Cloning, biosensors, tissue engineering, fake organs, and regenerative medicine are all areas where biomedical technology is very important to modern medicine. But for most biological uses, we need complicated bio-functional materials like hydrogel, porous silicon nanoparticles, and 3D graphene frameworks. These materials need to be made in a very specific way so that we can control their qualities exactly as we want. These materials are often used in living things, so their biocompatibility, biodegradability, and possible harmful effects need to be carefully studied before they can be sold to the public. To make these high-performance biological uses more widely available at low cost and with few health risks, it is important to look into new materials that are easier to make.
Due to their amazing thermal, optical, and magnetic qualities, perovskite materials are quickly becoming more useful in biomedicine. The current state of research into perovskite-based biomedical uses is talked about in this chapter. These include using organic-inorganic hybrid perovskites for X-ray imaging and detection, as well as magnetic perovskite nanoparticles for controlling magnetism and temperature quickly and binding to bovine serum albumin. The hydroxyapatite–CaTiO3 composite’s biocompatibility and toxins are also talked about. In the last part, we will talk about the limits of biological perovskites and where future study should go.
Organic–Inorganic Hybrid Perovskites for X-Ray
Detection and Imaging
CH3NH3PbI3 (MAPbI3) Photodiode for Sensitive X-Ray
Detection
X-rays are very good at entering things, which makes them useful for medical procedures like CT scans, radiography, and radiotherapy that aim to diagnose and treat illnesses. Lead halide perovskites have been used to make X-ray photodetectors because they have a lot of electron-rich elements, a lot of charge carriers that can move around, and long carrier diffusion lengths. Yakunin et al. created a MAPbI3-based solar cell that works with the p–i–n junction’s built-in electrical potential when light causes carriers to be generated. When the sensor was exposed to synthetic one-sun AM1.5 light, it worked, which means it converted power 10.4% efficiently. We tested the photodiode with a MAPbI3 active layer against a reference silicon diode/YAG:Ce photodetector and found that it had more sensitive photocurrents. The average photocurrent from the MAPbI3 photodiode went up in a straight line with the dose rate of X-ray light. The sensitivity went up as the thickness went up. In MAPbI3, X-ray photons are absorbed more deeply and more efficiently than visible light. This is because the absorption coefficient l is very low in the 102–105 eV range for X-rays.
MAPbI3 Photoconductor for X-Ray Imaging with High
Responsivity
A study created a lateral photoconductor based on MAPbI3 that can change X-ray photons into X-rays with a peak energy of 75 keV. The photoconductor had great responsivity (R, >1.0 AW−1) for visible light from 550 to 750 nm, which was very close to the wavelength at which it naturally absorbs light, which is around 780 nm. After 10 ps of laser excitation, a time-domain photoluminescence peak with a full width at half maximum (FWHM) of 350 ps was seen, which shows a quick optical reaction. An active area of 0.0057 cm2 and an electric field of 10.0 kV/cm were used to make the photoconductor work. It had a MAPbI3 thickness of 60 lm and an electrode gap of about 100 lm. The photocurrent was close to 60 nA. Because it was so responsive, a plant leaf, a Kinder Surprise egg, and an electronic key card could all be imaged with high clarity using X-rays. The research shows that a photoconductor built on MAPbI3 could be useful for converting X-rays and measuring electron charge, photoconductive gain, and photon energy.
CH3NH3PbBr3 (MAPbBr3) Single Crystal for Low-Dose
X-Ray Imaging with High Sensitivity
Wei et al. made a MAPbBr3 single crystal that is 2 mm thick and can grow on a brominated triethoxysilane-modified silicon substrate. It has a –NH3–Br– atomic link at the interface, which lets X-ray imaging work very well with very little dose. Putting fullerene (C60) and bathocuproine (BCP) layers on top of MAPbBr3 made electron transport layers, which they then used to put together a working photodetector. The perovskite interface layer bound with –NH3–Br– had a long carrier lifetime of 692 ns, which shows that the silane molecules did not create any remaining charge quench states that would have hurt the carrier properties of MAPbBr3. It was 2 mm thick and had a sensitivity of 322 lC Gyair−1 cm−2 at -1 V bias and 50 keV X-ray energy, which meant it could identify a lower dose rate of 0.036 lGyairs−1. A linear pixel detector grid was made by making microstructures out of C60, BCP, and gold. We scanned an N-shaped object made of copper tubes in one direction and got high-quality X-ray photos at an extremely low dose rate of 247 nGyairs−1. This gave us a dose–area product (DAP) of 2.5 Gyair cm2 h−1 for a 20-cm-thick human testing area.
