastric fluid (SGF; at pH 1.2) for 2 h, followed by a fasting state simulated intestinal fluid (FasSIF; at pH 6.8) or phosphate buffer solution (PBS; at pH 7.4). The nanocomposite formulations display a negligible release in SGF, while more than 50% of the loaded IgA2 is released in solutions at a pH of 6.8 (FasSIF) or 7.4 (PBS). Between 21 and 44% of the released IgA2 retains its functional activity. A capsule-based system is also evaluated, where the IgA2-loaded particles are packed into a gelatin capsule and the capsule is coated with either EudragitL100 or EudragitS100 polymer for a targeted release in the small intestine or the colon, respectively. The capsule-based formulations outperform polymer-coated nanoparticles in vitro, preserving 45-54% of the activity of the released protein.

Cancer-Targeted Chitosan-Biotin-Conjugated Mesoporous Silica Nanoparticles as Carriers of Zinc Complexes to Achieve Enhanced Chemotherapy In Vitro and In Vivo

Despite being the most common component of numerous metalloenzymes in the human body, zinc complexes are still under-rated as chemotherapeutic agents. Herein, the present study opens up a key route toward enhanced chemotherapy with the help of two Zn^II complexes (ZnMBC) synthesized alongside Mannich base ligands to upsurge biological potency. Further, well-established mesoporous silica nanoparticles (MSNs) have been chosen as carriers of the titled metallodrugs in order to achieve anticancer drug delivery. A pH-sensitive additive, namely, chitosan (CTS) conjugated with biotin is tagged to MSNs for the targeted release of core agents inside tumors selectively. In general, CTS blocks ZnMBC inside the mesopores of MSNs, and biotin acts as a targeting ligand to improve tumor-specific cellular uptake. CTS-biotin surface decoration significantly enhanced the cellular uptake of ZnMBC through endocytosis. A panel of four human cancer cell lines has revealed that ZnMBC (1/2)@MSNs-CTS-biotin nanoparticles (NPs) exhibits unprecedented enhanced cytotoxicity toward cancer cells with IC₅₀ values ranging from 6.5 to 28.8 μM through induction of apoptosis. NPs also possess great selectivity between normal and cancer cells despite this potency. Two-photon-excited in vitro imaging of normal (HEK) and cancer (HeLa) cells has been performed to confirm the biased drug delivery. Also, NP-induced apoptosis was found to be dependent on targeting DNA and ROS generation. Moreover, a lower range of LD₅₀ values (153.6-335.5 μM) were observed upon treatment zebrafish embryos with NPs in vivo. Because of the anatomical similarity to the human heart, the heart rate of NP-treated zebrafish has been analyzed in assessing the cardiac functions, which is in favor of the early clinical trials of ZnMBC (1/2)@MSNs-CTS-biotin candidates for their further evaluation as a chemotherapeutic and chemopreventive agent toward human cancers, especially adenocarcinoma.

Zwitterionic Block Copolymer Prodrug Micelles for pH Responsive Drug Delivery and Hypoxia-Specific Chemotherapy

Tirapazamine (TPZ) and its derivatives (TPZD) have shown their great potential for efficiently killing hypoxic cancer cells. However, unsatisfactory clinical outcomes resulting from the low bioavailability of the low-molecular TPZ and TPZD limited their further applications. Precise delivery and release of these prodrugs via functional nanocarriers can significantly improve the therapeutic effects due to the targeted drug delivery and enhanced permeability and retention (EPR) effect. Herein, zwitterionic block copolymer (BCP) micelles with aldehyde functional groups are prepared from the self-assembly of poly(2-methacryloyloxyethyl phosphorylcholine-b-poly(di(ethylene glycol) methyl ether methacrylate-co-4-formylphenyl methacrylate) [PMPC-b-P(DEGMA-co-FPMA)]. TPZD is then grafted onto PMPC-b-P(DEGMA-co-FPMA) to obtain a polymer-drug conjugate, PMPC-b-P(DEGMA-co-FPMA-g-TPZD) (BCP-TPZ), through the formation of a pH-responsive imine bond, exhibiting a pH-dependent drug release profile owing to the cleavage of the imine bond under acidic conditions. Outstandingly, BCP-TPZ shows around 13.7-fold higher cytotoxicity to hypoxic cancer cells in comparison to normoxic cancer cells evaluated through an in vitro cytotoxicity assay. The pH-responsiveness and hypoxia-specific cytotoxicity confer BCP-TPZ micelles a great potential to achieve precise delivery of TPZD and thus enhance the therapeutic effect toward tumor-hypoxia.

pH-Responsive Release of Ruthenium Metallotherapeutics from Mesoporous Silica-Based Nanocarriers

