The present invention provides nucleosides comprising a sterically hindered silyl protecting group on the exocyclic nitrogen atom of the nucleobase, oligonucleotides comprising the same, and methods for producing the same. Sub-carriers are divided into two sub-sets, where the sub-sets contain an equal number of sub-carriers. Thus, the macroalgae of the marine biomass resources is used so that a carbon source can be more easily extracted than that of a lignocellulosic biomass resource without a problem of having an effect on grain price like a crop-based biomass. The second spray-dried powder contains spray-dried particles formed from a pharmaceutically acceptable hydrophobic excipient but are substantially free of any therapeutically active ingredient.