Nanoporous anodic titanium dioxide layers as potential drug delivery systems: Drug release kinetics and mechanism

The smart nanocarrier containing zein/starch co-biopolymers enhanced by graphitic carbon nitride; exploring opportunities in brain cancer treatment

In this investigation, we present an innovative pH-responsive nanocomposite designed to address challenges associated with using 5-Fluorouracil (5-FU) in cancer therapy. The nanocomposite containing zein (Z), starch (S), and graphitic carbon nitride (g-C3N4) macromolecules is synthesized by a water-in-oil-in-water (W/O/W) double emulsion technique, serving as a carrier for 5-FU. The S/Z hydrogel matrix's entrapment and loading efficiency are greatly improved by adding g-C3N4 nanosheets, reaching noteworthy values of 45.25 % and 86.5 %, respectively, for drug loading efficiency and entrapment efficiency. Characterization through FTIR and XRD validates the successful loading of 5-FU, elucidating the chemical bonding within the nanocomposite and crystalline characteristics. Structural analysis using FESEM, along with DLS and zeta potential measurements, reveals an average nanocomposite size of 193.48 nm, indicating a controlled structure, and a zeta potential of -42.32 mV, signifying a negatively charged surface. Studies on the in vitro release of drugs reveal that 5-FU is delivered more effectively and sustainably in acidic environments than in physiological circumstances. This highlights the fact that the created nanocarrier is pH-sensitive. Modeling release kinetics involves finding the right mathematical conditions representing underlying physicochemical processes. Employing curve-fitting techniques, predominant release mechanisms are identified, and optimal-fitting kinetic models are determined. The Baker kinetic model performed best at pH 7.4, indicating that the leading cause of the drug release was polymer swelling. In contrast, the Higuchi model was most accurate for drug release at pH 5.4, illuminating the diffusion and dissolution mechanisms involved in diffusion. To be more precise, the mechanism of release at pH 7.4 and 5.4 was anomalous transport (dissolution-controlled), according to the Korsmeyer-Peppas mathematical model. The pH-dependent swelling and degradation behavior of S/Z/g-C3N4@5-FU nanocomposite showed higher swelling and faster degradation in acidic environments compared to neutral conditions. Crucially, outcomes from the MTT test affirm the significant cytotoxicity of the 5-FU-loaded nanocomposite against U-87 MG brain cancer cells, while simultaneously indicating non-toxicity towards L929 fibroblast cells. These cumulative findings underscore the potential of the engineered S/Z/g-C3N4@5-FU as a productive and targeted therapeutic approach for cancer cells.

Surface Modification of Mesoporous Silica Nanoparticles for Application in Targeted Delivery Systems of Antitumour Drugs

The problem of tumour therapy has attracted the attention of many researchers for many decades. One of the promising strategies for the development of new dosage forms to improve oncology treatment efficacy and minimise side effects is the development of nanoparticle-based targeted transport systems for anticancer drugs. Among inorganic nanoparticles, mesoporous silica deserves special attention due to its outstanding surface properties and drug-loading capability. This review analyses the various factors affecting the cytotoxicity, cellular uptake, and biocompatibility of mesoporous silica nanoparticles (MSNs), constituting a key aspect in the development of safe and effective drug delivery systems. Special attention is paid to technological approaches to chemically modifying MSNs to alter their surface properties. The stimuli that regulate drug release from nanoparticles are also discussed, contributing to the effective control of the delivery process in the body. The findings emphasise the importance of modifying MSNs with different surface functional groups, bio-recognisable molecules, and polymers for their potential use in anticancer drug delivery systems.

Enhanced delivery of doxorubicin for breast cancer treatment using pH-sensitive starch/PVA/g-C3N4 hydrogel

This study introduces a starch/PVA/g-C3N4 nanocarrier hydrogel for pH-sensitive DOX delivery in breast cancer. DOX was loaded into the nanocarrier with 44.75 % loading efficiency and 88 % Entrapment Efficiency. The release of DOX from the starch/PVA/g-C3N4 hydrogel was pH-sensitive: DOX was released faster in the acidic environment pertinent to cancer tumors (with a pH level of 5.4) than in the surrounding regular tissue environment carrying a more neutral environment (pH 7.4). The release kinetics analysis, encompassing zero-order, first-order, Higuchi, and Korsmeyer-Peppas models, revealed significant fitting with the Higuchi model at both pH 5.4 (R2 = 0.99, K = 9.89) and pH 7.4 (R2 = 0.99, K = 5.70) levels. Finally, we found that hydrogel was less damaging to healthy cells and more specific to apoptotic cells than the drug's free form. The starch/PVA/g-C3N4 hydrogel had low toxicity for both normal cells and breast cancer cells, whereas DOX loaded into the starch/PVA/g-C3N4 hydrogel had higher toxicity for cancer cells than the DOX-only control samples, and led to specific high apoptosis for cancer cells. The study suggests that DOX can be loaded into a starch/PVA/g-C3N4 hydrogel to improve the specificity of the drug's release in cancer tumors or in vitro breast cancer cells.

Nanoscale Topography of Anodic TiO2 Nanostructures Is Crucial for Cell-Surface Interactions

Anodic titanium dioxide (TiO2) nanostructures, i.e., obtained by electrochemical anodization, have excellent control over the nanoscale morphology and have been extensively investigated in biomedical applications owing to their sub-100 nm nanoscale topography range and beneficial effects on biocompatibility and cell interactions. Herein, we obtain TiO2 nanopores (NPs) and nanotubes (NTs) with similar morphologies, namely, 15 nm diameter and 500 nm length, and investigate their characteristics and impact on stem cell adhesion. We show that the transition of TiO2 NPs to NTs occurs via a pore/wall splitting mechanism and the removal of the fluoride-rich layer. Furthermore, in contrast to the case of NPs, we observe increased cell adhesion and proliferation on nanotubes. The enhanced mesenchymal stem cell adhesion/proliferation seems to be related to a 3-fold increase in activated integrin clustering, as confirmed by immunogold labeling with β1 integrin antibody on the nanostructured layers. Moreover, computations of the electric field and surface charge density show increased values at the inner and outer sharp edges of the top surfaces of the NTs, which in turn can influence cell adhesion by increasing the bridging interactions mediated by proteins and molecules in the environment. Collectively, our results indicate that the nanoscale surface architecture of the lateral spacing topography can greatly influence stem cell adhesion on substrates for biomedical applications.