Ruthenium complexes are attracting interest in cancer treatment due to their potent cytotoxic activity. However, as their high toxicity may also affect healthy tissues, efficient and selective drug delivery systems to tumour tissues are needed. Our study focuses on the construction of such drug delivery systems for the delivery of cytotoxic Ru(II) complexes upon exposure to a weakly acidic environment of tumours. As nanocarriers, mesoporous silica nanoparticles (MSN) are utilized, whose surface is functionalized with two types of ligands, (2-thienylmethyl)hydrazine hydrochloride (H1) and (5,6-dimethylthieno[2,3-d]pyrimidin-4-yl)hydrazine (H2), which were attached to MSN through a pH-responsive hydrazone linkage. Further coordination to ruthenium(II) center yielded two types of nanomaterials MSN-H1[Ru] and MSN-H2[Ru]. Spectrophotometric measurements of the drug release kinetics at different pH (5.0, 6.0 and 7.4) confirm the enhanced release of Ru(II) complexes at lower pH values, which is further supported by inductively coupled plasma optical emission spectrometry (ICP-OES) measurements. Furthermore, the cytotoxicity effect of the released metallotherapeutics is evaluated in vitro on metastatic B16F1 melanoma cells and enhanced cancer cell-killing efficacy is demonstrated upon exposure of the nanomaterials to weakly acidic conditions. The obtained results showcase the promising capabilities of the designed MSN nanocarriers for the pH-responsive delivery of metallotherapeutics and targeted treatment of cancer.

Cisplatin Prodrug-Loaded Nanoparticles Based on Physalis Mottle Virus for Cancer Therapy

Nanoparticle-based prodrugs offer an effective strategy to improve the safety and delivery of small-molecule therapeutics while reducing the risk of drug resistance. Here, we conjugated a maleimide-functionalized cisplatin prodrug containing Pt(IV) to the internal and/or external surface of virus-like particles (VLPs) derived from Physalis mottle virus (PhMV) to develop a pH-sensitive drug delivery system. The internally loaded and PEGylated VLPs (Pt-PhMVCy5.5-PEG) were taken up efficiently by cancer cells where they released platinum, presumably as a reduced, DNA-reactive Pt(II) complex, rapidly under acidic conditions in vitro (>80% in 30 h). The efficacy of the VLP-based drug delivery system was demonstrated against a panel of cancer cell lines, including cell lines resistant to platinum therapy. Furthermore, Pt-PhMVCy5.5-PEG successfully inhibited the growth of xenograft MDA-MB-231 breast tumors in vivo and significantly prolonged the survival of mice compared to free cisplatin and cisplatin-maleimide. Pt-PhMVCy5.5-PEG therefore appears promising as a prodrug to overcome the limitations of conventional platinum-based drugs for cancer therapy.

pH-Responsive and Biodegradable ZnO-Capped Mesoporous Silica Composite Nanoparticles for Drug Delivery

As a drug delivery system (DDS), traditional mesoporous silica nanoparticles (MSNs) suffer from bioaccumulation in vivo and premature drug release in systemic circulation due to low degradation rate and lack of protective gatekeeper. Herein, we developed a safe and intelligent DDS with characteristics of pH-responsive biodegradation and controlled drug release based on mesoporous silica composite nanoparticles (MSCNs) capped with ZnO quantum dots (ZnO QDs). Acidic degradable MSCNs were successfully synthesized by doping Ca²⁺ and PO₄³⁻ into the MSNs’ framework. The in vitro doxorubicin hydrochloride (DOX) release was inhibited at neutral pH 7.4 but triggered significantly at pH 5.0 due to the dissociation of ZnO caps. The internalization behavior and cytotoxicity of 4T1 cells indicated MSCNs-ZnO could efficiently deliver DOX into the cells with significant antitumor activity. Such a DDS with pH-responsive biodegradation and controlled drug release has promising potential for cancer therapy.

Amphiphilic hyperbranched polyester coated rod mesoporous silica nanoparticles for pH-responsive doxorubicin delivery

Rod-like mesoporous silica nanoparticles with pH-responsive amphiphilic hyperbranched polyester shells were prepared for doxorubicin (DOX) delivery. First, rod-shaped mesoporous silica nanoparticles (MSNs) were obtained, then hydrophobic hyperbranched polyester Boltorn H40 (H40) was grafted on their surface. The H40 coated MSNs were next treated with amine-functionalized polyethylene glycol (PEG) to achieve the hydrophilic and pH-responsive material denoted as PEG-H40-MSNs. The experimental results showed that PEG-H40-MSNs were successfully synthesized. BET analysis showed that rod MSNs exhibits a type IV standard isotherm. TEM revealed that the thin gray polymer layer was formed around the SBA-15 particle with a diameter of around 150 nm. DOX was effectively loaded, which can be released according to the ambient pH inside the cell as follow: at pH 7.4, only 9.7% of the DOX was released after 48 h; as the pH decreased to 5.5, the cumulative release reached to 49% at the same time. PEG-H40-MSNs showed less than 1.6% of hemolytic activity and a slight effect on the liver and kidney of treated mice were observed at a high disposal dosage implying negligible toxicities were caused by PEG-H40-MSNs in both in vitro hemolysis analysis and in vivo biochemical in mice. However, the in vitro cytotoxicity evaluation of the DOX-PEG-H40-MSNs showed that the cell cytotoxicity of both pure DOX and DOX-loaded PEG-H40-MSNs generally enhanced by increasing the concentration of DOX. Graphical abstract Schematic of cellular uptake and DOX release of PEG-H40-MSNs nanoparticle.

