The use of biogenic nanoparticles as targeted drug delivery systems has gained increasing attention for improving anticancer therapies. This study investigates the effectiveness of porous biosilica derived from the diatom Chaetoceros sp., functionalized with hydrophilic GPTMS, labeled with CD-19 antibody, and loaded with doxorubicin in targeting Raji cells, a B lymphoid cell line. Biosilica was extracted, purified, and modified for enhanced drug delivery. Characterization involved X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, zeta potential measurement, dynamic light scattering (DLS), Transmission Electron Microscopy (TEM), scanning electron microscopy (SEM), and Fourier-transform infrared (FT-IR) spectroscopy, followed by drug loading and release measurements. Cytotoxicity was assessed using the MTT assay and apoptosis tests, with Jurkat cells as non-target controls. Results confirmed successful GPTMS surface modification and revealed the amorphous structure of biosilica, with mean intraparticle pore sizes of 130 nm (BET). The drug loading capacity reached 53.92%. The system exhibited significant cytotoxic effects on Raji cells (IC = 0.1 mg/mL), with lower Jurkat cell survival (p < 0.05). Enhanced apoptosis was detected in Raji cells. These findings suggest the modified biosilica has substantial potential for targeted drug delivery, with the antibody enhancing attachment and release at target sites. Further investigation is needed to address biocompatibility and bioaccumulation for in vivo applications.