Controlled drug delivery from chitosan-coated heparin-loaded nanopores anodically grown on nitinol shape-memory alloy

Nitinol (NiTi shape-memory alloy) is an interesting candidate in various medical applications like dental, orthopedic, and cardiovascular devices, owing to its unique mechanical behaviors and proper biocompatibility. The aim of this work is the local controlled delivery of a cardiovascular drug, heparin, loaded onto nitinol treated by electrochemical anodizing and chitosan coating. In this regard, the structure, wettability, drug release kinetics, and cell cytocompatibility of the specimens were analyzed in vitro. The two-stage anodizing process successfully developed a regular nanoporous layer of Ni-Ti-O on nitinol, which considerably decreased the sessile water contact angle and induced hydrophilicity. The application of the chitosan coatings controlled the release of heparin mainly by a diffusional mechanism, where the drug release mechanisms were evaluated by the Higuchi, first-order, zero-order, and Korsmeyer-Pepass models. Human umbilical cord endothelial cells (HUVECs) viability assay also showed the non-cytotoxicity of the samples, so that the best performance was found for the chitosan-coated samples. It is concluded that the designed drug delivery systems are promising for cardiovascular, particularly stent applications.

Biological Activity and Thrombogenic Properties of Oxide Nanotubes on the Ti-13Nb-13Zr Biomedical Alloy

The success of implant treatment is dependent on the osseointegration of the implant. The main goal of this work was to improve the biofunctionality of the Ti-13Nb-13Zr implant alloy by the production of oxide nanotubes (ONTs) layers for better anchoring in the bone and use as an intelligent carrier in drug delivery systems. Anodization of the Ti-13Nb-13Zr alloy was carried out in 0.5% HF, 1 M (NH₄)₂SO₄ + 2% NH₄F, and 1 M ethylene glycol + 4 wt.% NH₄F electrolytes. Physicochemical characteristics of ONTs were performed by high-resolution electron microscopy (HREM), X-ray photoelectron spectroscopy (XPS), and scanning Kelvin probe (SKP). Water contact angle studies were conducted using the sitting airdrop method. In vitro biological properties and release kinetics of ibuprofen were investigated. The results of TEM and XPS studies confirmed the formation of the single-walled ONTs of three generations on the bi-phase (α + β) Ti-13Nb-13Zr alloy. The ONTs were composed of oxides of the alloying elements. The proposed surface modification method ensured good hemolytic properties, no cytotoxity for L-929 mouse cells, good adhesion, increased surface wettability, and improved athrombogenic properties of the Ti-13Nb-13Zr alloy. Nanotubular surfaces allowed ibuprofen to be released from the polymer matrix according to the Gallagher-Corrigan model.

Controlled Delivery of Celecoxib-β-Cyclodextrin Complexes from the Nanostructured Titanium Dioxide Layers

Considering the potential of nanostructured titanium dioxide layers as drug delivery systems, it is advisable to indicate the possibility of creating a functional drug delivery system based on anodic TiO₂ for celecoxib as an alternative anti-inflammatory drug and its inclusion complex with β-cyclodextrin. First, the optimal composition of celecoxib-β-cyclodextrin complexes was synthesized and determined. The effectiveness of the complexation was quantified using isothermal titration calorimetry (ITC), differential scanning calorimetry (DSC), infrared spectroscopy (FT-IR) nuclear magnetic resonance (¹H NMR), and scanning electron microscopy (SEM). Then, nanostructured titanium dioxide layers (TiO₂) were synthesized using the electrochemical oxidation technique. The TiO₂ layers with pore diameters of 60 nm and layer thickness of 1.60 µm were used as drug delivery systems. The samples were modified with pure celecoxib and the β-cyclodextrin-celecoxib complex. The release profiles shown effective drug release from such layers during 24 h. After the initial burst release, the drug was continuously released from the pores. The presented results confirm that the use of nanostructured TiO₂ as a drug delivery system can be effectively used in more complicated systems composed of β-cyclodextrin-celecoxib complexes, making such drugs available for pain treatment, e.g., for orthopedic surgeries.

Green synthesis of chitosan/polyacrylic acid/graphitic carbon nitride nanocarrier as a potential pH-sensitive system for curcumin delivery to MCF-7 breast cancer cells

A novel pH-sensitive nanocarrier containing chitosan (CS), polyacrylic acid (PAA), and graphitic carbon nitride (g-C₃N₄) was designed via water/oil/water (W/O/W) emulsification to administer curcumin (CUR) drug. g-C₃N₄ nanosheets with a high surface area and porous structure were produced via simple one-step pyrolysis process using thiourea as precursor, and incorporated into CS/PAA hydrogel. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR) were used to assess the crystalline structure of the nanocarrier and the interactions between its components, respectively. Scanning electron microscopy (SEM) images revealed a spherical structure and confirmed the g-C₃N₄ impregnation into the CS/PAA matrix. Zeta potential and dynamic light scattering (DLS) provided information about the surface charge and average size distribution. High CUR loading and entrapment efficiencies were obtained, which were further improved upon addition of g-C₃N₄. The release kinetics of drug-loaded CS/PAA/g-C₃N₄ nanocomposites were investigated at pH = 5.4 and pH = 7.4, and the results showed an excellent controlled pH-sensitive release profile. Cell apoptosis and in vitro cytotoxicity were investigated using flow cytometry and MTT analyses. CS/PAA/g-C₃N₄/CUR resulted in the highest rate of apoptosis in MCF-7 breast cancer cells, demonstrating the excellent nanocomposite efficacy in eliminating cancerous cells. CS/PAA hydrogel coated with g-C₃N₄ shows great potential for pH-sensitive controlled drug release.

