Having friendly faces inside and outside the labs has always been a great motivator for me and is deeply appreciated. The size of the spheres was independent of Tg or composition and the overall average diameter of the 16 compositions was 95.6 μm. Characterization of the glass and microspheres shows that there is potential for all Gd and Ho samples to be used in the body for cancer hyperthermia.
B IOMATERIALS FROM G LASS
Radiation, as in chemotherapy, destroys both cancerous and healthy cells, so delivering the dose directly to the affected area increases treatment efficacy.9 90Y spheres are used for liver cancer, and their short half-life of 64 hours makes them a choice safe. 9-11 Radiotherapy works because x-rays damage cells' DNA, stopping all protein function and causing death.12 These. 90Y glass spheres are different from bioactive glass because they are not absorbed by the body.
H YPERTHERMAL C ANCER T REATMENT
This difference is essential to keep in mind when using hyperthermia treatment, as treatment duration must be adjusted based on cell type to ensure enough cancer cells are killed. Increasing body temperature causes a short-term dilation of blood vessels, an increase in the permeability of the vessel wall and an increase in blood flow.19 These physical effects result in an increase in the transport of nutrients through the body. The short-term effect of the temperature increase is good for tumors, but long-term heat has the opposite effect.
H ISTORY OF H YPERTHERMIA T REATMENT
Progressing into the 90s, many more studies were conducted on the effectiveness of hyperthermia in combination with radiotherapy. Looking at patients with glioblastoma, an aggressive brain cancer, an increase from 15% to 31% in 2-year survival was found in radiotherapy alone versus in combination with hyperthermia, respectively.27 Progress throughout the 1990s led to more definitive success than at first. day. Successes are also marked more in the possibility of survival through a short period of time than in complete remission of the cancer and total recovery of the patient.
M AGNETIC H YPERTHERMIA
An example of a typical loop with magnetic field (H) and magnetization (M) can be seen in Figure 2. There are many useful parameters that can be deduced from the hysteresis loop that relate to the saturation limits of the magnetic field and the field, respectively, is the magnetization that remains after when the field is reduced to zero, and is the magnetic field required to return the magnetization back to zero. In Neel relaxation, the particle has a fixed location and the direction of the magnetic moment rotates with the field, but in Brownian relaxation, the direction of the magnetic moment is fixed relative to the particle and the particle moves relative to the field. 35 Figure 3 shows the differences in magnetic field and superspin direction between Neel and Brownian relaxation.
M AGNETIC R ESONANCE I MAGING
MRIs work by generating a magnetic field that aligns the dipoles of water in the body. The alternating magnetic field generates a spin in the nucleus of molecules which causes radio waves to be emitted. Controlling the frequency of the magnetic field will control the material temperature rise within the body.
G ADOLINIUM
These radio waves are detected and analyzed allowing the differentiation of different types of tissues in the body.40 MRI is a well-established technique for identifying tumors, and it may also be just the tool needed to rule them out. While Gd is currently used in the medical world, it is not without side effects. The main concern in using Gd in the body is for long term kidney problems.
H OLMIUM
This chelation prevents ionic Gd from entering the body fluids and organs, but failure of this binding mechanism can occur which can lead to Gd contamination within the body.
I RON AND M ANGANESE
O BJECTIVE
The most important factor that will determine success is the iron release of the glasses.
EXPERIMENTAL PROCEDURE
M ATERIAL S YNTHESIS
- Glass Powder Synthesis
- Glass Microsphere Synthesis ......................................................... Error! Bookmark not defined
- X-Ray Diffraction (XRD)
- Thermal Analysis
- X-Ray Photoelectron Spectroscopy (XPS)
- Advanced Surface Area and Porosity (ASAP)
- Glass Particle Solubility and Ion Release
The glass particles were formed into glass microspheres by introducing the particles into a propane/oxygen flame, where they melted and formed a spherical liquid droplet by surface tension. The flame from the Hellcat burner (Carlisle Machine Works NJ, USA) is directed into a stainless steel container which collects the glass microspheres as they are ejected from the flame. The inner candle of the flame is clearly kept to 4 cm for each glass composition.
A combined differential thermal analyzer, thermal gravimetric analyzer and differential scanning calorimeter (DTA-TGA-DSC) (Stanton Redcroft STA 1640, Rheometric Scientific, Epsom, UK) was used to measure the glass transition temperature (Tg) of the powder. A heating rate of 20oC min-1 was used using an alumina crucible where an empty matching alumina crucible was used as a reference. To determine the surface area of the glass powder, Advanced Surface Area and Porosimetry, Micromeritics ASAP 2020 (Micrometrics Instrument Corporation, Norcross, USA) was performed.
