1. MATERIAL CHARACTERIZATION
Material characterization is the crucial first step in the biological evaluation process. The extend of chemical characterization depends on what pre-clinical and clinical safety and toxicological data exist, and on the nature and duration of body contact with the medical device, but as a minimum the characterization shall address the constituent chemicals of the device and constituent residual process aids or additives used in its manufacture.
The following material characterization facilities are available :
Fourier Transform Infrared (FTIR)
Turnaround time : 7 days
IR analysis would give a wavelength versus absorption spectrum and by matching the IR spectrum of an unknown material with that of a known material, proof of identity can be established within the limits of the method.
Normal scan range 400 cm-1 to 4000 cm-1
UV Visible spectroscopy
Turnaround time : 8 days
Most widely used technique for quantitative molecular analysis for the identification and structural analysis of organic compounds. It provides valuable information through the absorption spectrum which is unique for a given compound.
Approved protocol based on ASTM E 169-93
High Performance Liquid Chromatography (HPLC)
Turnaround time : 7 days
To separate and analyse complex mixtures or solutions which include liquids and solids of both organic and inorganic origins.
Approved protocol
Gel Permeation Chromatography (GPC)
Turnaround time : 10 days
GPC is often used to determine the relative molecular weight of polymer samples as well as the distribution of molecular weights.
Approved protocol based on ASTM S 5296-05
Thermal Analysis
Turnaround time : DSC/DTA/TGA - 6 days
Thermal Analysis includes DSC (Differential Scanning calorimetry), DTA (Differential thermal Analysis) and TGA(Thermo Gravimetric Analysis).
DSC measures the amount of heat absorbed or released by a sample as it is heated or cooled or kept at constant temperature(isothermal).
DTA- measures the temperature difference between a sample and a reference material as a function of temperature as they are heated or cooled or kept at a constant temperature (isothermal).DTA provides vital information of the materials regarding their endothermic and exothermic behaviour at high temperatures.
TGA- Determination of mass loss of materials. TGA is effective for quantitative analysis of thermal reactions that areaccompanied by mass changes, such as evaporation, decomposition, gas absorption,desorption and dehydration.
Temp range : DSC -50 °C to 400 °C; DTA - RT t o 1400 °C; TGA- RT to 1400°C
Glass transition temperature - AS TM- E 1 3 5 6 - 0 3
TGA - AS TM- E1131 - 03
Dynamic Mechanical Analysis
Turnaround time : 30 days
Dynamic Mechanical Analysis determines elastic modulus (or storage modulus, G'), viscous modulus (or loss modulus, G'') and damping coefficient (Tan delta) as a function of temperature, frequency or time. Results are typically provided as a graphical plot of G', G'', and Tan delta versus temperature. DMA identifies transition regions in plastics, such as the glass transition, and may be used for quality control or product development. DMA can recognize small transition regions that are beyond the resolution of DSC (Differential Scanning Calorimetry).Applicable to polymers and polymeric biomaterials. Not applicable for ceramics, metals or liquids
Facility to test at temperatures from -100°C to +300°C and frequency from 0.01 to 100Hz
Micro hardness testing
Turnaround time : 6 days
The test measures the Micro Hardness of solid materials such as metals, alloys, ceramics and polymers by microscopic indentation test method..
ASTM E 384-99
Mechanical Testing
Turnaround time : 15 days
Mechanical testing of polymers, composite materials, ceramics, bone, soft tissues and medical devices.
ISO 527 and equivalent
Impact Testing
Turnaround time : 15 days
Impact tests allow designers to compare the relative impact resistance under controlled laboratory conditions and, consequently, are often used for material selection or quality control.
Izod and Charpy impact testing available.
Applicable to plastics, ceramics, polymer composites and polymeric biomaterials
Not applicable for rubbers and liquids.
ASTM D6110 & D256; ISO 179 & 180.
Thermocycler
Turnaround time : 15 days
The Thermocycler with its cold and warm bath tank is used for simulation of thermal load cycles of composites.
Approved protocol
Profilometry
Turnaround time : 15 days
Measures line & surface profiles. Various roughness parameters are estimated for the line profile. Both surface roughness and waviness parameters are estimated for surface profile.
Approved protocol
Micro CT
Turnaround time : 15 days
Micro CT finds application in the 3D scanning of bone, ceramic, tooth, polymers , tissue engineered products etc.
Approved protocol
Scanning Electron Microscopy (SEM) & Energy dispersive x-ray analysis using SEM
Turnaround time : 30 days
Scanning electron microscopy has been applied to the surface studies of metals,ceramics, polymers, composites and biological materials for both topography as well ascompositional analysis.
Approved protocol
Transmission Electron Microscopy (TEM)
Turnaround time : 60 days
Transmission electron microscopy is used to study the local structures, morphology, and dispersion of multi-component polymers, cross sections & crystallization of metallic alloys and semiconductors, microstructure of composite materials, etc.