Green synthesized polyvinylpyrrolidone/titanium dioxide hydrogel nanocomposite modified with agarose macromolecules for sustained and pH-responsive release of anticancer drug

Cancer, as one of the most challenging diseases of the last century, has a significant number of patients and deaths every year. Various strategies have been explored for the treatment of cancer. Chemotherapy is one of the methods of treating cancer. Doxorubicin is one of the compounds used in chemotherapy to kill cancer cells. Due to their unique properties and low toxicity, metal oxide nanoparticles are effective in combination therapy and increase the effectiveness of anti-cancer compounds. The limited in vivo circulatory period, poor solubility, and inadequate penetration of doxorubicin (DOX) restrict its use in cancer treatment, notwithstanding its attractive characteristics. It is possible to circumvent some of the difficulties in cancer therapy by using green synthesized pH-responsive nanocomposite consisting of polyvinylpyrrolidone (PVP), titanium dioxide (TiO₂) modified with agarose (Ag) macromolecules. TiO₂ incorporation into the PVP-Ag nanocomposite resulted in limited increased loading and encapsulation efficiencies from 41 % to 47 % and 84 % to 88.5 %, respectively. DOX diffusion among normal cells is prevented by the PVP-Ag-TiO₂ nanocarrier at pH = 7.4, though the acidic intracellular microenvironments activate the PVP-Ag-TiO₂ nanocarrier at pH = 5.4. Characterization of the nanocarrier was performed using X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrophotometry, field emission scanning electron microscopy (FE-SEM), dynamic light scattering (DLS), and zeta potential. The average particle size and the zeta potential of the particles showed values of 349.8 nm and +57 mV, respectively. In vitro release after 96 h showed a release rate of 92 % at pH 7.4 and a release rate of 96 % at pH 5.4. Meanwhile, the initial release after 24 h was 42 % for pH 7.4 and 76 % for pH 5.4. As shown by an MTT analysis on MCF-7 cells, the toxicity of DOX-loaded PVP-Ag-TiO₂ nanocomposite was substantially greater than that of unbound DOX and PVP-Ag-TiO₂. After integrating TiO₂ nanomaterials into the PVP-Ag-DOX nanocarrier, flow cytometry data showed a greater stimulation of cell death. These data indicate that the DOX-loaded nanocomposite is a suitable alternative for drug delivery systems.

Titanium (IV) oxide anatase nanoparticles as vectors for diclofenac: assessing the antioxidative responses to single and combined exposures in the aquatic macrophyte Egeria densa

Titanium dioxide, frequently used in commonplace products, is now regularly detected in aquatic environments. Understanding its toxic effects on native biota is essential. However, combined toxicity with commonly occurring pollutants, such as the pharmaceutical diclofenac, may provide more insight into environmental situations. Therefore, the present study aimed to evaluate the effects of titanium dioxide and diclofenac, individually and combined, on the macrophyte Egeria densa. Diclofenac uptake and removal by the macrophyte were assessed. Diclofenac and titanium dioxide were mixed prior to exposure to allow binding, which was assessed. Toxicity of the individual compounds and the combination was evaluated by assaying enzymes as bioindicators of biotransformation and the antioxidative system. Cytosolic glutathione S-transferase and glutathione reductase activities were increased by diclofenac, titanium dioxide, and the combination. Both enzymes' activities were more significantly elevated by diclofenac and the combination than nanoparticles alone. Microsomal glutathione S-transferase was unaffected by diclofenac exposure but inhibited with titanium dioxide and the mixture. Diclofenac elicited the most significant response. Based on the data, the cytosolic enzymes effectively prevented damage.

Assessment of synthesized chitosan/halloysite nanocarrier modified by carbon nanotube for pH-sensitive delivery of curcumin to cancerous media

Constructing a system to carry medicine for more effective remedy of cancer has been a leading challenge, as the number of cancer cases continues to increase. In this present research, a curcumin-loaded chitosan/halloysite/carbon nanotube nanomixture was fabricated by means of water/oil/water emulsification method. The drug loading efficiency (DL) and entrapment efficiency (EE), as a result, reached 42 % and 88 %, respectively and FTIR and XRD analysis confirmed the bonding between the drug and nanocarrier. Morphological observation through FE-SEM and characterization through DLS analysis demonstrated that the average size of nanoparticles is 267.37 nm. Assessment of release within 96 h in pH 7.4 and 5.4 showed sustained release. For more investigation, release data was analyzed by diverse kinetic models to understand the mechanism in the release procedure. An MTT assay was also carried out, and the results illustrated apoptosis induction on MCF-7 cells and exhibited ameliorated cytotoxicity of the drug-loaded nanocomposite compared to the free curcumin. These findings suggest that the unique pH-responsive chitosan/halloysite/carbon nanotube nanocomposite might make a good option for drug delivery systems, particularly for the cancer treatment.

Synthesis and characterization of a novel, pH-responsive sustained release nanocarrier using polyethylene glycol, graphene oxide, and natural silk fibroin protein by a green nano emulsification method to enhance cancer treatment

In this study, for the first time, by employing a simple and efficient double nano-emulsification method and using sweet almond oil as the organic phase, polyethylene glycol (PEG)/graphene oxide (GO)/silk fibroin (SF) hydrogel-nanocomposite was synthesized. The aim of the research was to fabricate a biocompatible targeted pH-sensitive sustained release carrier, improve the drug loading capacity and enhance the anticancer effect of doxorubicin (DOX) drug. The obtained values for the entrapment (%EE) and loading efficacy (%LE) were 87.75 ± 0.7 % and 46 ± 1 %, respectively, and these high values were due to the use of GO with a large specific surface area and the electrostatic interaction between the drug and SF. The Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the presence of all the components in the nanocomposite and the suitable interaction between them. Based on the results of dynamic light scattering analysis (DLS) and zeta potential analysis, the mean size of the carrier particles and its surface charge were 293.7 nm and -102.9 mV, respectively. The high negative charge was caused by the presence of hydroxyl groups in GO and SF and it caused proper stability of the nanocomposite. The spherical core-shell structure with its homogeneous surface was also observed in the field emission scanning electron microscopy (FE-SEM) image. The cumulative release percentage of the nanocarrier reached 95.75 after 96 h and it is higher in the acidic environment at all times. The results of fitting the release data to the kinetic models suggested that the mechanism of release was dissolution-controlled anomalous at pH 7.4 and diffusion-controlled anomalous at pH 5.4. The results of 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay and flow cytometry showed an increase in toxicity on MCF-7 cells and improved apoptotic cell death compared to the free drug. Consequently, the findings of this research introduced and confirmed PEG/GO/SF nanocomposite as an attractive novel drug delivery system for pH-sensitive and sustained delivery of chemotherapeutic agents in biomedicine.

