S-TECH: sample preparation technology for point-of-care diagnostics
S-TECH is DNAiTECH's separation technology developed for sample preparation for point-of-care applications (POC). S-TECH is an innovative hands-free technology that is POC deployable without additional laboratory equipment.
Using DNAiTECH's S-TECH, it is simple to:
isolate subcellular particles,
extract nucleic acids,
purify and concentrate samples,
buffer exchange for PCR, ELISA, EM, PAGE, etc,
process volumes from 0.1-20 ml (depending on sample complexity),
recover the sample in 50-200 µl,
process samples on bench or on ice,
process large volumes of environmental samples.
S-TECH uses low-binding hydrophilic membranes for size exclusion. S-TECH is a gentle method relying on the vacuum for sample processing. S-TECH has a small footprint and is a cost-effective alternative to SEC columns, spin columns and ultracentrifugation. S-TECH membranes come in filtration cutoff sizes of 5000nm, 1000nm, 450nm, 200nm, 100nm, 50nm and 20nm. The S-20 is certified for virus capture down to 20nm. Our S-TECH A and B filters are for nucleic acid extractions. The figures below show the S-TECH device unit (right) and the setup for use (left). Vacuum is applied using a luer-lock syringe and a vac-lock device. The sample is loaded directly into the unit's well or with an attached 15ml reservoir.
The S-Tech Kit
Each S-TECH kit consists of the following components:
S-TECH units x 32 (user decides on membrane pore sizes).
S-TECH bases x 4.
S-TECH reservoirs x 4.
S-TECH vac-lock combs (1 ml, 10ml, 20ml, 30ml).
S-TECH as a point-of-care sample extraction technology.
S-TECH enables sample processing without centrifuges, columns and fraction collectors. This integrated process enables sample/particle purification, concentration, and buffer exchange in a single unit. Users can select different filter sizes for fractionating a sample. For instance, cells may be removed using large pore sizes (S-TECH 450-5000nm), micro-vesicles may be captured using S-TECH 200-1000nm and subcellular particles such as liposomes, exosomes and viruses may be captured using S-TECH 100-20nm. Nucleic acids may be captured using the S-TECH A and S-TECH B filters. When using the S-Tech devices, the fraction captured on the membrane is termed the retentate, and that which passes through the membrane into the syringe is the elute.
Example A: Urinary subcellular particle isolation
A urine sample (3 ml) was processed by removing cells on the S-450. The S-450 elute fraction was reprocessed using the S-100. The washed S-100 retentate was recovered in 200 µl of PBS. The S-100 elute fraction was processed through the S-20. Tunable resistive pulse sensing (Izon Science) was used to analyze the S-20 and the
S-100 retentate fractions.
Example A demonstrates the versatility of S-TECH to isolate sample particles from dilute biological samples, a single device for POC particle capture, washing and concentration in preparation for diagnostic tests.
Particle size distributions captured in S-20 (red) and S-100 (black) retentate fractions.
Example B: Plasma vesicle isolation
Bovine plasma was processed using S-20. The retentate was washed twice with PBS and analyzed by PAGE. The same sample was processed by SEC (Izon qEV) and ultracentrifugation for comparison purposes. The processed samples were compared by PAGE. Left the molecular markers, input sample, S-20 washed retentate, ultracentrifugation pellet, SEC fractions 7-9. The reduction of predominant albumin fractions was evident in all three methods. The particle numbers per 100µg protein recovered by S-TECH were higher than by SEC and ultracentrifugation.
The particle numbers recovered per 100 µg of protein.
9.40E+08 particles/100 µg
6.75E+08 particles/100 µg
S-20 Washed Retentate
4.94 E+09 particles/100 µg
Example C: Nucleic acid extraction using S-TECH A and S-TECH B
POC diagnostics require sample preparation without lab equipment, which eliminates the use of centrifuges and spin columns which are common requirements in other commercial methods for nucleic acid extraction. Our extraction method uses two types of membrane for extraction after cell disruption using chaotropic agents. S-TECH membrane A removes remaining particulates after extraction. The elute from S-TECH A is then processed onto S-TECH membrane B for nucleic acid capture. The DNA is eluted from S-TECH B in 50-200 µl TE or water.
Soil is a challenging sample for molecular diagnostics because of potential humic acid inhibition. We demonstrated the versatility of our method, extracting soil samples with and without E. coli, elution of the DNA from S-TECH B and amplification of DNA using Looped-mediated amplification (LAMP). The extracts were completely non-inhibitory for LAMP reactions.
E. coli LAMP
Soil - E. coli
Soil + E. coli