Sterilization Types And Methods Pdf
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The purpose of this Guidance Document for Disinfectants and Sterilization Methods is to assist lab personnel in their decisions involving the judicious selection and proper use of specific disinfectants and sterilization methods.
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Find more information on the Altmetric Attention Score and how the score is calculated. Bioprinting has emerged as a valuable three-dimensional 3D biomanufacturing method to fabricate complex hierarchical cell-containing constructs.
Spanning from basic research to clinical translation, sterile starting materials are crucial. In this study, we present pharmacopeia compendial sterilization methods for the commonly used bioink component alginate. Autoclaving sterilization in saturated steam and sterile filtration followed by lyophilization as well as the pharmacopeia noncompendial method, ultraviolet UV -irradiation for disinfection, were assessed. The impact of the sterilization methods and their effects on physicochemical and rheological properties, bioprinting outcome, and sterilization efficiency of alginate were detailed.
This set of methods provides a blueprint for the analysis of sterilization effects on the rheological and physicochemical pattern of bioink components and is easily adjustable for other polymers used in the field of biofabrication in the future. Figure 1. Figure 2. A Amplitude sweep from 0. B Frequency sweep from 0. C Shear stress sweep and D shear rate sweep from 0. Figure 3. Three-dimension 3D printed line patterns after different sterilization techniques compared to untreated alginate.
A—F represents a nine-line pattern and G—H a five-line pattern. Figure 4. Sterile sample left , sample containing B. Such files may be downloaded by article for research use if there is a public use license linked to the relevant article, that license may permit other uses.
More by Thomas Lorson. More by Matthias Ruopp. More by Ali Nadernezhad. More by Julia Eiber. More by Ulrich Vogel. More by Tomasz Jungst. Cite this: ACS Omega , 5 , 12 , — ACS AuthorChoice. Article Views Altmetric -. Citations 3. Abstract High Resolution Image. Biofabrication has emerged as a new and rapidly growing field 1 with applications in tissue engineering and regenerative medicine.
For successfully bridging the gap from research to applied clinical practice, reliable and effective sterilization of the applied polymers is critical during early-stage bioink development. Sterility of biomaterials and implants is mandatory, as sadly documented by implant-related infections related to increased patient morbidity and fatalities. However, due to the requirements of bioinks, sterilization processes for medical devices ISO norm or small molecules and pharmaceutical relevant polymers in solution pharmacopeial methods cannot be directly transferred.
One reason is the temperature stability, which is in general higher for metals used for load-bearing implants than for polymers as used in bioinks, causing degradation or chemical changes. Consequently, it is important to evaluate the suitability of the sterilization method in line with the physicochemical and mechanical properties of the sterilized material.
Although the number of publications dealing with biofabrication has been significantly increasing over the last few years, to the best of our knowledge, only one study investigated sterility and its influence on material properties. However, this method is not practicable in every laboratory due to its high safety requirements and high-cost involvement.
Here, we focus on pharmacopeia compendial, potentially high throughput, and cost-effective sterilization methods applicable in routine laboratory work. To this end, we selected sodium alginate as the bioink component, a commonly used bioink in 3D bioprinting, and compared the effects of the sterilization treatment on physicochemical and rheological properties, bioprinting, and sterilization efficiency.
Results and Discussion. Two compendial sterilization methods, autoclaving powder and liquid and sterile filtration, were compared for their sterilization outcome on the polysaccharide alginate Table 1.
For comparison, disinfection with ultraviolet UV -light was selected as the noncompendial method. Table 1. First, we analyzed the molar mass distribution of alginate by gel permeation chromatography GPC measurements in an aqueous environment after the sterilization or disinfection process Figure 1 A,B.
Compared to the nonsterilized alginate polymer, a low molecular tailing at larger retention volumes 5—7 mL was detected in the RI signal after the autoclaving process Figure 1 A. This finding was corroborated by differential pressure changes, which were lower for autoclaved samples Figure 2 B. Moreover, the resulting number average molar mass M n was statistically significantly lower by 17 and 19 kDa for autoclaved alginate as a powder or in an aqueous solution, respectively Figure 2 C.
The weight average molar mass M w was found to be statistically significantly lower after autoclaving alginate as an aqueous solution. High Resolution Image. To investigate if the observed changes in the molar mass distribution lead to macroscopic effects on printability, in-depth rheology studies were performed.
Oscillatory Figure 2 A,B , as well as rotatory measurements Figure 2 C,D , revealed a distinct impact on material properties. We hypothesize that the short-chain fragments that were generated during moist-heat treatment by autoclaving act as a plasticizer, resulting in a reduced chain entanglement of the polymer.
Consequently, both the stiffness as well as the energy stored during deformation were reduced, thereby at least in part influencing the printability of alginate. We assume that the breakdown of elastic components is related to significant degradation of the material during the sterilization process. Moreover, autoclaving caused the disappearance of an explicit yield point present in other samples at around 10 Pa Figure 2 C. Increasing the shear rate from 0.