Development of chitosan/halloysite/graphitic‑carbon nitride nanovehicle for targeted delivery of quercetin to enhance its limitation in cancer therapy: An in vitro cytotoxicity against MCF-7 cells

Although quercetin (QC) has valuable advantages, its low water solubility and poor permeability have limited its utilization as an anticancer drug. In this study, hydrogel nanocomposite of chitosan (CS), halloysite (HNT), and graphitic‑carbon nitride (g-C3N4) was prepared and loaded by QC using a water in oil in water emulsification process to attain QC sustained-release. Using g-C3N4 in the HNT/CS hydrogel solution enhanced the entrapment effectiveness (EE %) by up to 86 %. The interactions between QC and nanoparticles caused the nanocomposite pH-responsive behavior that assists in minimizing the side effect of the anticancer agent by controlling the burst release of QC at neutral conditions. According to DLS analysis, the size of the QC-loaded nanovehicle was 454.65 nm, showing that nanoparticles are highly monodispersed, which also was approved by FE-SEM. Additionally, Zeta potential value for the fabricated drug-loaded nanocarrier is +55.23 mV displaying that nanoparticles have good stability. The hydrogel nanocomposite structure's completeness was shown by FTIR pattern, and quercetin was included into the designed delivery system based on XRD data. Besides, the drug release profile indicated that a targeted sustained-release and pH-sensitive release of anticancer drug with the 96-hour extended-release were noticed. In order to comprehend the process of QC release at pH 5.4 and 7.4, four kinetic models were employed to find the best-suited model according to the acquired release data. Finally, the MTT experiment revealed considerable cytotoxicity against breast cancer cells, MCF-7 cell line was experimented in vitro, for the CS/HNT/g-C3N4 targeted delivery system in comparison to QC as a free drug. According to the above description, the CS/HNT/g-C3N4 delivery platform is a unique pH-sensitive drug delivery system for anticancer purposes that improves loading as well as sustained-release of quercetin.

Electrochemistry at Krakowian research institutions

The electrochemistry research team activity from Poland is marked by significant increase in the last 20 years. The joining of European Community in 2004 gives an impulse for the development of Polish science. The development of electrochemistry has been stimulated by cooperation with industry and the establishment of technology transfer centers, technology parks, business incubators, etc. and the mostly by simplified international collaborations. Five research institutions from Krakow reports work in the field of electrochemistry. The achievements of all teams are briefly described.

pH-Responsive PVA-Based Nanofibers Containing GO Modified with Ag Nanoparticles: Physico-Chemical Characterization, Wound Dressing, and Drug Delivery

Site-specific drug delivery and carrying repairing agents for wound healing purposes can be achieved using the intertwined three-dimensional structure of nanofibers. This study aimed to optimize and fabricate poly (vinyl alcohol) (PVA)-graphene oxide (GO)-silver (Ag) nanofibers containing curcumin (CUR) using the electrospinning method for potential wound healing applications. Fourier Transform Infrared (FTIR) spectrophotometry, X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Dynamic Light Scattering (DLS), and zeta potential were used to characterize the nanostructures. The mechanical properties of the nanostructures were subsequently examined by tensile strength and elongation test. As shown by MIC analysis of E. coli and S. aureus bacteria, the fabricated nanofibers had superior inhibitory effects on the bacteria growth. Ag nanoparticles incorporation into the nanofibers resulted in increased loading and encapsulation efficiencies from 21% to 56% and from 61% to 86%, respectively. CUR release from PVA/GO-Ag-CUR nanofiber at pH 7.4 was prevented, while the acidic microenvironment (pH 5.4) increased the release of CUR from PVA/GO-Ag-CUR nanofiber, corroborating the pH-sensitivity of the nanofibers. Using the in vitro wound healing test on NIH 3T3 fibroblast cells, we observed accelerated growth and proliferation of cells cultured on PVA/GO-Ag-CUR nanofibers.

Chitosan/Gamma-Alumina/Fe3O4@5-FU Nanostructures as Promising Nanocarriers: Physiochemical Characterization and Toxicity Activity

Today, cancer treatment is an important issue in the medical world due to the challenges and side effects of ongoing treatment procedures. Current methods can be replaced with targeted nano-drug delivery systems to overcome such side effects. In the present work, an intelligent nano-system consisting of Chitosan (Ch)/Gamma alumina (γAl)/Fe3O4 and 5-Fluorouracil (5-FU) was synthesized and designed for the first time in order to influence the Michigan Cancer Foundation-7 (MCF-7) cell line in the treatment of breast cancer. Physico-chemical characterization of the nanocarriers was carried out using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), vibrating sample magnetometry (VSM), dynamic light scattering (DLS), and scanning electron microscopy (SEM). SEM analysis revealed smooth and homogeneous spherical nanoparticles. The high stability of the nanoparticles and their narrow size distribution was confirmed by DLS. The results of the loading study demonstrated that these nano-systems cause controlled, stable, and pH-sensitive release in cancerous environments with an inactive targeting mechanism. Finally, the results of MTT and flow cytometry tests indicated that this nano-system increased the rate of apoptosis induction on cancerous masses and could be an effective alternative to current treatments.

Comment on "Old is Gold: Electrolyte Aging Influences the Topography, Chemistry, and Bioactivity of Anodized TiO2 Nanopores"

Self-organized anodic TiO₂ nanostructures, in the form of nanopores, nanotubes, mesosponge, etc., obtained by electrochemical anodization have in the past two decades attracted tremendous focus and the number of publications based on such structures for various applications is remarkable. Guo et al. in ACS Appl. Mater. Interfaces 2021, 13 (7), 7897-7912 discuss the obtaining of TiO₂ nanopores by anodization in an aged electrolyte and its influence on the nanopores' topography, chemistry, and bioactivity. Guo et al. do not include in their study sufficient SEM characterization to confirm the claimed nanopore morphology. This comment clarifies the difference between a nanotube and a nanopore structure, both by already existing literature and reproduced experimental results. In fact, anodization on similar substrates and in similar anodization conditions leads to a nanotube morphology covered at the top by an initiation layer, depending on the anodization duration and post-treatments, such as ultrasonication. It is noted that the type of nanostructure has a clear influence on the available inner surface area for porosity computation or biomedical applications, for example, targeting drug delivery and interactions with proteins. Here, a clearer classification into nanopores and nanotubes─with an open top or an initiation layer─is established and explained.