Polycrystalline MAPbI3 Photoconductor
with Polymer–Perovskite Interlayers
for Large-Area and Low-Dose X-Ray Imaging
It was done by Wei et al. who used a bulk MAPbBr3 single-crystal absorber to make X-ray images and forecast a promisingly low DAP on the human body. However, their use is still limited by the small detection area (5.8 mm x 5.8 mm surface area of MAPbBr3 crystal). To show X-ray imaging on big flat screens, it’s also necessary for materials to be able to be processed on thin-film transistor (TFT) array matrices. These are needed to send an electronic signal to tiny detectors so that images can be made.
Kim and his colleagues first put down thick layers of a mixed perovskite material on a hydrogen-doped amorphous silicon TFT array. This made a big active area that was 25.088 cm x 28.672 cm. They created a new type of photodetector with a MAPbI3 polycrystalline layer (MPC) that is hundreds of micrometres thick and is connected to polyimide-MAPbI3 (PIMAPbI3) and polyimide-MAPbBr3 (PIMAPbBr3) interlayers that are placed between charge collection electrodes. Large perovskite crystallites with sharp edges and clear crystalline planes were found in the device. This showed that the perovskite layers had high crystallinities and good charge transport qualities, which are needed for optical uses like X-ray photodetection.
Kim and his colleagues studied photoluminescence and optical absorption on MPC and spin-coated MAPbI3 (adduct MAPbI3) films to find out more about the optical and electronic features of a thick MPC layer. It is clear that the MPC film has a longer absorption start and photoluminescence peak wavelength than its adduct MAPbI3 cousin. This means that it has a smaller optical band gap and a lot more crystallinity than MAPbI3 that is normally synthesised. Time-resolved photoluminescence breakdown showed that the carrier lifetime was much longer on the MPC film compared to the hybrid MAPbI3 equivalent. This shows that the outstanding photonic qualities are good for future device use.
Kim and his colleagues wanted to find out more about the characteristics of the MPC-based X-ray detector they made, so they compared the mass attenuation coefficients of MAPbI3 to those of amorphous selenium (a-Se) [45, 59] and cadmium zinc telluride (Cd0.9Zn0.1Te) [60]. They discovered that MAPbI3 is much better at blocking X-rays than a-Se in the 30–200 keV energy range. This is because it absorbs high-Z I and Pb atoms at around 33 and 88 keV, respectively.
The amazing X-ray absorption power of MAPbI3 was measured by its X-ray absorption spectrum when tungsten radiation was excited at a high voltage of 100 kV and a 3-mm aluminium screen blocked the radiation. This 830-lm MPC-based detector showed a fast rise and fall in photocurrent when exposed to X-rays with pulse sizes of 50 ms and a dose rate of 1 mGyairs1. Since the main goal of an X-ray detector is to make medical images, photocurrents were studied at the pixelated detector. The current magnitude (measured in e mGyair−1 pixel−1) and device sensitivity steadily increased with positive bias voltage, which was due to better charge extraction.
Magnetic Perovskite Nanoparticles for In Vitro
Applications
La0.7Sr0.3Mn0.98Ti0.02O3 Perovskite Nanoparticles
with Magneto-Temperature Properties
Transition metal oxide perovskites are magnetic and have been used in many different ways, such as in ferroelectrics, ferromagnets, multiferroics, and topological insulators. In a study by J. Gong and T. Xu Soleymani et al., mixed-cation perovskite oxide (La0.7Sr0.3Mn0.98Ti0.02O3) nanoparticles were made by reacting Nic-A, an amorphous precursor, with Nic-B, a solid precursor. At 700°C, the amorphous precursor was heated to make solid La0.7Sr0.3Mn0.98Ti0.02O3, which has different crystalographic directions. Transmission electron microscopy (TEM) pictures showed that the nanoparticles had a shape that was characterised by their size, which was 23.5 nm on average. The Scherrer equation was used to figure out that the perovskite nanoparticles were 20.1 nm in size on average. The as-yet-synthesized nanoparticles showed a dynamic rise in temperature, hitting a cutoff temperature when heat production equalled heat loss. This sensitive rise in temperature when magnetic fields are applied from the outside, along with a stable cutoff temperature, shows that perovskite La0.7Sr0.3Mn0.98Ti0.02O3 has a lot of promise as a heating agent for cancer treatment based on high temperatures. The study shows that perovskite oxide perovskites might be useful as heating agents for cancer treatment based on high temperatures.
