The hydrothermal processing of iron oxides from bacterial biofilm waste as new nanomaterials for broad applications.

Iron oxides and their hydroxides have been studied and analysed with properties of their mutual transformations under different hydrothermal conditions being indicated. Amorphous bacteria nanowires produced from biofilm waste were investigated under the influence of pH at a fixed duration (20 h) and reaction temperature (200 °C). The morphology, structure, and particle size of the transformation of hematite (α-Fe2O3) was obtained and characterised with SEM, XRD, FTIR, and particle sizer. The optimal conditions for the complete conversion of amorphous iron oxide nanowires to crystalline α-Fe2O3 is under acidic conditions where the pH is 1. The flower-like α-Fe2O3 structures have photocatalytic activity and adsorbent properties for heavy metal ions. This one-pot synthesis approach to produce α-Fe2O3 at a low cost would be greatly applicable to the recycling process of biofilm waste in order to benefit the environment.

Multifunctional microspherical magnetic and pH responsive carriers for combination anticancer therapy engineered by droplet-based microfluidics.

pH stimuli responsive drug delivery platforms that can target specific locations along the gastrointestinal tract hold great promise for colorectal cancer therapy. Herein, we present a facile approach to produce microfluidic engineered pH-sensitive magnetic microspherical carriers containing multifunctional therapeutic payloads for synergistic treatment of colorectal cancer. Chemotherapeutics, 5 fluorouracil (5FU) and curcumin (CUR), were chosen due to their synergistic effect for colorectal cancer treatment and prevention. Drugs were loaded onto naturally derived porous silicon nanoparticles (SiNPs) and magnetic bacterial iron oxide nanowires (BacNWs), which acted as drug nanocontainers and magnetic elements, respectively. Drug loaded SiNPs and BacNWs were then encapsulated into polymeric microspheres using droplet-based microfluidics. To ensure controlled drug delivery into the desired site of action (colon and rectum), the microspheres were fabricated using hypromellose acetate succinate polymers, which are insoluble in the acidic medium of the stomach (i.e. pH 1.2) but soluble at basic pH (colon and rectum). Our results confirmed that the microspheres exhibit a narrow size distribution (CV > 5%) with precise size control. Moreover, in vitro dissolution and drug release data confirmed their pH-responsive properties. Motivated by these results, we explored the biocompatibility of microspheres using human RAW 264.7 macrophages. The results revealed the safety of drug free microspheres up to 1000 µg mL-1. Finally, the synergistic action of 5FU and CUR loaded microspheres was investigated on SW480 colon adenocarcinoma cells.

Naturally Derived Iron Oxide Nanowires from Bacteria for Magnetically Triggered Drug Release and Cancer Hyperthermia in 2D and 3D Culture Environments: Bacteria Biofilm to Potent Cancer Therapeutic.

Iron oxide nanowires produced by bacteria (Mariprofundus ferrooxydans) are demonstrated as new multifunctional drug carriers for triggered therapeutics release and cancer hyperthmia applications. Iron oxide nanowires are obtained from biofilm waste in the bore system used to pump saline groundwater into the River Murray, South Australia (Australia) and processed into individual nanowires with extensive magnetic properties. The drug carrier capabilities of these iron oxide nanowires (Bac-FeOxNWs) are assessed by loading anticancer drug (doxorubicin, Dox) followed by measuring its elution under sustained and triggered release conditions using alternating magnetic field (AMF). The cytotoxicity of Bac-FeOxNWs assessed in 2D (96 well plate) and 3D (Matrigel) cell cultures using MDA-MB231-TXSA human breast cancer cells and mouse RAW 264.7 macrophage cells shows that these Bac-FeOxNWs are biocompatible even at concentrations as high as 250 µg/mL after 24 h of incubation. Finally, we demonstrate the capabilities of Bac-FeOxNWs as potential hyperthermia agent in 3D culture setup. Application of AMF increased the local temperature by 14 °C resulting in approximately 34% decrease in cell viability. Our results demonstrate that these naturally produced nanowires in the form of biofilm can efficiently act as drug carriers with triggered payload release and magnetothermal heating features for potential anticancer therapeutics applications.

Iron Oxide Nanowires from Bacteria Biofilm as an Efficient Visible-Light Magnetic Photocatalyst.

Naturally produced iron oxide nanowires by Mariprofundus ferrooxydans bacteria as biofilm are evaluated for their structural, chemical, and photocatalytic performance under visible-light irradiation. The crystal phase structure of this unique natural material presents a 1-dimensional (1D) nanowire-like geometry, which is transformed from amorphous to crystalline (hematite) by thermal annealing at high temperature without changing their morphology. This study systematically assesses the effect of different annealing temperatures on the photocatalytic activity of iron oxide nanowires produced by Mariprofundus ferrooxydans bacteria. The nanowires processed at 800 °C were the most optimal for photocatalytic applications degrading a model dye (rhodamine B) in less than an hour. These nanowires displayed excellent reusability with no significant loss of activity even after 6 cycles. Kinetic studies by using hydrogen peroxide (radical generator) and isopropyl alcohol (radical scavenger) suggest that OH• is the dominant photooxidant. These nanowires are naturally produced, inexpensive, highly active, stable, and magnetic and have the potential to be used for broad applications including environmental remediation, water disinfection, and industrial catalysis.