Engineered titania nanomaterials in advanced clinical applications

Significant advancement in the field of nanotechnology has raised the possibility of applying potent engineered biocompatible nanomaterials within biological systems for theranostic purposes. Titanium dioxide (titanium(IV) oxide/titania/TiO2) has garnered considerable attention as one of the most extensively studied metal oxides in clinical applications. Owing to the unique properties of titania, such as photocatalytic activity, excellent biocompatibility, corrosion resistance, and low toxicity, titania nanomaterials have revolutionized therapeutic approaches. Additionally, titania provides an exceptional choice for developing innovative medical devices and the integration of functional moieties that can modulate the biological responses. Thus, the current review aims to present a comprehensive and up-to-date overview of TiO2-based nanotherapeutics and the corresponding future challenges.

Anodic TiO2 Nanotubes: Tailoring Osteoinduction via Drug Delivery

TiO₂ nanostructures and more specifically nanotubes have gained significant attention in biomedical applications, due to their controlled nanoscale topography in the sub-100 nm range, high surface area, chemical resistance, and biocompatibility. Here we review the crucial aspects related to morphology and properties of TiO₂ nanotubes obtained by electrochemical anodization of titanium for the biomedical field. Following the discussion of TiO₂ nanotopographical characterization, the advantages of anodic TiO₂ nanotubes will be introduced, such as their high surface area controlled by the morphological parameters (diameter and length), which provides better adsorption/linkage of bioactive molecules. We further discuss the key interactions with bone-related cells including osteoblast and stem cells in in vitro cell culture conditions, thus evaluating the cell response on various nanotubular structures. In addition, the synergistic effects of electrical stimulation on cells for enhancing bone formation combining with the nanoscale environmental cues from nanotopography will be further discussed. The present review also overviews the current state of drug delivery applications using TiO₂ nanotubes for increased osseointegration and discusses the advantages, drawbacks, and prospects of drug delivery applications via these anodic TiO₂ nanotubes.

Evolution of anodised titanium for implant applications

Anodised titanium has a long history as a coating structure for implants due to its bioactive and ossified surface, which promotes rapid bone integration. In response to the growing literature on anodised titanium, this article is the first to revisit the evolution of anodised titanium as an implant coating. The review reports the process and mechanisms for the engineering of distinctive anodised titanium structures, the significant factors influencing the mechanisms of its formation, bioactivity, as well as recent pre- and post-surface treatments proposed to improve the performance of anodised titanium. The review then broadens the discussion to include future functional trends of anodised titanium, ranging from the provision of higher surface energy interactions in the design of biocomposite coatings (template stencil interface for mechanical interlock) to techniques for measuring the bone-to-implant contact (BIC), each with their own challenges. Overall, this paper provides up-to-date information on the impacts of the structure and function of anodised titanium as an implant coating in vitro and in/ex vivo tests, as well as the four key future challenges that are important for its clinical translations, namely (i) techniques to enhance the mechanical stability and (ii) testing techniques to measure the mechanical stability of anodised titanium, (iii) real-time/in-situ detection methods for surface reactions, and (iv) cost-effectiveness for anodised titanium and its safety as a bone implant coating.

Synthesis and characterization of chitosan/polyvinylpyrrolidone coated nanoporous γ-Alumina as a pH-sensitive carrier for controlled release of quercetin

pH-sensitive drug delivery systems based on amphiphilic copolymers constitute a promising strategy to overcome some challenges to cancer treatment. In the present study, quercetin-loaded chitosan/polyvinylpyrrolidone/γ-Alumina nanocomposite was fabricated through a double oil in water emulsification method for the first time. γ-Alumina was incorporated to improve the drug loading efficiency and release behavior of polyvinylpyrrolidone and chitosan copolymeric hydrogel. γ-Alumina nanoparticles were obtained by the sol-gel method with a nanoporous structure, high surface area, and hydroxyl-rich surface. Quercetin, a natural anticancer agent, was loaded into the nanocomposite as a drug model. XRD and FTIR analyses confirmed the crystalline properties and chemical bonding of the prepared nanocomposite. The size of drug-loaded nanocomposites was 141 nm with monodisperse particle distribution, having a spherical shape approved by DLS analysis and FE-SEM, respectively. Incorporating γ-Alumina nanoparticles improved the encapsulation efficiency up to 95%. Besides, swelling study and the quercetin release profile demonstrated that γ-Alumina ameliorated pH sensitivity of nanocomposite and a targeted controlled release was obtained. Various release kinetic models were applied to the experimental release data to study the mechanism of drug release. Through MTT assay and flow cytometry, the quercetin-loaded nanocomposite showed significant cytotoxicity on MCF-7 breast cancer cells. Also, the enhanced apoptotic cell death confirmed the anticancer activity of γ-Alumina. These results suggest that the chitosan/polyvinylpyrrolidone/γ-Alumina nanocomposite is a novel pH-sensitive drug delivery system for anticancer applications.

The Impacts of Crystalline Structure and Different Surface Functional Groups on Drug Release and the Osseointegration Process of Nanostructured TiO2

In implantable materials, surface topography and chemistry are the most important in the effective osseointegration and interaction with drug molecules. Therefore, structural and surface modifications of nanostructured titanium dioxide (TiO2) layers are reported in the present work. In particular, the modification of annealed TiO2 samples with -OH groups and silane derivatives, confirmed by X-ray photoelectron spectroscopy, is shown. Moreover, the ibuprofen release process was studied regarding the desorption-desorption-diffusion (DDD) kinetic model. The results proved that the most significant impact on the release profile is annealing, and further surface modifications did not change its kinetics. Additionally, the cell adhesion and proliferation were examined based on the MTS test and immunofluorescent staining. The obtained data showed that the proposed changes in the surface chemistry enhance the samples' hydrophilicity. Moreover, improvements in the adhesion and proliferation of the MG-63 cells were observed.

