Higher Yields for Synthetic DNA Oligonucleotides

The biology revolution has created a large demand for high-quality oligonucleotides, resulting in many companies developing novel approaches to improve chemical DNA synthesis. Synthetic oligonucleotides are critical to modern techniques in nearly all disciplines of modern biology.  A growing use, and perhaps commercially the most feasible, form of DNA synthesis is the creation of primers and probes for PCR. PCR works by using a relatively short (around 100 nt) single stranded DNA template. The DNA double helix unwinds during replication, exposing unpaired bases for new nucleotides to hydrogen bond to.   Without the primer template PCR is unable to amplify DNA. Probes are also relatively short oligonucleotide sequences that are capped with a fluorophore and a quencher.  Their sequence rarely change in the ends, which generate a hairpin structure to keep the fluorophore from emitting unless the mid-section of the probe finds a complementary strand of DNA to bind.  In this case the hairpin is unfolded and the quencher and fluorophore separated by the exonuclease activity of DNA polymerase during amplification.  As a result the solution becomes fluorescent which indicates the presence of the sought DNA sequence. These two areas are two of the key roles for oligonucleotide DNA synthesis. 

Current techniques,  based on CMOS/Silicon chip phosphoramidite chemistry, give high quality but are limited in the length of sequences that can be generated and suffer from poor yields. Here, we provide an overview of the current state of the art techniques for synthetic DNA generation with an emphasis on the chemistry and process engineering involved. We also discuss advancements that promise to improve yield and generate longer sequences.   

Growing Billions of Human Cells in the Lab... Faster!

There are four fundamental types of tissues in the human body: epithelium tissue, which is responsible for absorbing or secreting materials and for protecting tissue surfaces; muscular tissue, which is responsible for the movements of body organs such as the digestive tract and for skeletal movement; connective tissue, the most widely distributed tissue in the body supports and connects other tissues together; and finally, nervous tissue, which is capable of receiving stimuli and transferring signal and then bringing about a response.

Biopharma's Worst Nightmare: An FDA Recall.

Part I: The Good

The year 2017 was full of positive news for the Biopharma industry. Several biologic therapeutic “firsts” have recently been approved by the FDA: Kymriah, the first gene therapy in the US, which is approved for the treatment of patients up to 25 years of age with B-cell precursor acute lymphoblastic leukemia that is refractory or in second or later relapse; MACI, the first FDA-approved product for repairing knee cartilage defects in adults that is grown from cells on scaffolds using healthy cartilage tissue from the patient’s own knee; Odactra, the first allergenic extract to be administered under the tongue for the treatment of house dust mite-induced nasal inflammation; and Haegarda, the first subcutaneous preventive treatment option for hereditary angioedema (HAE), which enables easier at-home self-injection by the patient or caregiver, to prevent HAE attacks in adolescent and adult patients. Dozens of other promising biologic therapeutics and treatments are in the pipeline. The race to profitable biologics is on!

Biopharma's Worst Nightmare: An FDA Recall.

Part II: The Bad


Biologics have revolutionized the treatment of such chronic illnesses as rheumatoid arthritis, psoriasis, psoriatic arthritis, Crohn's disease, and multiple sclerosis, and are widely used in treating a variety of cancers. To name just a few, these products include Enbrel, Humira, Remicade (infliximab), Avonex (inteferon beta-1a), Betaseron (interferon beta-1b), Tysabri, Cimzia (certolizumab pegol), Herceptin (trastuzumab), Rituxan (rituximab), Neupogen (filgrastim), Erythropoietin (EPO), Neulasta (pegfilgrastim) and Leukine (sargramostim). 

 A drug is typically manufactured through chemical synthesis, which means that it is made by combining specific chemical ingredients in an ordered process.

Biopharma's Worst Nightmare: An FDA Recall.

Part III: The Ugly

Detection is one way to avoid having a contaminated batch from being released. However, detection cannot eliminate bacteria as a potential contaminant. Burkholderia cepacia, a common cause of FDA recalls, could be eliminated, in principle, using micro-filtration, 0.2 - 0.4 micron filters. In practice, the pore size in micro filters are just an average value, not a guaranteed maximum pore size. Pore size distributions are statistical measures around a mean value. Smaller and larger pores are possible. The specified average pore size only assures the value of the average pore size, not the size of the largest available pore or the absence of pinhole imperfections in the manufactured of the industry standard cellulosic (paper) and nylon (polymeric) filters.  Note also that micro-filtration cannot eliminate mycoplasma, even if the stated pore size, say 0.2 microns, could be made within a very narrow distribution, say within a maximum deviation of 10% (0.18-0.22 microns). Scanning electron micrographs of most commonly used filters in bio-pharmaceutical production and R&D ...

Biopharma's Worst Nightmare: An FDA Recall.

Part IV: Gunfight at the OK Corral

Consider that a typical animal cell measures roughly 10 µm across. Bacterial cells are typically about 1 micron, 1000 nm, and viruses can be 10 times smaller than bacteria. Somewhere around 50 nm we can separate life threatening components from life sustaining ones. To illustrate this concept, we depict the typical size limits between life giving (biologics, nutrients, water) and life-threatening agents (viruses, bacteria, cancer cells). A clear demarcation, around 50-60 nanometers, exist between these two regimes, as illustrated in Fig. 4. We can think of this limit as a bio-safety GATEWAY that must be closely guarded to eliminate potential sources of contamination for both R&D practices as well as in biologics and pharmaceutical production streams….

The Age of Photonics: Beyond Electronics

Current electronics are prevalent in almost every aspect of day-to-day life. However, from fiber optics and telecommunications to medical imaging and cancer research, optics and photonics are advancing today’s critical technologies.


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