Investigation of tannic acid cross-linked onto magnetite nanoparticles for applying in drug delivery systems

Progress on green crosslinking of polysaccharide hydrogels for drug delivery and tissue engineering applications

Natural polysaccharides are being studied for their biocompatibility, biodegradability, low toxicity, and low cost in the fabrication of various hydrogel devices. However, due to their insufficient physicochemical and mechanical qualities, polysaccharide hydrogels alone are not acceptable for biological applications. Various synthetic crosslinkers have been tested to overcome the drawbacks of standalone polysaccharide hydrogels; however, the presence of toxic residual crosslinkers, the generation of toxic by-products following biodegradation, and the requirement of toxic organic solvents for processing pose challenges in achieving the desired non-toxic biomaterials. Natural crosslinkers such as citric acid, tannic acid, vanillin, gallic acid, ferulic acid, proanthocyanidins, phytic acid, squaric acid, and epigallocatechin have been used to generate polysaccharide-based hydrogels in recent years. Various polysaccharides, including cellulose, alginate, pectin, hyaluronic acid, and chitosan, have been hydrogelized and investigated for their potential in drug delivery and tissue engineering applications using natural crosslinkers. We attempted to provide an overview of the synthesis of polysaccharide-based hydrogel systems (films, complex nanoparticles, microspheres, and porous scaffolds) based on green crosslinkers, as well as a description of the mechanism of crosslinking and properties with a special emphasis on drug delivery, and tissue engineering applications.

Interacting collagen and tannic acid Particles: Uncovering pH-dependent rheological and thermodynamic behaviors

HYPOTHESIS

Biomaterials such as collagen and tannic acid (TA) particles are of interest in the development of advanced hybrid biobased systems due to their beneficial therapeutic functionalities and distinctive structural properties. The presence of numerous functional groups makes both TA and collagen pH responsive, enabling them to interact via non-covalent interactions and offer tunable macroscopic properties.

EXPERIMENT

The effect of pH on the interactions between collagen and TA particles is explored by adding TA particles at physiological pH to collagen at both acidic and neutral pH. Rheology, isothermal titration calorimetry (ITC), turbidimetric analysis and quartz crystal microbalance with dissipation monitoring (QCM-D) are used to study the effects.

FINDINGS

Rheology results show significant increase in elastic modulus with an increase in collagen concentration. However, TA particles at physiological pH provide stronger mechanical reinforcement to collagen at pH 4 than collagen at pH 7 due to the formation of a higher extent of electrostatic interaction and hydrogen bonding. ITC results confirm this hypothesis, with larger changes in enthalpy, |ΔH|, observed when collagen is at acidic pH and |ΔH| > |TΔS| indicating enthalpy-driven collagen-TA interactions. Turbidimetric analysis and QCM-D help to identify structural differences of the collagen-TA complexes and their formation at both pH conditions.

Visible Laser Light Mediated Cancer Therapy via Photothermal Effect of Tannin-Stabilized Magnetic Iron Oxide Nanoparticles

Super-paramagnetic iron oxide nanoparticles (SPIONs/Fe₃O₄) were synthesized in aqueous medium under a nitrogen atmosphere. These particles were made water-dispersible by cladding them with tannic acid (TA). The synthesized nanoparticles were characterized for their size and surface charge using HRTEM and zetasizer. It was found that the size of the particles formed was around 15 nm with almost spherical morphology and negative surface charge. Vibrating sample magnetometer (VSM) data attributed a super-paramagnetic nature to these nanoparticles. The photo-thermal dynamics of these magnetite (Fe₃O₄) nanoparticles was characterized by exciting their dispersions with laser radiation in the visible region (635 nm). Remarkably, 17 min of laser irradiation of the dispersion raised its temperature by ~25 °C (25 to 49.8 °C), whereas for the solvent, it was limited to not more than 4 °C (after 60 min). Thus, the Fe₃O₄ nanoparticles generated localized hyperthermia for potential use in cancer therapy of tumor management. The photo-thermal dynamics of these nanoparticles was investigated in-vitro for cancer therapy, and it was clearly shown that cancer cell growth was inhibited, and considerable cellular damage occurred when cells were incubated with laser-activated magnetic nanoparticles. No noticeable innate toxicity of the nanoparticles was observed on cancer cell lines. The effectiveness of these nanoparticles was studied on several malignant cell lines, and an acceptable Fe₃O₄ concentration range was subsequently determined for generating substantial cell death by hyperthermia, but not inherent toxicity. Therefore, we concluded that this nano-system is effective and less time consuming for the treatment of malignant diseases such as cancer.

