Magnetically controlled drug delivery and hyperthermia effects of core-shell Cu@Mn3O4 nanoparticles towards cancer cells in vitro

Recent increase in the integration of nanotechnology and nanosciences to the biomedical sector fetches the human wellness through the development of sustainable treatment methodologies for cancerous tumors at all stages of their initiation and progression. This involves the development of multifunctional theranostic probes that effectively support for the early cancer diagnosis, avoiding non-target cell toxicity, controlled and customized anticancer drug release etc. Therefore, to advance the field of nanotechnology-based sustainable cancer treatment, we fabricated and tested the efficacy of anticancer drug-loaded magnetic hybrid nanoparticles (NPs) towards in vitro cell culture systems. The developed conjugate of NPs was incorporated with the functions of both controlled drug delivery and heat-releasing ability using Mn3O4 (manganese oxide) magnetic core with Cu shell encapsulated within trimethyl chitosan (TMC) biopolymer. On characterization, the Cu@Mn3O4-TMC NPs were confirmed to have an approximate size of 130 nm with full agglomeration (as observed by the HRTEM) and crystal size of 92.95 ± 18.38 nm with tetragonal hausmannite phase for Mn3O4 spinel structure (XRD). Also, the UV-Vis and FTIR analysis provided the qualitative and quantitative effects of 5-fluororacil (5-Fu) anticancer drug loading (max 68 %) onto the Cu@Mn3O4-TMC NPs. The DLS analysis indicated for the occurrence of no significant changes to the particle size (around 100 nm) of Cu@Mn3O4-TMC due to the solution dispersion thereby confirming for the aqueous stability of developed NPs. In addition, the magnetization values of Cu@Mn3O4-TMC NPs were measured to be 34 emu/g and a blocking temperature of 42 K. Further tests of magnetic hyperthermia by the Cu@Mn3O4-TMC/5-Fu NPs provided that the heat-releasing capacity (% ΔT at 15 min) increases with that of increased frequency, i.e. 28 % (440 Hz) > 22.6 % (240 Hz) > 18 % (44 Hz), and the highest specific power loss (SPL) value observed to be 488 W/g for water. Moreover, the 5-Fu drug release studies indicate that the release is high at a pH of 5.2 and almost all the loaded drug is getting delivered under the influence of the external magnetic field (430 Hz) due to the influence of both Brownian-rotation and Néel relaxation heat-mediated mechanism. The pharmacokinetic drug release studies have suggested for the occurrence of more than one model, i.e. First-order, Higuchi (diffusion), and Korsemeyer-Peppas (non-Fickian), in addition to hyperthermia. Finally, the in vitro cell culture systems (MCF-7 cancer and MCF-10 non-cancer) helped to differentiate the physiological changes due to the effects of hyperthermia and 5-Fu drug individually and as a combination of both. The observed differences of cell viability losses among both cell types are measured and discussed with the expression of heat shock proteins (HSPs) by the MCF-10 cells as against the MCF-7 cancer cells. We believe that the results generated in this project can be helpful for the designing of new cancer therapeutic models with nominal adverse effects on healthy normal cells and thus paving a way for the treatment of cancer and other deadly diseases in a sustainable manner.

Multiple Regulation Effects of Ammonium Acetate on ZnO Growth Process in Chemical Bath Deposition

Chemical bath deposition method has been used to synthesize a variety of ZnO morphology structures. However, the specificity and interaction of acetate and ammonium ions with ZnO crystal during the growth process remain elusive. This study contributes to understand the roles of ammonium acetate on the growth mechanism of ZnO in Zn(NO₃ )₂ -HMTA system. The growth process indicates that the nucleation experienced Zn²⁺ -layered basic zinc salts (LBZs)-ZnO process, while the self-assembled unit changed from urchin-shaped, rod-shaped to a fully coupled twin-shaped structure with increasing ammonium acetate concentration. Ammonium acetate dominates the growth process by combing the ligand-ligand interaction of acetate ions binding to the same Zn-rich (0001) polar surface and ammonium ions regulating hexamethylenetetramine (HMTA) hydrolysis. Relatively regular hexagonal wurtzite structure and a dissolve-renucleation-regrowth process which retains the twin-shaped template and renucleates at the same position are observed at ∼10 mM ammonium acetate. Photoelectrochemistry (PEC) measurements show that the uniform hexagonal ZnO rods (Y-10, the sample named as Y-x (x represents x mM ammonium acetate, herein, x is 10 mM)) have a maximum photocurrent density of 1.54 mA cm^-2 at 1.23 V (vs. RHE), much higher than that of the dumbbell-shaped ZnO rods (Y-50, 0.20 mA cm^-2 ) at the same voltage. These results provide a further explanation of morphology regulation mechanisms on ZnO synthesis processes and pave the road for more practical applications.

Chiral Nanoceramics

The study of different chiral inorganic nanomaterials has been experiencing rapid growth during the past decade, with its primary focus on metals and semiconductors. Ceramic materials can substantially expand the range of mechanical, optical, chemical, electrical, magnetic, and biological properties of chiral nanostructures, further stimulating theoretical, synthetic, and applied research in this area. An ever-expanding toolbox of nanoscale engineering and self-organization provides a chirality-based methodology for engineering of hierarchically organized ceramic materials. However, fundamental discoveries and technological translations of chiral nanoceramics have received substantially smaller attention than counterparts from metals and semiconductors. Findings in this research area are scattered over a variety of sources and subfields. Here, the diversity of chemistries, geometries, and properties found in chiral ceramic nanostructures are summarized. They represent a compelling materials platform for realization of chirality transfer through multiple scales that can result in new forms of ceramic materials. Multiscale chiral geometries and the structural versatility of nanoceramics are complemented by their high chiroptical activity, enantioselectivity, catalytic activity, and biocompatibility. Future development in this field is likely to encompass chiral synthesis, biomedical applications, and optical/electronic devices. The implementation of computationally designed chiral nanoceramics for biomimetic catalysts and quantum information devices may also be expected.