Old is Gold: Electrolyte Aging Influences the Topography, Chemistry, and Bioactivity of Anodized TiO2 Nanopores

Titanium dioxide (TiO₂) nanostructures including nanopores and nanotubes have been fabricated on titanium (Ti)-based orthopedic/dental implants via electrochemical anodization (EA) to enable local drug release and enhanced bioactivity. EA using organic electrolytes such as ethylene glycol often requires aging (repeated anodization of nontarget Ti) to fabricate stable well-ordered nanotopographies. However, limited information is available with respect to its influence on topography, chemistry, mechanical stability, and bioactivity of the fabricated structures. In the current study, titania nanopores (TNPs) using a similar voltage/time were fabricated using different ages of electrolyte (fresh/0 h to 30 h aged). Current density vs time plots of EA, changes in the electrolyte (pH, conductivity, and Ti/F ion concentration), and topographical, chemical, and mechanical characteristics of the fabricated TNPs were compared. EA using 10-20 h electrolytes resulted in stable TNPs with uniform size and improved alignment (parallel to the underlying substrate microroughness). Additionally, to evaluate bioactivity, primary human gingival fibroblasts (hGFs) were cultured onto various TNPs in vitro. The findings confirmed that the proliferation and morphology of hGFs were enhanced on 10-20 h aged electrolyte anodized TNPs. This pioneering study systematically investigates the optimization of anodization electrolyte toward fabricating nanoporous implants with desirable characteristics.

Preparation of pH-sensitive chitosan/polyvinylpyrrolidone/α-Fe2O3 nanocomposite for drug delivery application: Emphasis on ameliorating restrictions

Chitosan (CS)/polyvinylpyrrolidone (PVP)/hematite (α-Fe₂O₃) nanocomposites loaded with Doxorubicin (drug model) were synthesized via an oil-in-water emulsification method to develop a biocompatible and pH-sensitive drug nanocarrier for the first time. A hydrogel, including CS, PVP, and α-Fe₂O₃, was fabricated successfully with glutaraldehyde (GA) as the cross-linker. Incorporating α-Fe₂O₃ into CS/PVP hydrogel improved the pH-sensitivity and developed beneficial hydrogel. FTIR and XRD analysis illustrated physical interactions between polymer-polymer, polymer-drug, and crystalline behavior of prepared nanocomposite. These analyses also confirmed chemical bonding in nanocomposite's structure. The FE-SEM analysis showed successful impregnation of α-Fe₂O₃ into CS/PVP matrix and spherical structure. To clarify the size distribution and surface charge of the drug-loaded nanocomposite (CS/PVP/α-Fe₂O₃/Dox), DLS and zeta analyses were conducted. They showed the mean size of nanocomposites at about 247 nm. Drug-loaded CS/PVP/α-Fe₂O₃ nanocomposite and CS/PVP/Dox were studied for their release behavior and kinetics. Furthermore, the effect of α-Fe₂O₃ on release from CS/PVP/α-Fe₂O₃/Dox nanocomposite was investigated. That showed an increase in encapsulation of Doxorubicin and beneficial release behavior such as slow-release and retention effect. The release from this drug-loaded nanocomposite revealed excellent pH-sensitive and controlled release of the drug. Besides, the in vitro cytotoxicity and cell apoptosis were studied to recognize biological properties. These analyses revealed that drug-loaded nanocomposite caused high inhibition to MCF-7 cells in presence of α-Fe₂O₃ and proved the hematite's anti-cancer effect. By and large, this study confirmed CS/PVP/α-Fe₂O₃ nanocomposites as a potential candidate for the controlled pH-sensitive release of the drug.

Nanointeraction: The profound influence of nanostructured and nano-drug delivery biomedical implant surfaces on cell behavior

Nanostructured surfaces feature promising biological properties on biomaterials attracting large interest at basic research, implant industry development, and bioengineering applications. Thou, nanoscale interactions at a molecular and cellular level are not yet completely understood and its biological and clinical implications need to be further elucidated. As follows, the aim of this comprehensive review was to evaluate nanostructured surfaces at biomedical implants focusing on surface development, nanostructuration, and nanoengineered drug delivery systems that can induce specific cell interactions in all relevant aspects of biological, reparative, anti-bacterial, anti-inflammatory and clinical processes. The methods and the physio-chemical properties involved in nanotopography performance, the main cellular characteristics involved at surface/cell interaction, and a summary of results and outlooks reported in studies applying nanostructured surfaces and nano-drug delivery systems is presented. The future prospects and commercial translation of this developing field, particularly concerning multifunctional nanostructured surfaces and its clinical implications are further discussed. At a cellular level, nanostructured biomedical implant surfaces can enhance osteogenesis by targeting osteoblasts, osteocytes, and mesenchymal cells, stimulate fibroblast/epithelial cells proliferation and adherence, inhibit bacterial cell proliferation and biofilm accumulation, and act as immune-modulating surfaces targeting macrophages and reducing pro-inflammatory cytokine expression. Moreover, several methodological options to create drug-delivery systems on metallic implant surfaces are available, however, the clinical translation is yet incomplete. The efficiency of which nanostructured/nano-delivery surfaces may target specific cell interactions and favor clinical outcomes needs to be further elucidated in pre-clinical and clinical studies, along with engineering solutions for commercial translation and approval of controlling agencies.

Surface Heterogeneous Nucleation-Mediated Release of Beta-Carotene from Porous Silicon

We demonstrate that the release of a poorly soluble molecule from nanoporous carriers is a complex process that undergoes heterogeneous surface nucleation events even under significantly diluted release conditions, and that those events heavily affect the dynamics of release. Using beta-carotene and porous silicon as loaded molecule and carrier model, respectively, we show that the cargo easily nucleates at the pore surface during the release, forming micro- to macroscopic solid particles at the pores surface. These particles dissolve at a much slower pace, compared to the rate of dissolution of pure beta-carotene in the same solvent, and they negatively affect the reproducibility of the release experiments, possibly because their solubility depends on their size distribution. We propose to exploit this aspect to use release kinetics as a better alternative to the induction time method, and to thereby detect heterogenous nucleation during release experiments. In fact, release dynamics provide much higher sensitivity and reproducibility as they average over the entire sample surface instead of depending on statistical analysis over a small area to find clusters.