Agglomerated serum albumin adsorbed protocatechuic acid coated superparamagnetic iron oxide nanoparticles as a theranostic agent

Iron oxide nanoparticles have been one of the most widely used nanomaterials in biomedical applications. However, the incomplete understanding of the toxicity mechanisms limits their use in diagnosis and treatment processes. Many parameters are associated with their toxicity such as size, surface modification, solubility, concentration and immunogenicity. Further research needs to be done to address toxicity-related concerns and to increase its effectiveness in various applications. Herein, colloidally stable nanoparticles were prepared by coating magnetic iron oxide nanoparticles (MIONPs) with protocatechuic acid (PCA) which served as a stabilizer and a linkage for a further functional layer. A new perfusion agent with magnetic imaging capability was produced by the adsorption of biocompatible passivating agent macro-aggregated albumin (MAA) on the PCA-coated MIONPs. PCA-coated MIONPs were investigated using infrared spectroscopy, thermogravimetric analysis and dynamic light scattering while adsorption of MAA was analysed by transmission electron microscopy, Fourier-transform infrared spectroscopy and x-ray diffraction methods. Magnetic measurements of samples indicated that all samples showed superparamagnetic behaviour. Cytotoxicity results revealed that the adsorption of MAA onto PCA-coated MIONPs provided an advantage by diminishing their toxicity against the L929 mouse fibroblast cell line compared to bare Fe₃O₄.

In Situ Nanoparticle Self-Assembly for Combination Delivery of Therapeutics to Non-Small Cell Lung Cancer

Chemotherapy often experiences several challenges including severe systemic toxicity and adverse effects. The combination chemotherapy arose as an effective clinical practice aimed at reducing doses of drugs to achieve synergistic actions with low toxicity. Our recent efforts demonstrated a synergistic therapeutic benefit of gambogic acid (GA) and gemcitabine (Gem) against lung cancer. However, simultaneous delivery of these two drugs at the tumor site is highly challenging. Therefore, the development of an injectable formulation that can effectively deliver both hydrophobic (GA) and hydrophilic (Gem) drugs in one formulation is a clinically unmet need. Herein, this study reports an in situ human serum albumin (HSA)- and tannic acid (TA)-mediated complexed GA and Gem nanoparticles (G-G@HTA NPs). G-G@HTA NP formation was confirmed by the particle size, Fourier transform infrared spectroscopy, and ¹H NMR spectroscopy. The superior therapeutic activity of G-G@HTA NPs was demonstrated by multiple in vitro functional assays. Additionally, G-G@HTA NPs revealed an obvious and precise targeting of tumors in vivo. The promoted and more synergistic anti-tumor efficacy of G-G@HTA NPs was attained than that of combined treatments and single drug treatments. These events have resulted in no apparent systemic and organ toxicities. Together, this study suggests that in situ HSA-TA-based combinatorial treatment strategy is a suitable approach for application in lung cancer treatment.

Sensing and Imaging of PPi in vivo using Lanthanide-based Second Near-infrared Luminescent Probes

pathological changes. Here, we reported a luminescent nanoprobe for the detection and imaging of PPi in vivo based on a lanthanide nanoparticle with luminescence at the second near-infrared window modified...

Reversibly-regulated drug release using poly(tannic acid) fabricated nanocarriers for reduced secondary side effects in tumor therapy