Perovskite La2NiMnO6 Nanoparticles for Adsorption
of Bovine Serum Albumin (BSA)
Manganite perovskites, like Ca-doped BiMnO3 and LaMnO3, are magnetic and could be used in many ways, like as sensors, to clean up the environment, to deliver drugs, for magnetic resonance imaging, immunoassays, and sorbents. Wu et al. made double-perovskite La2NiMnO6 by sintering it at high temperatures and letting the metal ions settle together. We confirmed that the nanoparticles had solid structures by looking at X-ray diffraction patterns and that they were round by looking at high-resolution TEM pictures. No matter what temperature was used, the La2NiMnO6 nanoparticles got to an average size of 37 nm. The adsorption studies of BSA protein by Wu and colleagues were based on ultraviolet spectra at 280 nm. They found that all of the nanoparticle samples had amazing BSA protein-adsorption abilities. La2NiMnO6 nanoparticles heated to 850 °C were able to absorb 200 mg/g of BSA in two sets of experiments. This shows that they are a good way to remove BSA and could have big effects in medical uses like cancer cell targeting probes and biosensors.
In Vitro Biocompatibility of (Ca10(PO4)6(OH)2–CaTiO3)
Composites in Cellular Cultures
CaTiO3 is a perovskite mineral that has been shown to help the growth of hydroxyapatite (HA), which is the main building block of bones, by acting as a support. CaTiO3 helps the body’s osseointegration and osteoblast binding to biomaterials that have been inserted. It has many electronic and mechanical qualities, including the ability to carry electricity, prevent rust, be ferroelectric, have high bonding strength, and be stable. In biological fields like biosensors, orthopaedics, and craniofacial repair, this makes it useful.
Dubey et al. did in vitro cell growth studies to show that SaOS2 human osteoblast cells and L929 mouse fibroblast cells can grow well on pure HA (H1C0), 60 wt% HA–40 wt% CaTiO3 composites, and 20 wt% HA–80 wt% CaTiO3 composites. The study found that thick bridge-like cytoplasmic links were made between cells. The cells strongly attached to the composite surfaces through flattened structures and extended filopodia, showing that the synthesised HA–CaTiO3 composites were biocompatible.
The 3(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that the number of metabolically active SaOS2 and L929 cells increased after being incubated on HA–CaTiO3 composites. This suggests that the cytotoxicity of HA–CaTiO3 composites did not have any negative effects on cell viability or at most, had very little effect on the cells that were studied.
Concluding Remarks
This chapter gives an overview of the success made in using perovskites in biological settings, focussing on their unique ability to be easily dissolved and shaped, as well as their good optical band gaps and high-Z Pb/I/Br heavy elements. MAPbX3 perovskites have been used to successfully identify and image X-rays, but the perovskite emitters need to be made more stable before these technologies can be used widely. When you switch to Cs+-cationed or MA+/Cs+ alloyed motifs, the band gaps get wider, which stops dark currents and makes perovskite materials much more stable structurally. Two-dimensional (2D) lead halide perovskites allow crystals to be arranged out of plane on the surfaces below, which could allow X-ray-induced photocarriers to move in very specific directions. In the future, scientists should focus on making thick, large-area 2D perovskite emitters on thin-film transistor arrays using printing and self-assembly methods that work well together.
The exact material phases of La0.7Sr0.3Mn0.98Ti0.02O3 perovskite nanoparticles have not been clearly explained because the relative amounts of metal cations are not known. No research has been done on how well La2NiMnO6 nanoparticles can remove BSA protein molecules. In the future, scientists should try to figure out how their structure and properties change in more complex chemical conditions where temperature, pH, and pressure can change.
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