Long acting anti-infection constructs on titanium

Peri-prosthetic joint infections (PJI) are a serious adverse event following joint replacement surgeries; antibiotics are usually added to bone cement to prevent infection offset. For uncemented prosthesis, alternative antimicrobial approaches are necessary in order to prevent PJI; however, despite elution of drug from the surface of the device being shown one of the most promising approach, no effective antimicrobial eluting uncemented device is currently available on the market. Consequently, there is a clinical need for non-antibiotic antimicrobial uncemented prosthesis as these devices present numerous benefits, particularly for young patients, over cemented artificial joints. Moreover, non-antibiotic approaches are driven by the need to address the growing threat posed by antibiotic resistance. We developed a multilayers functional coating on titanium surfaces releasing chlorhexidine, a well-known antimicrobial agent used in mouthwash products and antiseptic creams, embedding the drug between alginate and poly-beta-amino-esters. Chlorhexidine release was sustained for almost 2 months and the material efficacy and safety was proven both in vitro and in vivo. The coatings did not negatively impact osteoblast and fibroblast cells growth and were capable of reducing bacterial load and accelerating wound healing in an excisional wound model. As PJI can develop weeks and months after the initial surgery, these materials could provide a viable solution to prevent infections after arthroplasty in uncemented prosthetic devices and, simultaneously, help the fight against antibiotic resistance.

Quercetin in the form of a nano-antioxidant (QTiO2) provides stabilization of quercetin and maximizes its antioxidant capacity in the mouse fibroblast model

Living cells are constantly exposed to reactive oxygen species (ROS) causing them to rely on a constant supply of exogenous antioxidants. Quercetin (Q) is one of the potent exogenous antioxidants utilized in various antioxidant formulations. However, the potential application of Q is largely limited because of its poor water solubility. In this study, we employed titanium dioxide (TiO₂) nanoparticles to maximize cellular penetration and antioxidant effect of Q on mouse fibroblast cells. To accomplish this, polyethylene glycol (PEG) modified TiO₂-nanoparticle surfaces were utilized that exhibited better dispersion, with enhanced biocompatibility. Cell viability assays using Q and Q-conjugated TiO₂-nanoparticles (QTiO₂) were evaluated in terms of cell morphology as well as with an immunoblotting analysis to look for key biomarkers of apoptosis. In addition, cleavages of Cas 3 and PARP were obtained in cells treated with Q. Furthermore, antioxidant defence with QTiO₂ was validated by means of the Nrf2 upregulation pathway. We also observed increased expressions of target enzymes; HO-1, NQO1 and SOD1 in QTiO₂-treated cells. The antioxidant potency of the QTiO₂ nano-antioxidant form was successfully tested in ROS and superoxide radicals induced cells. Our results demonstrated that the QTiO₂ nano-antioxidant promoted a high quercetin bioavailability and stability, in cells with maximal antioxidant potency against ROS, with no signs of cytotoxicity.

Monodisperse Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/PPy Core-Shell Composite Nanospheres for IBU Loading and Release

The magnetic targeting drug delivery system is an effective way of targeting therapy. In this study, the monodisperse Fe₃O₄ nanoparticles with a particles size of about 180 nm were first prepared via a solvothermal method. Subsequently, the core-shell structure Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/polypyrrole (PPy) composite nanospheres were successfully synthesized by coating Fe₃O₄ nanoparticles with SiO₂ shell layer using the Stöber method and PPy shell by solvothermal method in turn. The as-prepared nanoparticles were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR), vibrating sample magnetometer (VSM), thermogravimetric analysis (TGA), and Ultraviolet-Visible spectrophotometer (UV-Vis). The results indicated that the as-prepared composite nanospheres displayed a well-defined core-shell structure and monodispersity. The thicknesses of SiO₂ shell and PPy shell were ~6 nm and ~19 nm, respectively. Additionally, the as-prepared nanoparticles exhibited high saturation magnetization of 104 emu/g, 77 emu/g, and 24 emu/g, and have great potential applications in drug delivery. The drug loading and drug release of the Fe₃O₄/SiO₂ and Fe₃O₄/SiO₂/PPy composite nanospheres to ibuprofen (IBU) under stirring and ultrasonication were investigated. Their drug loading efficiency and drug release efficiency under ultrasonication were all higher than 33% and 90%, respectively. The drug release analyses showed sustained release of IBU from nanospheres and followed the Korsmeyer-Peppas model.

A Novel Methodology for Economical Scale-Up of TiO2 Nanotubes Fabricated on Ti and Ti Alloys

The prospective use of nanotechnology for medical devices is increasing. While the impact of material surface nanopatterning on the biological response is convincing, creating a large surface area with such nanotechnology remains an unmet challenge. In this paper, we describe, for the first time, a reproducible scale-up manufacturing technique for creating controlled nanotubes on the surfaces of Ti and Ti alloys. We describe an average of approximately 7.5-fold increase in cost and time efficiency with regards to the generation of 20, 50, and 100 nm diameter nanotubes using an anodisation technique. These novel materials have great potential in the medical field through their influence on cellular activity, in particular, protein absorption, focal adhesion, and osteoinduction. In this paper, we provide a step-by-step guide to optimise an anodisation system, starting with design rationale, proof of concept, device upscaling, consistency, and reproducibility check, followed by cost and efficiency analysis. We show that the optimised device can produce a high number of anodised specimens with customisable specimen shape at reduced cost and time, without compromising the repeatability and consistency. The device can fabricate highly uniform and vertically oriented TiO2 nanotube layer with desired pore diameters.

PLGA-amoxicillin-loaded layer formed on anodized Ti alloy as a hybrid material for dental implant applications

In this paper, the preparation of a functional hybrid coating loaded with a drug (amoxicillin) on a promising titanium alloy - Ti-15Mo alloy is presented. The titanium alloy surface was anodized in solution with bioactive compounds to obtain a porous oxide layer favorable for MG-63 osteoblast-like cell adhesion. Then, a poly(lactide-co-glycolide) (PLGA) loaded with amoxicillin layer was formed using a dip-coating technique to cover the oxide layer, without filling in all of the pores. The morphology of the surface was evaluated using scanning electron microscopy supported by 3D Roughness Reconstruction software. The surface treatment of the Ti-15Mo alloy surface caused the surface roughness to increase up to 1.71 μm. The anodization process caused the Ti-15Mo alloy surface to become slightly more hydrophilic; however, the formation of the PLGA layer loaded with drug increased the contact angle to 96.5° ± 2.2°, respectively. After 4 weeks of polymer layer degradation, the registered signals on the ¹H NMR spectrum were identical to the signals registered for lactic acid (LAc), which confirms that the polymer layer was degraded within a short period of time. The concentration of drug released into the artificial saliva was investigated using high-performance liquid chromatography (HPLC) up to 12 h of coatings immersion. During the first hour of coating degradation in artificial saliva, and the concentration of the drug (13 μg/ml) was enough to inhibit bacterial growth of S. aureus and S. epidermidis. These results were confirmed by agar plate diffusion method and evaluation of the minimal inhibitory concentration (MIC). The cytocompatibility of the materials was determined using the osteoblast-like cells MG-63, and the viability and cell morphology (live/dead staining) were also evaluated. The results showed that amoxicillin influences the osteoblast-like MG-63 cells' behavior during cell culture, especially for the first few hours. The influence on the type of surface treatment on MG-63 cell behavior during 7 days of culture is discussed in this paper. To the best of our knowledge, this is the first time that a fast-degrading layer with amoxicillin has been deposited on previously anodized Ti surface. The formation of functional coating may find application as a cytocompatible coating to prevent bacterial adhesion on long-term implant surfaces.