Numerous nanocarriers with pH-responsive properties have been designed and fabricated to reduce the adverse side effects of traditional chemotherapeutics, but these traditional nanocarriers are rarely reversible; this may cause "secondary" side effects on normal tissues, because the nanocarriers cannot be sealed again to prevent the leakage of incompletely released drugs after re-entering blood circulation. To overcome these limitations, we report herein the synthesis of a reversibly pH-responsive drug delivery system, which can achieve regulated drug release in a "release-stop-release" manner corresponding to changes in pH. Specifically, poly(tannic acid) as the "gatekeeper" was firstly deposited and polymerized on the surface of mesoporous silica nanoparticles (MSNs) via a modified mussel-inspired method similar to dopamine, and the formed polymer shell can be easily decorated with a targeting ligand HER2 antibody for the selective delivery of drugs to specific cells. The resulting nanocomposites exhibited good colloidal stability, good biocompatibility, high drug loading capacity and accurate HER2 antibody mediated targeting ability. Interestingly, a series of experiments fully demonstrated that the fabricated nanocomposites possessed intelligent reversible pH-responsive controlled release behavior through adjusting the density of the "gatekeeper" under different pH conditions, thereby achieving reversible switching from "on" to "off". Furthermore, in vitro and in vivo experiments verified that the fabricated targeting nanoparticles could efficiently inhibit tumor growth with minimal side effects. Meanwhile, these nanocarriers exhibited excellent reusability, in vitro cytotoxicity and minimal in vivo myocardial damage. Collectively, the reversible pH-operated nanovalve on the MSNs constructed here could serve as a nanoplatform to solve the problem of "secondary" side effects caused by residual drugs in irreversible "gatekeeper" systems.

Development of a safe and efficient gene delivery system based on a biodegradable tannic acid backbone

Finding a safe and efficient gene delivery vector is a major international challenge facing the development of gene therapy. Tannic acid (TA) is a natural cross-linker owing to its hydroxyl and carboxyl groups that can interact with biopolymers for different biomaterial design. In this work, three polyethyleneimine-modified TA polymers were prepared, and the polymers were characterized by FTIR, UV-vis, elemental analysis and ¹H NMR. The potential of PTAs as gene vector was studied in vitro, including DNA loading capacity, DNA protection ability and biocompatibility. In addition, the particle size, zeta potential, DNA encapsulation efficiency, cell uptake and transfection efficiency of the PTA-pDNA polyplexes were also studied. The results showed that PTA2k and PTA30k could completely condense DNA at N/P of 2, and PTA600 could only completely condense DNA at N/P of 50. The PTA/pDNA polyplexes could protect DNA from degrading by DNA enzymes and could be efficiently uptaked by cells. Biocompatibility assay showed that PTA had no significant cytotoxicity and effect on cell proliferation compared to PEI. At low N/P ratios of 1-4, PTA showed higher transfection efficiency than PEI, and the transfection efficiency increased with the increase of PEI molecular weight in PTA. At N/P of 3, PTA30k showed the highest transfection efficiency of 23.8%, while PEI30k showed only 6.7%. These results indicate that PTA is a promising candidate vector for safe and efficient gene delivery.

Synthesis and modification of crystalline SBA-15 nanowhiskers as a pH-sensitive metronidazole nanocarrier system

Clinical resistance to drugs and diminution in their side effects have become great issues for pharmacologists. In veterinary medicine, parasites like Trichomonas gallinae are of veterinary, hygienic and economic importance and can be treated by metronidazole. Unfortunately, scientific evidence has been reported about its resistance and serious side effects in trichomoniasis. In this research, it was attempted to introduce a new procedure to lower side effects of the drug molecules and also, enhance the treatment of disease. Whisker-formed SBA-15 nanoparticles were utilized for the first time in this issue. They had mesoporous structures which metronidazole molecules could be trapped in them. Additionally, these crystalline nanowhiskers were modified with tannic acid to make the release process better. The branches of tannic acid covered the opening of pores in crystalline SBA-15 nanowhiskers and restricted the drug from fast release. It caused a controlled metronidazole release in the smart drug delivery. These nanocarriers were completely tested by several experiments. Whisker-like SBA-15 nanocrystals had a mesopore volume of 0.5931 cm³/g, pore diameter of 6.06 nm and surface area of 491.38 m²/g. Based on TGA analysis, 10% of tannic acid was coated on the crystalline nanowhiskers during the modification. The metronidazole content and entrapment efficiency of final nanocarriers was 28.56% and 71.40%, respectively. The decomposition of tannic acid in lower pHs made whisker-like SBA-15@tannic acid nanocrystals be pH-responsive which can be used for other applications in the pharmacology. In-vitro study revealed that the minimal lethal concentration of nanocarriers was 0.5 mg/mL for 180 min.