Strontium Sulfite: A New pH-Responsive Inorganic Nanocarrier to Deliver Therapeutic siRNAs to Cancer Cells

Inorganic nanoparticles hold great potential in the area of precision medicine, particularly for treating cancer owing to their unique physicochemical properties, biocompatibility and improved pharmacokinetics properties compared to their organic counterparts. Here we introduce strontium sulfite nanoparticles as new pH-responsive inorganic nanocarriers for efficient transport of siRNAs into breast cancer cells. We employed the simplest nanoprecipitation method to generate the strontium sulfite nanoparticles (SSNs) and demonstrated the dramatic roles of NaCl and d-glucose in particle growth stabilization in order to produce even smaller nanosize particles (Na-Glc-SSN) with high affinity towards negatively charged siRNA, enabling it to efficiently enter the cancer cells. Moreover, the nanoparticles were found to be degraded with a small drop in pH, suggesting their potential capability to undergo rapid dissolution at endosomal pH so as to release the payload. While these particles were found to be nontoxic to the cells, they showed higher potency in facilitating cancer cell death through intracellular delivery and release of oncogene-specific siRNAs targeting ros1 and egfr1 mRNA transcripts, than the strontium sulfite particles prepared in absence of NaCl and d-glucose, as confirmed by growth inhibition assay. The mouse plasma binding analysis by Q-TOF LC-MS/MS demonstrated less protein binding to smaller particles of Na-Glc-SSNs. The biodistribution studies of the particles after 4 h of treatment showed Na-Glc-SSNs had less off-target distribution than SSNs, and after 24 h, all siRNAs were cleared from all major organs except the tumors. ROS1 siRNA with its potential therapeutic role in treating 4T1-induced breast tumor was selected for subsequent in vivo tumor regression study, revealing that ROS1 siRNA-loaded SSNs exerted more significant anti-tumor effects than Na-Glc-SSNs carrying the same siRNA following intravenous administration, without any systemic toxicity. Thus, strontium sulfite emerged as a powerful siRNA delivery tool with potential applications in cancer gene therapy.

Chromium-Doped Zinc Gallogermanate@Zeolitic Imidazolate Framework-8: A Multifunctional Nanoplatform for Rechargeable In Vivo Persistent Luminescence Imaging and pH-Responsive Drug Release

Multifunctional theranostic nanoplatforms greatly improve the accuracy and effectiveness in tumor treatments. Much effort has been made in developing advanced optical imaging-based tumor theranostic nanoplatforms. However, autofluorescence and irradiation damage of the conventional fluorescence imaging technologies as well as unsatisfied curative effects of the nanoplatforms remain great challenges against their wide applications. Herein, we constructed a novel core-shell multifunctional nanoplatform, that is, chromium-doped zinc gallogermanate (ZGGO) near-infrared (NIR) persistent luminescent nanoparticles (PLNPs) as a core and zeolitic imidazolate framework-8 (ZIF-8) as a shell (namely ZGGO@ZIF-8). The ZGGO@ZIF-8 nanoplatform possessed dual functionalities of the autofluorescence-free NIR PersL imaging as well as the pH-responsive drug delivery, thus it has high potential in tumor theranostics. Notably, the loading content of doxorubicin (DOX) in ZGGO@ZIF-8 (LC = 93.2%) was quite high, and the drug release of DOX-loaded ZGGO@ZIF-8 was accelerated in an acidic microenvironment such as tumor cells. The ZGGO@ZIF-8 opens up a new material system in the combination of PLNPs with metal-organic frameworks and may offer new opportunities for the development of advanced multifunctional nanoplatforms for tumor theranostics, chemical sensing, and optical information storage.

Graphene Oxide Based Nanocarrier Combined with a pH-Sensitive Tracer: A Vehicle for Concurrent pH Sensing and pH-Responsive Oligonucleotide Delivery

We chemically tuned the oxidation status of graphene oxide (GO) and constructed a GO-based nanoplatform combined with a pH-sensitive fluorescence tracer that is designed for both pH sensing and pH-responsive drug delivery. A series of GOs oxidized to distinct degrees were examined to optimize the adsorption of the model drug, poly dT30. We determined that highly oxidized GO was a superior drug-carrier candidate in vitro when compared to GOs oxidized to lesser degrees. In the cell experiment, the synthesized pH-sensitive rhodamine dye was first applied to monitor cellular pH; under acidic conditions, protonated rhodamine fluoresces at 588 nm (λex=561 nm). When the dT30-GO nanocarrier was introduced into cells, a rhodamine-triggered competition reaction occurred, and this led to the release of the oligonucleotides and the quenching of rhodamine fluorescence by GO. Our results indicate high drug loading (FAM-dT30/GO=25/50 μg/mL) and rapid cellular uptake (<0.5 h) of the nanocarrier which can potentially be used for targeted RNAi delivery to the acidic milieu of tumors.