Platform for Screening Abiotic/Biotic Interactions Using Indicator Displacement Assays

This paper describes novel adaptations of optically sectioned planar format assays to screen compounds for their affinities to materials surfaces. The novel platform, which we name optically sectioned indicator displacement assays (O-IDA), makes use of displaceable dyes in a format adaptable to high-throughput multiwell plate technologies. We describe two approaches: the first being where the dye exhibits fluorescence in both the surface bound and unbound state and the second, where fluorescence is lost upon displacement of the dye from the surface. Half maximal inhibitory concentration (IC₅₀), binding affinity (K_i), and binding free energy (ΔG_ads) values can be extracted from the raw data. Representative biomolecules were tested for interactions with silica in an aqueous environment and ZnO(0001)-Zn and (10-10) facets in a nonaqueous environment. We provide the first experimental values for both the binding of small molecules to silica and the facet-dependent ZnO binding affinity of key amino acids associated with ZnO-specific oligopeptides. The specific data will be invaluable to those studying interactions at interfaces both experimentally and computationally. O-IDA provides a general framework for the high-throughput screening of molecule binding to materials surfaces, which has important applications in drug delivery, (bio-) catalysis, biosensing, and biomaterial engineering.

Experimental and theoretical tools to elucidate the binding mechanisms of solid-binding peptides

The interactions between biomolecules and solid surfaces play an important role in designing new materials and applications which mimic nature. Recently, solid-binding peptides (SBPs) have emerged as potential molecular building blocks in nanobiotechnology. SBPs exhibit high selectivity and binding affinity towards a wide range of inorganic and organic materials. Although these peptides have been widely used in various applications, there is a need to understand the interaction mechanism between the peptide and its material substrate, which is challenging both experimentally and theoretically. This review describes the main characterisation techniques currently available to study SBP-surface interactions and their contribution to gain a better insight for designing new peptides for tailored binding.

Interactions between Metal Oxides and Biomolecules: from Fundamental Understanding to Applications

Metallo-oxide (MO)-based bioinorganic nanocomposites promise unique structures, physicochemical properties, and novel biochemical functionalities, and within the past decade, investment in research on materials such as ZnO, TiO₂, SiO₂, and GeO₂ has significantly increased. Besides traditional approaches, the synthesis, shaping, structural patterning, and postprocessing chemical functionalization of the materials surface is inspired by strategies which mimic processes in nature. Would such materials deliver new technologies? Answering this question requires the merging of historical knowledge and current research from different fields of science. Practically, we need an effective defragmentation of the research area. From our perspective, the superficial accounting of material properties, chemistry of the surfaces, and the behavior of biomolecules next to such surfaces is a problem. This is particularly of concern when we wish to bridge between technologies in vitro and biotechnologies in vivo. Further, besides the potential practical technological efficiency and advantages such materials might exhibit, we have to consider the wider long-term implications of material stability and toxicity. In this contribution, we present a critical review of recent advances in the chemistry and engineering of MO-based biocomposites, highlighting the role of interactions at the interface and the techniques by which these can be studied. At the end of the article, we outline the challenges which hamper progress in research and extrapolate to developing and promising directions including additive manufacturing and synthetic biology that could benefit from molecular level understanding of interactions occurring between inanimate (abiotic) and living (biotic) materials.

Thermodynamic Study of Interactions Between ZnO and ZnO Binding Peptides Using Isothermal Titration Calorimetry

While material-specific peptide binding sequences have been identified using a combination of combinatorial methods and computational modeling tools, a deep molecular level understanding of the fundamental principles through which these interactions occur and in some instances modify the morphology of inorganic materials is far from being fully realized. Understanding the thermodynamic changes that occur during peptide-inorganic interactions and correlating these to structural modifications of the inorganic materials could be the key to achieving and mastering control over material formation processes. This study is a detailed investigation applying isothermal titration calorimetry (ITC) to directly probe thermodynamic changes that occur during interaction of ZnO binding peptides (ZnO-BPs) and ZnO. The ZnO-BPs used are reported sequences G-12 (GLHVMHKVAPPR), GT-16 (GLHVMHKVAPPR-GGGC), and alanine mutants of G-12 (G-12A6, G-12A11, and G-12A12) whose interaction with ZnO during solution synthesis studies have been extensively investigated. The interactions of the ZnO-BPs with ZnO yielded biphasic isotherms comprising both an endothermic and an exothermic event. Qualitative differences were observed in the isothermal profiles of the different peptides and ZnO particles studied. Measured ΔG values were between -6 and -8.5 kcal/mol, and high adsorption affinity values indicated the occurrence of favorable ZnO-BP-ZnO interactions. ITC has great potential in its use to understand peptide-inorganic interactions, and with continued development, the knowledge gained may be instrumental for simplification of selection processes of organic molecules for the advancement of material synthesis and design.