This rheological behavior is typically observed for polymer solutions due to the increasing orientation of the polymer chains with an increasing shear rate. The viscosity decreased from 6. To this end, we used 3D printing experiments to analyze if the observed changes impact the rheology of the autoclaved alginate solutions and hence their printability Figure 3.
Therefore, line patterns were used as a default for the 3D printing process Figure 3 A,G. After printing, the autoclaved solutions, independent of whether autoclaved as powder or solution, revealed a loss of their shape fidelity Figure 3 E,F,K,L. In these autoclaved solutions, extrusion leads to wide viscous strands, which immediately merged into each other resulting in a fully filled construct. The shape-loss effect was more pronounced with alginate that was autoclaved as a powder Supporting Videos S4 , S5 , S9 , and S These findings are supported by the changes in the rheological behavior and reduced molecular weight Figures 1 C and 2 discussed previously.
In contrast, printed line structures for all other alginates native, UV-irradiated, and sterile-filtered samples were preserved and retained their shape. Native, UV-treated, and sterile-filtered alginate solutions were printable with accuracy tradeoffs at the points where the printer positioned the needle for the extrusion of new lines.
Moreover, all samples revealed a slight interlacing of the lines at the turning points of the given line structure. This finding may be attributed to the absence of CaCl 2 for stabilization of the 3D printed structure by alginate cross-linking. Sodium alginate, approved by the FDA 26 as a food-additive, is considered as noncytotoxic.
No significant differences between the differently sterilized alginates were observed, indicating good cell compatibility of all alginates after the sterilization process. Important to note is that only the influence of the material was investigated while bioprinting was not investigated.
In a final step, we evaluated the sterility of all samples discussed above according to the European Pharmacopeia. Beforehand, the inhibitory effects of all polymer samples were excluded by validation with various type of strains prescribed in the European Pharmacopeia.
Sterility testing revealed the existence of Bordetella bronchiseptica in the unsterilized starting material and in the UV-treated alginate sample Figure S1. In contrast, the sterile-filtered and subsequently lyophilized alginate sample remained sterile after 14 days of incubation in liquid media. These findings are of major importance as disinfection by UV-light is frequently used in the field of biofabrication. By analyzing pharmacopeia compendial methods for sterilization of the model bioink component alginate, we developed sterilization strategies suitable for sensitive polymers applied in biofabrication.
First, sterilization of a potential bioink should be investigated in the early phase of bioink development. Second, UV-light treatment as a noncompendial method was not effective in terms of sterilization outcomes and should be avoided. Based on the examined methods, we recommend sterile filtration at low polymer concentrations followed by lyophilization to obtain both sterile and printable bioinks. Materials and Methods.
UV-light sterilization of sodium alginate powder was performed under a TL universal UV lamp Camag, Muttenz, Switzerland at nm wavelength and a distance of 2 cm for 1 h. Specimen handling and filtration were conducted under a safety cabinet in a clean room. The system splits the sample into two parts for separate incubation in thioglycollate broth and soybean—casein digest medium. They were visually inspected for turbidity every working day.
In case of possible bacterial growth, 0. In the case of Schaedler agar, incubation took place in an anaerobic atmosphere. In the case of growth, colonies according to their morphology were isolated and subjected to Vitek mass spectrometry MS analysis for bacterial species assignment. In none of the strains, a negative impact of the product on microorganism recovery was observed.
Data were processed using RheoCompass software version 1. The flow rate was adjusted to 0. Prior to each measurement, the samples were filtered through a Whatman Puradisc 0. Data were processed using OmniSEC software version 5.
Other Sterilization Methods
Sterilization refers to any process that removes, kills, or deactivates all forms of life in particular referring to microorganisms such as fungi , bacteria , spores , unicellular eukaryotic organisms such as Plasmodium , etc. Sterilization is distinct from disinfection , sanitization, and pasteurization , in that those methods reduce rather than eliminate all forms of life and biological agents present. After sterilization, an object is referred to as being sterile or aseptic. One of the first steps toward modernized sterilization was made by Nicolas Appert who discovered that thorough application of heat over a suitable period slowed the decay of foods and various liquids, preserving them for safe consumption for a longer time than was typical. Canning of foods is an extension of the same principle and has helped to reduce food borne illness "food poisoning".
Other sterilization methods include filtration, ionizing radiation (gamma and electron-beam radiation), and gas. (ethylene oxide, formaldehyde). For products that.
Environmental Health & Safety
This acceptance comes at an especially critical time for the FDA to continue our important work to mitigate ethylene oxide sterilized device shortages. The FDA believes the Ethylene Oxide Sterilization Master File Pilot Program should result in sterilization facilities using a greatly reduced amount of ethylene oxide while still providing robust patient safeguards. The FDA will continue in its efforts to reduce over-reliance on ethylene oxide for medical device sterilization and will provide updates on future Master File acceptances. Medical devices are sterilized in a variety of ways including using moist heat steam , dry heat, radiation, ethylene oxide gas, vaporized hydrogen peroxide, and other sterilization methods for example, chlorine dioxide gas, vaporized peracetic acid, and nitrogen dioxide. Ethylene oxide sterilization is an important sterilization method that manufacturers widely use to keep medical devices safe.
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