Surface modification of nanoporous anodic titanium dioxide layers for drug delivery systems and enhanced SAOS-2 cell response

Nowadays, titanium and its alloys are the most commonly used implantable materials. The surface topography and chemistry of titanium-based implants are responsible for osseointegration. One of the methods to improve biocompatibility of Ti implants is a modification with sodium hydroxide (NaOH) or 3-aminopropyltriethoxysilane (APTES). In the present study, anodic titanium dioxide (ATO) layers were electrochemically fabricated, and then immersed in a NaOH solution or in NaOH and APTES solutions. The functionalized samples were characterized by using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). All samples were examined as drug delivery systems and scaffolds for cell culturing. Based on the parameters of the fitted desorption-desorption-diffusion (DDD) model parameters, it was concluded that the modification with NaOH increased the amount of released ibuprofen and inhibited the release process. Osteoblast-like cell line (SAOS-2) was used to investigate the cell response on the non-modified and modified ATO samples. The MTS test and immunofluorescent staining were carried out to examine cell adhesion and proliferation. The data showed that the modification of nanoporous TiO₂ layers with small molecules such as APTES enhanced metabolic activity of adhered cells compared with the non-modified and NaOH-modified TiO₂ layers. In addition, the cells had a polygonal-like morphology with distinct projecting actin filaments and were well dispersed over the whole analyzed surface.

Tailoring the immuno-responsiveness of anodized nano-engineered titanium implants

Owing to its biocompatibility and corrosion resistance, titanium is one of the most commonly used implantable biomaterials. Numerous in vitro and in vivo investigations have established that titanium surfaces with a nanoscale topography outperform conventional smooth or micro-rough surfaces in terms of achieving desirable bonding with bone (i.e. enhanced bioactivity). Among these nanoscale topographical modifications, ordered nanostructures fabricated via electrochemical anodization, especially titania nanotubes (TNTs), are particularly attractive. This is due to their ability to augment bioactivity, deliver drugs and the potential for easy/cost-effective translation into the current implant market. However, the potential of TNT-modified implants to modulate the host immune-inflammatory response, which is critical for achieving timely osseointegration, remains relatively unexplored. Such immunomodulatory effects may be achieved by modifying the physical and chemical properties of the TNTs. Furthermore, therapeutic/bioactive enhancements performed on these nano-engineered implants (such as antibacterial or osteogenic functions) are likely to illicit an immune response which needs to be appropriately controlled. The lack of sufficient in-depth studies with respect to immune cell responses to TNTs has created research gaps that must be addressed in order to facilitate the design of the next generation of immuno-modulatory titanium implants. This review article focuses on the chemical, topographical and mechanical features of TNT-modified implants that can be manipulated in order to achieve immuno-modulation, as well as providing an insight into how modulating the immune response can augment implant performance.

Redox-active nanomaterials for nanomedicine applications

Nanomedicine utilizes the remarkable properties of nanomaterials for the diagnosis, treatment, and prevention of disease. Many of these nanomaterials have been shown to have robust antioxidative properties, potentially functioning as strong scavengers of reactive oxygen species. Conversely, several nanomaterials have also been shown to promote the generation of reactive oxygen species, which may precipitate the onset of oxidative stress, a state that is thought to contribute to the development of a variety of adverse conditions. As such, the impacts of nanomaterials on biological entities are often associated with and influenced by their specific redox properties. In this review, we overview several classes of nanomaterials that have been or projected to be used across a wide range of biomedical applications, with discussion focusing on their unique redox properties. Nanomaterials examined include iron, cerium, and titanium metal oxide nanoparticles, gold, silver, and selenium nanoparticles, and various nanoscale carbon allotropes such as graphene, carbon nanotubes, fullerenes, and their derivatives/variations. Principal topics of discussion include the chemical mechanisms by which the nanomaterials directly interact with biological entities and the biological cascades that are thus indirectly impacted. Selected case studies highlighting the redox properties of nanomaterials and how they affect biological responses are used to exemplify the biologically-relevant redox mechanisms for each of the described nanomaterials.

Ibuprofen nanocrystals developed by 22 factorial design experiment: A new approach for poorly water-soluble drugs

The reduction of the particle size of drugs of pharmaceutical interest down to the nano-sized range has dramatically changed their physicochemical properties. The greatest disadvantage of nanocrystals is their inherent instability, due to the risk of crystal growth. Thus, the selection of an appropriate stabilizer is crucial to obtain long-term physicochemically stable nanocrystals. High pressure homogenization has enormous advantages, including the possibility of scaling up, lack of organic solvents and the production of small particles diameter with low polydispersity index. The sequential use of high shear homogenization followed by high pressure homogenization, can modulate nanoparticles’ size for different administration routes. The present study focuses on the optimization of the production process of two formulations composed of different surfactants produced by High Shear Homogenization followed by hot High Pressure Homogenization. To build up the surface response charts, a 2² full factorial design experiment, based on 2 independent variables, was used to develop optimized formulations. The effects of the production process on the mean particle size and polydispersity index were evaluated. The best ibuprofen nanocrystal formulations were obtained using 0.20% Tween 80 and 1.20% PVP K30 (F1) and 0.20% Tween 80 and 1.20% Span 80 (F2). The estimation of the long-term stability of the aqueous suspensions of ibuprofen nanocrystals was studied using the LUMISizer. The calculated instability index suggests that F1 was more stable when stored at 4 °C and 22 °C, whereas F2 was shown to be more stable when freshly prepared.