Approved protocol
2. BIOLOGICAL TESTS
In vitro Cytotoxicity
Turnaround time : 30 days
Preliminary screening test preceding animal tests and clinical studies.
Three methods are available: Direct contact method in which the test article is placed in direct contact with monolayer of cells; in agar diffusion method , semi solid agar is layered over cell monolayer and test article is placed on the agar layer and in test on extracts, a serially diluted extract of a material is used for cytotoxicity.L929 cells are used .
ISO 10993-5
Delayed hypersensitivity
Turnaround time : 90 days
Hypersensitivity tests shall be used to estimate the potential for contact sensitization by medical devices, materials and/or their extracts. These tests are important because exposure or contact to even minute amounts of potential leachables can result in allergic or sensitization reactions. The skin reactions are graded on a ranking scale according to the degree of erythema and edema. Two methods are generally used : closed patch method and maximization method. Guinea pigs are used for the test.
ISO 10993-10
Irritation
Turnaround time : Intracutaneous (dermal) reactivity test, Animal skin irritation - 90 days
vaginal irritation, penile irritation - 120 days
Irritation tests shall be used to estimate the irritation potential of medical devices, materials and/or their extracts, using an appropriate site for application such as skin, eye and mucous membrane. The intracutaneous reactivity test shall be used to assess the localized reaction of tissue to medical device extracts.This test is applicable where the determination of irritation by dermal or mucosal tests is inappropriate. Rabbits are used for the test.
Intracutaneous (dermal) reactivity test, Animal skin irritation, vaginal irritation, penile irritation - ISO 10993-10
Intracutaneous test - USP 31, NF 26
Acute systemic toxicity
Turnaround time : 90 days
Acute systemic toxicity tests shall be used where contact allows potential absorption of leachables and degradable products to estimate the potential harmful effects of either single or multiple exposures, during a period of less than 24 hours to medical devices, materials and/or their extracts. Mice are used for the test.
Acute intravenous & intraperitoneal application - ISO 10993-11
Systemic injection test - USP 31, NF 26
Implantation
Turnaround time : Short term - 150 days
Implantation tests shall be used to assess the local pathological effects on living tissue, at both the gross level and microscopic level, of a sample of a material or final product that is surgically implanted or placed in an implant site or tissue appropriate to the intended application. Rabbits are used for the test.
Implantation in muscle, bone and subcutaneous tissue - ISO 10993-6
Short term - 1 week, 4 weeks, 12 weeks
Log term - 12 weeks, 26 weeks, 52 weeks, 78 weeks
Genotoxicity
Turnaround time :
A battery of in vitro genotoxicity tests employing mammalian or non-mammalian cell culture or other techniques shall be used to determine gene mutaions, changes in chromosome structure and number, and other DNA and gene toxicities caused by medical devices, materials and/or their extracts. Both in vitro and in vivo tests are carried out. Mice are used for the in vivo tests.
• Mammalian bone marrow chromosomal aberration test
• Mammalian erythrocyte micronucleus test
• In vitro chromosomal aberration test in peripheral human blood lymphocyte
• In vitro bacterial reverse mutation assay(Ames test)
ISO 10993-3
Pyrogen Test
Turnaround time : 90 days
Pyrogenicity tests are included to detect material - mediated pyrogenic reactions of extracts of medical devices or materials.
ISO 10993-11
Hemolytic Property
Turnaround time : 90 days
Determine the degree of red blood cell lysis and the release of hemoglobin. Rabbit blood is used for the test.
ASTM F756
In vitro hemocompatibilitry
Turnaround time : 90 days
The purpose of hemocompatibility testing is to look for possible undesirable changes in the blood caused directly by a medical device or by chemicals leaching from a device. Undesirable effects of device materials on the blood may include hemolysis, thrombus formation, alterations in coagulation parameters, and immunological changes. Hemocompatibility tests fall in five different categories--thrombosis, coagulation, platelets, hematology, and immunology.
ISO 10993-4
Microbiological Sterility
Turnaround time : If sample has no antibacterial activity - 30 days
If sample has antibacterial activity - 55 days
Sterility test is done using pharmacopoeia methods to detect batches of pharmaceuticals / devices that should not be released into the market. Another application is in the validation and revalidation of sterilization process.
USP 71
Bioburden
Turnaround time : 30 days
Bioburden test is usually carried out to estimate the biobrden on devices which would help in determining the sterilization requirements of the device.
Approved protocol based on ISO 11737
Antimicrobial Testing
Turnaround time : 25 days
Assess the antimicrobial activity of a substance. Microbial strains used for the study are:
S.aureus and E.coli.
Gross & histopathological evaluation
Turnaround time : Soft tissue (60 days), hard tissue (90 days)
Gross & histopathological evaluation is carried out in tissue specimens (soft/hard) , immunohistochemistry staining are also carried out. Histopathological evaluation is carried out for post implantation samples of bone, subcutaneous tissue and muscle.
Implantation in muscle, bone and subcutaneous tissue - ISO 10993-6
Other tests offered includes