Approximately 8 g of each powder was analyzed and the specific surface area was calculated using the Brunauer-Emmett-Teller (BET) method. For the Gd samples, all time periods were run, while the Ho, Fe, and Mn samples were recorded only in the 1000-h time period. The ion release profile of each glass was measured using inductively coupled plasma – optical emission spectroscopy (ICP – OES) on a Perkin-Elmer Optima 8000 (Perkin Elmer, MA, USA).
ICP - OES calibration standards for Si, Ge, Gd, Ho, Fe and Mn ions were prepared from a stock solution on a gravimetric basis.
G LASS M ICROSPHERE C HARACTERIZATION
Optical Microscopy
Corrosion Study
Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDX)
RESULTS AND DISCUSSION
G LASS P OWDER C HARACTERIZATION
Based on the XRD data it is clear that the samples range from glass-ceramic to glass. The glass transition temperature (Tg) was found by locating the first change in concavity above 400 ⵒC in the heat flow curve. Based on the heating rate of 20 ᵒC/min, Tg does not have a high degree of accuracy, as such the values are only reasonably accurate to ± 5 ᵒC.
Gd has been found to be a lattice former in glass systems 64-67 but can also act as a modifier. 68 , 69 The role of Gd is system dependent and can therefore be classified as an intermediate network. It was found that Mn is the former.75,76 On the basis of the thermal data it is not possible to make a definitive conclusion about the role of the elements in the glass lattice. Based on the lowering of Tg, the addition of the substituent appears to have a flow effect on the glass.
Lower glass transition temperatures result in easier microsphere formation, so based on thermal analysis, 15 Gd, 20 Ho, 20 Fe, and 20 Mn should have the best efficiency and lowest required temperature of flame to create spheres. However, using this explanation is contradictory to the decrease of NBO with increasing Gd concentration, and completely ignores the changing effect of Fe and Mn on NBO content. Gd has been found to decrease, then increase NBO levels in a borate glass system, which corroborates the data obtained here.68 Given this, the largest conclusion that can be drawn is that the concentration of the substituent has only a moderate effect. in the total structure of the system.
Future analysis of the effect that the complex network has on the binding energy of oxygen in any glass system will provide a better understanding of the level of NBO in that glass.
G LASS C ORROSION S TUDIES
Glass Particle Solubility and Ion Release
Although there was a high yield of microspheres in most assemblies, some were less successful than others. There was also a problem with small particles of glass frit sticking to the surfaces of the spheres. Most spheres are consistent in SE imaging, so surface texture is indicative of a local change in composition.
This corrosion was also found in 20 Gd and 15 Ho samples, but not in any of the lower mol% substituent spheres. A roughness, as seen in Figure 24, was developed on the surface of some of the balls. While corrosion of the balls occurs in a predictable manner, it occurs at a slow rate.
However, EDX analysis also showed the incorporation of Al in most samples. EDX element maps of the spheres before and after 1000 hours in the pH 7 environment are shown in Figure 27. The main conclusion drawn from these maps is that the spherization process does not have a major effect on the randomness of the glass network.
Since controlled consistency throughout the sphere is critical for medical applications, this is a promising result for sphere viability under hyperthermic treatment. Figure 29 shows a scaffold structure, where the pores take over the entire structure of the microsphere. A case similar to the pocket defect was found in which part of the globe became convex.
SUMMARY AND CONCLUSIONS
FUTURE WORK
Bagshaw, “Two or six hyperthermia treatments in addition to radiation therapy produce comparable tumor responses: results from a randomized trial,” Int. Amichetti, “Report of long-term follow-up in a randomized trial comparing radiotherapy and radiotherapy plus hyperthermia to metastatic lymph nodes in stage IV head and neck patients.” Sherar, “Radiotherapy with or without hyperthermia in the treatment of superficial localized breast cancer: results of five randomized controlled trials,” Int.
34;Survival Benefit of Hyperthermia in a Prospective Randomized Trial of Brachytherapy Boost ± Hyperthermia for Glioblastoma Multiforme," Int. Ivkov, "Magnetic Nanoparticle Hyperthermia Enhances Radiation Therapy: A Study in Mouse Models of Human Prostate Cancer," Int. "Magneticis, " Magneticis Hyperthermia therapy for the treatment of glioblastoma: A review of the therapy's history, efficacy, and use in humans,” Int.
34; FDA Drug Safety Communication: New Warnings for the Use of Gadolinium-Based Contrast Agents in Patients with Renal Dysfunction Accessed on: April 34; Manganese-porphyrin-enhanced MRI for cancer cell detection: a quantitative in vitro investigation with multiple clinical subtypes of breast cancer,” PLoS ONE. Osanai, “Evaluation of neuronal manganese uptake for activity-induced manganese-enhanced MRI,” Electron.
Wren, "Investigation of the Effect of Silver Coating on the Solubility, Antibacterial Properties, and Cytocompatibility of Glass Microspheres," J.
