The most notable achievement in the area of de novo long oligo synthesis in recent years is the development of the template-independent enzymatic oligo synthesis (TiEOS) technologies, primarily utilizing engineered terminal deoxynucleotidyl transferases (TdT). While these technologies hold great promise, they are not without shortcomings. For example, the large enzyme-to-nucleotide mass ratio is not atomically economic, which may be one of the reasons for the high cost of the methods if the enzyme is not used in catalytic quantities or recycled. The higher-order structures of long oligos may reduce synthesis efficiency. The coupling time may be lengthy, and the coupling yield may not meet the expectations for typical enzymatic reactions. In addition, enzymatic methods typically lack a capping step, increasing the likelihood of deletion errors. The TdT enzyme exhibits inherent nucleotide biases, leading to lower coupling efficiency for certain nucleotides, a problem that may be difficult to overcome through enzyme engineering. Finally, the method may be difficult to be adapted for synthesizing long oligos with site-specific modifications. In contrast to the resources invested in developing enzymatic methods for long oligo synthesis, little effort has been dedicated to advancing chemical methods over the past decade, even though many of the aforementioned shortcomings of enzymatic methods may be addressable using chemical approaches. Since 2010, our research team has been making efforts on the development of a new method called catching-by-polymerization (CBP) for synthetic oligo purification (Scheme 1). The method involves tagging the full-length oligo with a polymerizable tagging phosphoramidite (PTP) and incorporating the conjugate into a polyacrylamide gel. Because failure oligos are capped during automated synthesis, they are not tagged with the PTP, and therefore cannot be incorporated into the gel. Oligo purification is then achieved by washing away the failure oligos, followed by cleaving the full-length oligo from the gel. Recognizing the power of the CBP method, we attempted to use it to isolate the extremely low percentage of full-length oligos from the complex mixture generated from thousands of reactions required long oligo synthesis. Most recently, using the CBP method, we succeeded in isolation of 400-mers. Sanger sequencing confirmed the sequences. Here, with additional innovations involving the use of glass wool and glass beads as solid support for long oligo synthesis, we report the synthesis of the 800-mer green fluorescent protein (GFP) gene and the 1,728-mer Φ29 DNA polymerase gene, and their isolation with CBP and characterization with Sanger sequencing.